diff --git a/app/vmagent/README.md b/app/vmagent/README.md
index d398389fd..56b2c1ebe 100644
--- a/app/vmagent/README.md
+++ b/app/vmagent/README.md
@@ -24,8 +24,8 @@ additionally to [discovering Prometheus-compatible targets and scraping metrics
   see [these docs](https://docs.victoriametrics.com/#how-to-scrape-prometheus-exporters-such-as-node-exporter).
 * Can add, remove and modify labels (aka tags) via Prometheus relabeling. Can filter data before sending it to remote storage. See [these docs](#relabeling) for details.
 * Can accept data via all the ingestion protocols supported by VictoriaMetrics - see [these docs](#how-to-push-data-to-vmagent).
-* Can replicate collected metrics simultaneously to multiple remote storage systems -
-  see [these docs](#replication-and-high-availability).
+* Can aggregate incoming samples by time and by labels before sending them to remote storage - see [these docs](https://docs.victoriametrics.com/stream-aggregation.html).
+* Can replicate collected metrics simultaneously to multiple remote storage systems - see [these docs](#replication-and-high-availability).
 * Works smoothly in environments with unstable connections to remote storage. If the remote storage is unavailable, the collected metrics
   are buffered at `-remoteWrite.tmpDataPath`. The buffered metrics are sent to remote storage as soon as the connection
   to the remote storage is repaired. The maximum disk usage for the buffer can be limited with `-remoteWrite.maxDiskUsagePerURL`.
@@ -126,6 +126,12 @@ If you use Prometheus only for scraping metrics from various targets and forward
 then `vmagent` can replace Prometheus. Typically, `vmagent` requires lower amounts of RAM, CPU and network bandwidth compared with Prometheus.
 See [these docs](#how-to-collect-metrics-in-prometheus-format) for details.
 
+### Statsd alternative
+
+`vmagent` can be used as an alternative to [statsd](https://github.com/statsd/statsd)
+when [stream aggregation](https://docs.victoriametrics.com/stream-aggregation.html) is enabled.
+See [these docs](https://docs.victoriametrics.com/stream-aggregation.html#statsd-alternative) for details.
+
 ### Flexible metrics relay
 
 `vmagent` can accept metrics in [various popular data ingestion protocols](#how-to-push-data-to-vmagent), apply [relabeling](#relabeling)
diff --git a/app/vmagent/remotewrite/remotewrite.go b/app/vmagent/remotewrite/remotewrite.go
index d64d38113..5a67c4a34 100644
--- a/app/vmagent/remotewrite/remotewrite.go
+++ b/app/vmagent/remotewrite/remotewrite.go
@@ -21,6 +21,7 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/procutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promrelabel"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/streamaggr"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/tenantmetrics"
 	"github.com/VictoriaMetrics/metrics"
 	"github.com/cespare/xxhash/v2"
@@ -58,6 +59,13 @@ var (
 		"Excess series are logged and dropped. This can be useful for limiting series cardinality. See https://docs.victoriametrics.com/vmagent.html#cardinality-limiter")
 	maxDailySeries = flag.Int("remoteWrite.maxDailySeries", 0, "The maximum number of unique series vmagent can send to remote storage systems during the last 24 hours. "+
 		"Excess series are logged and dropped. This can be useful for limiting series churn rate. See https://docs.victoriametrics.com/vmagent.html#cardinality-limiter")
+
+	streamAggrConfig = flagutil.NewArrayString("remoteWrite.streamAggr.config", "Optional path to file with stream aggregation config. "+
+		"See https://docs.victoriametrics.com/stream-aggregation.html ."+
+		"See also -remoteWrite.streamAggr.keepInput")
+	streamAggrKeepInput = flagutil.NewArrayBool("remoteWrite.streamAggr.keepInput", "Whether to keep input samples after the aggregation with -remoteWrite.streamAggr.config ."+
+		"By default the input is dropped after the aggregation, so only the aggregate data is sent to the -remoteWrite.url. "+
+		"See https://docs.victoriametrics.com/stream-aggregation.html")
 )
 
 var (
@@ -140,6 +148,7 @@ func Init() {
 		logger.Fatalf("cannot load relabel configs: %s", err)
 	}
 	allRelabelConfigs.Store(rcs)
+
 	configSuccess.Set(1)
 	configTimestamp.Set(fasttime.UnixTimestamp())
 
@@ -435,9 +444,13 @@ var (
 )
 
 type remoteWriteCtx struct {
-	idx        int
-	fq         *persistentqueue.FastQueue
-	c          *client
+	idx int
+	fq  *persistentqueue.FastQueue
+	c   *client
+
+	sas                 *streamaggr.Aggregators
+	streamAggrKeepInput bool
+
 	pss        []*pendingSeries
 	pssNextIdx uint64
 
@@ -469,6 +482,7 @@ func newRemoteWriteCtx(argIdx int, at *auth.Token, remoteWriteURL *url.URL, maxI
 	}
 	c.init(argIdx, *queues, sanitizedURL)
 
+	// Initialize pss
 	sf := significantFigures.GetOptionalArgOrDefault(argIdx, 0)
 	rd := roundDigits.GetOptionalArgOrDefault(argIdx, 100)
 	pssLen := *queues
@@ -481,7 +495,8 @@ func newRemoteWriteCtx(argIdx int, at *auth.Token, remoteWriteURL *url.URL, maxI
 	for i := range pss {
 		pss[i] = newPendingSeries(fq.MustWriteBlock, sf, rd)
 	}
-	return &remoteWriteCtx{
+
+	rwctx := &remoteWriteCtx{
 		idx: argIdx,
 		fq:  fq,
 		c:   c,
@@ -490,6 +505,19 @@ func newRemoteWriteCtx(argIdx int, at *auth.Token, remoteWriteURL *url.URL, maxI
 		rowsPushedAfterRelabel: metrics.GetOrCreateCounter(fmt.Sprintf(`vmagent_remotewrite_rows_pushed_after_relabel_total{path=%q, url=%q}`, queuePath, sanitizedURL)),
 		rowsDroppedByRelabel:   metrics.GetOrCreateCounter(fmt.Sprintf(`vmagent_remotewrite_relabel_metrics_dropped_total{path=%q, url=%q}`, queuePath, sanitizedURL)),
 	}
+
+	// Initialize sas
+	sasFile := streamAggrConfig.GetOptionalArg(argIdx)
+	if sasFile != "" {
+		sas, err := streamaggr.LoadFromFile(sasFile, rwctx.pushInternal)
+		if err != nil {
+			logger.Fatalf("cannot initialize stream aggregators from -remoteWrite.streamAggrFile=%q: %s", sasFile, err)
+		}
+		rwctx.sas = sas
+		rwctx.streamAggrKeepInput = streamAggrKeepInput.GetOptionalArg(argIdx)
+	}
+
+	return rwctx
 }
 
 func (rwctx *remoteWriteCtx) MustStop() {
@@ -501,6 +529,8 @@ func (rwctx *remoteWriteCtx) MustStop() {
 	rwctx.fq.UnblockAllReaders()
 	rwctx.c.MustStop()
 	rwctx.c = nil
+	rwctx.sas.MustStop()
+	rwctx.sas = nil
 	rwctx.fq.MustClose()
 	rwctx.fq = nil
 
@@ -509,6 +539,7 @@ func (rwctx *remoteWriteCtx) MustStop() {
 }
 
 func (rwctx *remoteWriteCtx) Push(tss []prompbmarshal.TimeSeries) {
+	// Apply relabeling
 	var rctx *relabelCtx
 	var v *[]prompbmarshal.TimeSeries
 	rcs := allRelabelConfigs.Load().(*relabelConfigs)
@@ -526,11 +557,17 @@ func (rwctx *remoteWriteCtx) Push(tss []prompbmarshal.TimeSeries) {
 		rowsCountAfterRelabel := getRowsCount(tss)
 		rwctx.rowsDroppedByRelabel.Add(rowsCountBeforeRelabel - rowsCountAfterRelabel)
 	}
-	pss := rwctx.pss
-	idx := atomic.AddUint64(&rwctx.pssNextIdx, 1) % uint64(len(pss))
 	rowsCount := getRowsCount(tss)
 	rwctx.rowsPushedAfterRelabel.Add(rowsCount)
-	pss[idx].Push(tss)
+
+	// Apply stream aggregation if any
+	rwctx.sas.Push(tss)
+	if rwctx.sas == nil || rwctx.streamAggrKeepInput {
+		// Push samples to the remote storage
+		rwctx.pushInternal(tss)
+	}
+
+	// Return back relabeling contexts to the pool
 	if rctx != nil {
 		*v = prompbmarshal.ResetTimeSeries(tss)
 		tssRelabelPool.Put(v)
@@ -538,6 +575,12 @@ func (rwctx *remoteWriteCtx) Push(tss []prompbmarshal.TimeSeries) {
 	}
 }
 
+func (rwctx *remoteWriteCtx) pushInternal(tss []prompbmarshal.TimeSeries) {
+	pss := rwctx.pss
+	idx := atomic.AddUint64(&rwctx.pssNextIdx, 1) % uint64(len(pss))
+	pss[idx].Push(tss)
+}
+
 var tssRelabelPool = &sync.Pool{
 	New: func() interface{} {
 		a := []prompbmarshal.TimeSeries{}
diff --git a/app/vmalert/README.md b/app/vmalert/README.md
index 7ff7d747a..107529ad6 100644
--- a/app/vmalert/README.md
+++ b/app/vmalert/README.md
@@ -69,16 +69,17 @@ Then configure `vmalert` accordingly:
     -external.label=replica=a                # Multiple external labels may be set
 ```
 
-Note there's a separate `remoteWrite.url` to allow writing results of
+Note there's a separate `-remoteWrite.url` command-line flag to allow writing results of
 alerting/recording rules into a different storage than the initial data that's
 queried. This allows using `vmalert` to aggregate data from a short-term,
 high-frequency, high-cardinality storage into a long-term storage with
 decreased cardinality and a bigger interval between samples.
+See also [stream aggregation](https://docs.victoriametrics.com/stream-aggregation.html).
 
 See the full list of configuration flags in [configuration](#configuration) section.
 
 If you run multiple `vmalert` services for the same datastore or AlertManager - do not forget
-to specify different `external.label` flags in order to define which `vmalert` generated rules or alerts.
+to specify different `-external.label` command-line flags in order to define which `vmalert` generated rules or alerts.
 
 Configuration for [recording](https://prometheus.io/docs/prometheus/latest/configuration/recording_rules/)
 and [alerting](https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/) rules is very
@@ -514,8 +515,8 @@ groups:
       expr: avg_over_time(http_requests[5m])
 ```
 
-Ability of `vmalert` to be configured with different `datasource.url` and `remoteWrite.url` allows
-reading data from one data source and backfilling results to another. This helps to build a system
+Ability of `vmalert` to be configured with different `-datasource.url` and `-remoteWrite.url` command-line flags
+allows reading data from one data source and backfilling results to another. This helps to build a system
 for aggregating and downsampling the data.
 
 The following example shows how to build a topology where `vmalert` will process data from one cluster
@@ -539,7 +540,7 @@ Please note, [replay](#rules-backfilling) feature may be used for transforming h
 
 Flags `-remoteRead.url` and `-notifier.url` are omitted since we assume only recording rules are used.
 
-See also [downsampling docs](https://docs.victoriametrics.com/#downsampling).
+See also [stream aggregation](https://docs.victoriametrics.com/stream-aggregation.html) and [downsampling](https://docs.victoriametrics.com/#downsampling).
 
 #### Multiple remote writes
 
diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index 4be9c377e..80b8d0313 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -15,6 +15,7 @@ The following tip changes can be tested by building VictoriaMetrics components f
 
 ## tip
 
+* FEATURE: [vmagent](https://docs.victoriametrics.com/vmagent.html): add support for aggregation of incoming [samples](https://docs.victoriametrics.com/keyConcepts.html#raw-samples) by time and by labels. See [these docs](https://docs.victoriametrics.com/stream-aggregation.html) and [this feature request](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3460).
 * FEATURE: [vmui](https://docs.victoriametrics.com/#vmui): add ability to explore metrics exported by a particular `job` / `instance`. See [these docs](https://docs.victoriametrics.com/#metrics-explorer) and [this feature request](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3386).
 * FEATURE: allow passing partial `RFC3339` date/time to `time`, `start` and `end` query args at [querying APIs](https://docs.victoriametrics.com/#prometheus-querying-api-usage) and [export APIs](https://docs.victoriametrics.com/#how-to-export-time-series). For example, `2022` is equivalent to `2022-01-01T00:00:00Z`, while `2022-01-30T14` is equivalent to `2022-01-30T14:00:00Z`. See [these docs](https://docs.victoriametrics.com/#timestamp-formats).
 * FEATURE: [relabeling](https://docs.victoriametrics.com/vmagent.html#relabeling): add support for `keepequal` and `dropequal` relabeling actions, which are supported by Prometheus starting from [v2.41.0](https://github.com/prometheus/prometheus/releases/tag/v2.41.0). These relabeling actions are almost identical to `keep_if_equal` and `drop_if_equal` relabeling actions supported by VictoriaMetrics since `v1.38.0` - see [these docs](https://docs.victoriametrics.com/vmagent.html#relabeling-enhancements) - so it is recommended sticking to `keep_if_equal` and `drop_if_equal` actions instead of switching to `keepequal` and `dropequal`.
diff --git a/docs/README.md b/docs/README.md
index 280c0bf0b..56ea4e324 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -83,6 +83,7 @@ VictoriaMetrics has the following prominent features:
   * [Arbitrary CSV data](#how-to-import-csv-data).
   * [Native binary format](#how-to-import-data-in-native-format).
   * [DataDog agent or DogStatsD](#how-to-send-data-from-datadog-agent).
+* It supports powerful [stream aggregation](https://docs.victoriametrics.com/stream-aggregation.html), which can be used as a [statsd](https://github.com/statsd/statsd) alternative.
 * It supports metrics [relabeling](#relabeling).
 * It can deal with [high cardinality issues](https://docs.victoriametrics.com/FAQ.html#what-is-high-cardinality) and
   [high churn rate](https://docs.victoriametrics.com/FAQ.html#what-is-high-churn-rate) issues via [series limiter](#cardinality-limiter).
diff --git a/docs/Single-server-VictoriaMetrics.md b/docs/Single-server-VictoriaMetrics.md
index 7100424a0..4fe577056 100644
--- a/docs/Single-server-VictoriaMetrics.md
+++ b/docs/Single-server-VictoriaMetrics.md
@@ -86,6 +86,7 @@ VictoriaMetrics has the following prominent features:
   * [Arbitrary CSV data](#how-to-import-csv-data).
   * [Native binary format](#how-to-import-data-in-native-format).
   * [DataDog agent or DogStatsD](#how-to-send-data-from-datadog-agent).
+* It supports powerful [stream aggregation](https://docs.victoriametrics.com/stream-aggregation.html), which can be used as a [statsd](https://github.com/statsd/statsd) alternative.
 * It supports metrics [relabeling](#relabeling).
 * It can deal with [high cardinality issues](https://docs.victoriametrics.com/FAQ.html#what-is-high-cardinality) and
   [high churn rate](https://docs.victoriametrics.com/FAQ.html#what-is-high-churn-rate) issues via [series limiter](#cardinality-limiter).
diff --git a/docs/stream-aggregation.md b/docs/stream-aggregation.md
new file mode 100644
index 000000000..50234ae8d
--- /dev/null
+++ b/docs/stream-aggregation.md
@@ -0,0 +1,438 @@
+---
+sort: 98
+---
+
+# streaming aggregation
+
+[vmagent](https://docs.victoriametrics.com/vmagent.html) and [single-node VictoriaMetrics](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html)
+can aggregate incoming [samples](https://docs.victoriametrics.com/keyConcepts.html#raw-samples) in streaming mode by time and by labels.
+The aggregation is applied to all the metrics received via any [supported data ingestion protocol](https://docs.victoriametrics.com/#how-to-import-time-series-data)
+and/or scraped from [Prometheus-compatible targets](https://docs.victoriametrics.com/#how-to-scrape-prometheus-exporters-such-as-node-exporter).
+
+The stream aggregation is configured via the following command-line flags:
+
+- `-remoteWrite.streamAggr.config` at [vmagent](https://docs.victoriametrics.com/vmagent.html).
+  This flag can be specified individually per each specified `-remoteWrite.url`.
+  This allows writing different aggregates to different remote storage destinations.
+- `-streamAggr.config` at [single-node VictoriaMetrics](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html).
+
+These flags must point to a file containing [stream aggregation config](#stream-aggregation-config).
+
+By default only the aggregated data is written to the storage. If the original incoming samples must be written to the storage too,
+then the following command-line flags must be specified:
+
+- `-remoteWrite.streamAggr.keepInput` at [vmagent](https://docs.victoriametrics.com/vmagent.html).
+  This flag can be specified individually per each specified `-remoteWrite.url`.
+  This allows writing both raw and aggregate data to different remote storage destinations.
+- `-streamAggr.keepInput` at [single-node VictoriaMetrics](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html).
+
+Stream aggregation ignores timestamps associated with the input [samples](https://docs.victoriametrics.com/keyConcepts.html#raw-samples).
+It expects that the ingested samples have timestamps close to the current time.
+
+## Use cases
+
+Stream aggregation can be used in the following cases:
+
+* [Statsd alternative](#statsd-alternative)
+* [Recording rules alternative](#recording-rules-alternative)
+* [Reducing the number of stored samples](#reducing-the-number-of-stored-samples)
+* [Reducing the number of stored series](#reducing-the-number-of-stored-series)
+
+### Statsd alternative
+
+Stream aggregation can be used as [statsd](https://github.com/statsd/statsd) altnernative in the following cases:
+
+* [Counting input samples](#counting-input-samples)
+* [Summing input metrics](#summing-input-metrics)
+* [Quantiles over input metrics](#quantiles-over-input-metrics)
+* [Histograms over input metrics](#histograms-over-input-metrics)
+
+### Recording rules alternative
+
+Sometimes [alerting queries](https://docs.victoriametrics.com/vmalert.html#alerting-rules) may require non-trivial amounts of CPU, RAM,
+disk IO and network bandwith at metrics storage side. For example, if `http_request_duration_seconds` histogram is generated by thousands
+of app instances, then the alerting query `histogram_quantile(0.99, sum(increase(http_request_duration_seconds_bucket[5m])) without (instance)) > 0.5`
+can become slow, since it needs to scan too big number of unique [time series](https://docs.victoriametrics.com/keyConcepts.html#time-series)
+with `http_request_duration_seconds_bucket` name. This alerting query can be sped up by pre-calculating
+the `sum(increase(http_request_duration_seconds_bucket[5m])) without (instance)` via [recording rule](https://docs.victoriametrics.com/vmalert.html#recording-rules).
+But this recording rule may take too much time to execute too. In this case the slow recording rule can be substituted
+with the following [stream aggregation config](#stream-aggregation-config):
+
+```yaml
+- match: 'http_request_duration_seconds_bucket'
+  interval: 5m
+  without: [instance]
+  outputs: [total]
+```
+
+This stream aggregation generates `http_request_duration_seconds_bucket:5m_without_instance_total` output series according to [output metric naming](#output-metric-names).
+Then these series can be used in [alerting rules](https://docs.victoriametrics.com/vmalert.html#alerting-rules):
+
+```metricsql
+histogram_quantile(0.99, last_over_time(http_request_duration_seconds_bucket:5m_without_instance_total[5m])) > 0.5
+```
+
+This query is executed much faster than the original query, because it needs to scan much lower number of time series.
+
+See [the list of aggregate output](#aggregation-outputs), which can be specified at `output` field.
+See also [aggregating by labels](#aggregating-by-labels).
+
+
+### Reducing the number of stored samples
+
+If per-[series](https://docs.victoriametrics.com/keyConcepts.html#time-series) samples are ingested at high frequency,
+then this may result in high disk space usage, since too much data must be stored to disk. This also may result
+in slow queries, since too much data must be processed during queries.
+
+This can be fixed with the stream aggregation by increasing the interval between per-series samples stored in the database.
+
+For example, the following [stream aggregation config](#stream-aggregation-config) reduces the frequency of input samples
+to one sample per 5 minutes per each input time series (this operation is also known as downsampling):
+
+```yaml
+  # Aggregate metrics ending with _total with `total` output.
+  # See https://docs.victoriametrics.com/stream-aggregation.html#aggregation-outputs
+- match: '{__name__=~".+_total"}'
+  interval: 5m
+  outputs: [total]
+
+  # Downsample other metrics with `count_samples`, `sum_samples`, `min` and `max` outputs
+  # See https://docs.victoriametrics.com/stream-aggregation.html#aggregation-outputs
+- match: '{__name__!~".+_total"}'
+  interval: 5m
+  outputs: [count_samples, sum_samples, min, max]
+```
+
+The aggregated output metrics have the following names according to [output metric naming](#output-metric-names):
+
+```
+# For input metrics ending with _total
+some_metric_total:5m_total
+
+# For input metrics not ending with _total
+some_metric:5m_count_samples
+some_metric:5m_sum_samples
+some_metric:5m_min
+some_metric:5m_max
+```
+
+See [the list of aggregate output](#aggregation-outputs), which can be specified at `output` field.
+See also [aggregating by labels](#aggregating-by-labels).
+
+### Reducing the number of stored series
+
+Sometimes apps may generate too many [time series](https://docs.victoriametrics.com/keyConcepts.html#time-series).
+For example, the `http_requests_total` metric may have `path` or `user` label with too big number of unique values.
+In this case the following stream aggregation can be used for reducing the number metrics stored in VictoriaMetrics:
+
+```yaml
+- match: 'http_requests_total'
+  interval: 30s
+  without: [path, user]
+  outputs: [total]
+```
+
+This config specifies labels, which must be removed from the aggregate outpit, in the `without` list.
+See [these docs](#aggregating-by-labels) for more details.
+
+The aggregated output metric has the following name according to [output metric naming](#output-metric-names):
+
+```
+http_requests_total:30s_without_path_user_total
+```
+
+See [the list of aggregate output](#aggregation-outputs), which can be specified at `output` field.
+
+
+### Counting input samples
+
+If the monitored app generates event-based metrics, then it may be useful to count the number of such metrics
+at stream aggregation level.
+
+For example, if an advertising server generates `hits{some="labels"} 1` and `clicks{some="labels"} 1` metrics
+per each incoming hit and click, then the following [stream aggregation config](#stream-aggregation-config)
+can be used for counting these metrics per every 30 second interval:
+
+```yml
+- match: '{__name__=~"hits|clicks"}'
+  interval: 30s
+  outputs: [count_samples]
+```
+
+This config generates the following output metrics for `hits` and `clicks` input metrics
+according to [output metric naming](#output-metric-names):
+
+```
+hits:30s_count_samples count1
+clicks:30s_count_samples count2
+```
+
+See [the list of aggregate output](#aggregation-outputs), which can be specified at `output` field.
+See also [aggregating by labels](#aggregating-by-labels).
+
+
+### Summing input metrics
+
+If the monitored app calulates some events and then sends the calculated number of events to VictoriaMetrics
+at irregular intervals or at too high frequency, then stream aggregation can be used for summing such events
+and writing the aggregate sums to the storage at regular intervals.
+
+For example, if an advertising server generates `hits{some="labels} N` and `clicks{some="labels"} M` metrics
+at irregular intervals, then the following [stream aggregation config](#stream-aggregation-config)
+can be used for summing these metrics per every minute:
+
+```yml
+- match: '{__name__=~"hits|clicks"}'
+  interval: 1m
+  outputs: [sum_samples]
+```
+
+This config generates the following output metrics according to [output metric naming](#output-metric-names):
+
+```
+hits:1m_sum_samples sum1
+clicks:1m_sum_samples sum2
+```
+
+See [the list of aggregate output](#aggregation-outputs), which can be specified at `output` field.
+See also [aggregating by labels](#aggregating-by-labels).
+
+
+### Quantiles over input metrics
+
+If the monitored app generates measurement metrics per each request, then it may be useful to calculate
+the pre-defined set of [percentiles](https://en.wikipedia.org/wiki/Percentile) over these measurements.
+
+For example, if the monitored app generates `request_duration_seconds N` and `response_size_bytes M` metrics
+per each incoming request, then the following [stream aggregation config](#stream-aggregation-config)
+can be used for calculating 50th and 99th percentiles for these metrics every 30 seconds:
+
+```yaml
+- match: '{__name__=~"request_duration_seconds|response_size_bytes"}'
+  interval: 30s
+  outputs: ["quantiles(0.50, 0.99)"]
+```
+
+This config generates the following output metrics according to [output metric naming](#output-metric-names):
+
+```
+request_duration_seconds:30s_quantiles{quantile="0.50"} value1
+request_duration_seconds:30s_quantiles{quantile="0.99"} value2
+
+response_size_bytes:30s_quantiles{quantile="0.50"} value1
+response_size_bytes:30s_quantiles{quantile="0.99"} value2
+```
+
+See [the list of aggregate output](#aggregation-outputs), which can be specified at `output` field.
+See also [histograms over input metrics](#histograms-over-input-metrics) and [aggregating by labels](#aggregating-by-labels).
+
+### Histograms over input metrics
+
+If the monitored app generates measurement metrics per each request, then it may be useful to calculate
+a [histogram](https://docs.victoriametrics.com/keyConcepts.html#histogram) over these metrics.
+
+For example, if the monitored app generates `request_duration_seconds N` and `response_size_bytes M` metrics
+per each incoming request, then the following [stream aggregation config](#stream-aggregation-config)
+can be used for calculating [VictoriaMetrics histogram buckets](https://valyala.medium.com/improving-histogram-usability-for-prometheus-and-grafana-bc7e5df0e350)
+for these metrics every 60 seconds:
+
+```yaml
+- match: '{__name__=~"request_duration_seconds|response_size_bytes"}'
+  interval: 60s
+  outputs: [histogram_bucket]
+```
+
+This config generates the following output metrics according to [output metric naming](#output-metric-names).
+
+```
+request_duration_seconds:60s_histogram_bucket{vmrange="start1...end1"} count1
+request_duration_seconds:60s_histogram_bucket{vmrange="start2...end2"} count2
+...
+request_duration_seconds:60s_histogram_bucket{vmrange="startN...endN"} countN
+
+response_size_bytes:60s_histogram_bucket{vmrange="start1...end1"} count1
+response_size_bytes:60s_histogram_bucket{vmrange="start2...end2"} count2
+...
+response_size_bytes:60s_histogram_bucket{vmrange="startN...endN"} countN
+```
+
+The resulting histogram buckets can be queried with [MetricsQL](https://docs.victoriametrics.com/MetricsQL.html) in the following ways:
+
+1. An estimated 50th and 99th [percentiles](https://en.wikipedia.org/wiki/Percentile) of the request duration over the last hour:
+
+   ```metricsql
+   histogram_quantiles("quantile", 0.50, 0.99, sum(increase(request_duration_seconds:60s_histogram_bucket[1h])) by (vmrange))
+   ```
+
+   This query uses [histogram_quantiles](https://docs.victoriametrics.com/MetricsQL.html#histogram_quantiles) function.
+
+2. An estimated [standard deviation](https://en.wikipedia.org/wiki/Standard_deviation) of the request duration over the last hour:
+
+   ```metricsql
+   histogram_stddev(sum(increase(request_duration_seconds:60s_histogram_bucket[1h])) by (vmrange))
+   ```
+
+   This query uses [histogram_stddev](https://docs.victoriametrics.com/MetricsQL.html#histogram_stddev) function.
+
+3. An estimated share of requests with the duration smaller than `0.5s` over the last hour:
+
+   ```metricsql
+   histogram_share(0.5, sum(increase(request_duration_seconds:60s_histogram_bucket[1h])) by (vmrange))
+   ```
+
+   This query uses [histogram_share](https://docs.victoriametrics.com/MetricsQL.html#histogram_share) function.
+
+See [the list of aggregate output](#aggregation-outputs), which can be specified at `output` field.
+See also [quantiles over input metrics](#quantiles-over-input-metrics) and [aggregating by labels](#aggregating-by-labels).
+
+
+## Output metric names
+
+Output metric names for stream aggregation are constructed according to the following pattern:
+
+```
+<metric_name>:<interval>[_by_<by_labels>][_without_<without_labels>]_<output>
+```
+
+- `<metric_name>` is the original metric name.
+- `<interval>` is the interval specified in the [stream aggregation config](#stream-aggregation-config).
+- `<by_labels>` is `_`-delimited list of `by` labels specified in the [stream aggregation config](#stream-aggregation-config).
+  If the `by` list is missing in the config, then the `_by_<by_labels>` part isn't included in the output metric name.
+- `<without_labels>` is an optional `_`-delimited list of `without` labels specified in the [stream aggregation config](#stream-aggregation-config).
+  If the `without` list is missing in the config, then the `_without_<without_labels>` part isn't included in the output metric name.
+- `<output>` is the aggregate used for constucting the output metric. The aggregate name is taken from the `outputs` list
+  at the corresponding [stream aggregation config](#stream-aggregation-config).
+
+Both input and ouput metric names can be modified if needed via relabeling according to [these docs](#relabeling).
+
+
+## Relabeling
+
+It is possible to apply [arbitrary relabeling](https://docs.victoriametrics.com/vmagent.html#relabeling) to input and output metrics
+during stream aggregation via `input_relabel_configs` and `output_relabel_config` options in [stream aggregation config](#stream-aggregation-config).
+
+For example, the following config removes the `:1m_sum_samples` suffix added [to the output metric name](#output-metric-names):
+
+```yml
+- interval: 1m
+  outputs: [sum_samples]
+  output_relabel_configs:
+  - source_labels: [__name__]
+    target_label: __name__
+    regex: "(.+):.+"
+```
+
+## Aggregation outputs
+
+The following aggregation outputs are supported in the `outputs` list of the [stream aggregation config](#stream-aggregation-config):
+
+* `total` generates output [counter](https://docs.victoriametrics.com/keyConcepts.html#counter) by summing the input counters.
+  The `total` handler properly handles input counter resets.
+  The `total` handler returns garbage when something other than [counter](https://docs.victoriametrics.com/keyConcepts.html#counter) is passed to the input.
+* `increase` returns the increase of input [counters](https://docs.victoriametrics.com/keyConcepts.html#counter).
+  The `increase` handler properly handles the input counter resets.
+  The `increase` handler returns garbage when something other than [counter](https://docs.victoriametrics.com/keyConcepts.html#counter) is passed to the input.
+* `count_series` counts the number of unique [time series](https://docs.victoriametrics.com/keyConcepts.html#time-series).
+* `count_samples` counts the number of input [samples](https://docs.victoriametrics.com/keyConcepts.html#raw-samples).
+* `sum_samples` sums input [sample values](https://docs.victoriametrics.com/keyConcepts.html#raw-samples).
+* `last` returns the last input [sample value](https://docs.victoriametrics.com/keyConcepts.html#raw-samples).
+* `min` returns the minimum input [sample value](https://docs.victoriametrics.com/keyConcepts.html#raw-samples).
+* `max` returns the maximum input [sample value](https://docs.victoriametrics.com/keyConcepts.html#raw-samples).
+* `avg` returns the average input [sample value](https://docs.victoriametrics.com/keyConcepts.html#raw-samples).
+* `stddev` returns [standard deviation](https://en.wikipedia.org/wiki/Standard_deviation) for the input [sample values](https://docs.victoriametrics.com/keyConcepts.html#raw-samples).
+* `stdvar` returns [standard variance](https://en.wikipedia.org/wiki/Variance) for the input [sample values](https://docs.victoriametrics.com/keyConcepts.html#raw-samples).
+* `histogram_bucket` returns [VictoriaMetrics histogram buckets](https://valyala.medium.com/improving-histogram-usability-for-prometheus-and-grafana-bc7e5df0e350)
+  for the input [sample values](https://docs.victoriametrics.com/keyConcepts.html#raw-samples).
+* `quantiles(phi1, ..., phiN)` returns [percentiles](https://en.wikipedia.org/wiki/Percentile) for the given `phi*`
+  over the input [sample values](https://docs.victoriametrics.com/keyConcepts.html#raw-samples).
+  The `phi` must be in the range `[0..1]`, where `0` means `0th` percentile, while `1` means `100th` percentile.
+
+The aggregations are calculated during the `interval` specified in the [config](#stream-aggregation-config)
+and then sent to the storage.
+
+If `by` and `without` lists are specified in the [config](#stream-aggregation-config),
+then the [aggregation by labels](#aggregating-by-labels) is performed additionally to aggregation by `interval`.
+
+
+## Aggregating by labels
+
+All the labels for the input metrics are preserved by default in the output metrics. For example,
+the input metric `foo{app="bar",instance="host1"}` results to the output metric `foo:1m_sum_samples{app="bar",instance="host1"}`
+when the following [stream aggregation config](#stream-aggregation-config) is used:
+
+```yaml
+- interval: 1m
+  outputs: [sum_samples]
+```
+
+The input labels can be removed via `without` list specified in the config. For example, the following config
+removes the `instance` label from output metrics by summing input samples across all the instances:
+
+```yaml
+- interval: 1m
+  without: [instance]
+  outputs: [sum_samples]
+```
+
+In this case the `foo{app="bar",instance="..."}` input metrics are transformed into `foo:1m_without_instance_sum_samples{app="bar"}`
+output metric.
+
+It is possible specifying the exact list of labels in the output metrics via `by` list.
+For example, the following config sums input samples by the `app` label:
+
+```yaml
+- interval: 1m
+  by: [app]
+  outputs: [sum_samples]
+```
+
+In this case the `foo{app="bar",instance="..."}` input metrics are transformed into `foo:1m_by_app_sum_samples{app="bar"}`
+output metric.
+
+
+## Stream aggregation config
+
+Below is the format for stream aggregation config file, which may be referred via `-remoteWrite.streamAggr.config` command-line flag
+at [vmagent](https://docs.victoriametrics.com/vmagent.html) or via `-streamAggr.config` command-line flag
+at [single-node VictoriaMetrics](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html):
+
+```yaml
+  # match is an optional filter for incoming samples to aggregate.
+  # It can contain arbitrary Prometheus series selector
+  # according to https://docs.victoriametrics.com/keyConcepts.html#filtering .
+  # If match is missing, then all the incoming samples are aggregated.
+- match: 'http_request_duration_seconds_bucket{env=~"prod|staging"}'
+
+  # interval is the interval for the aggregation.
+  # The aggregated stats is sent to remote storage once per interval.
+  interval: 1m
+
+  # without is an optional list of labels, which must be removed from the output aggregation.
+  # See https://docs.victoriametrics.com/stream-aggregation.html#aggregating-by-labels
+  without: [instance]
+
+  # by is an optioanl list of labels, which must be preserved in the output aggregation.
+  # See https://docs.victoriametrics.com/stream-aggregation.html#aggregating-by-labels
+  # by: [job, vmrange]
+
+  # outputs is the list of aggregations to perform on the input data.
+  # See https://docs.victoriametrics.com/stream-aggregation.html#aggregation-outputs
+  outputs: [total]
+
+  # input_relabel_configs is an optional relabeling rules,
+  # which are applied to the incoming samples after they pass the match filter
+  # and before being aggregated.
+  # See https://docs.victoriametrics.com/stream-aggregation.html#relabeling
+  input_relabel_configs:
+  - target_label: vmaggr
+    replacement: before
+
+  # output_relabel_configs is an optional relabeling rules,
+  # which are applied to the aggregated output metrics.
+  output_relabel_configs:
+  - target_label: vmaggr
+    replacement: after
+```
+
+The file can contain multiple aggregation configs. The aggregation is performed independently
+per each specified config entry.
diff --git a/docs/vmagent.md b/docs/vmagent.md
index 9b25c8700..ff853c436 100644
--- a/docs/vmagent.md
+++ b/docs/vmagent.md
@@ -28,8 +28,8 @@ additionally to [discovering Prometheus-compatible targets and scraping metrics
   see [these docs](https://docs.victoriametrics.com/#how-to-scrape-prometheus-exporters-such-as-node-exporter).
 * Can add, remove and modify labels (aka tags) via Prometheus relabeling. Can filter data before sending it to remote storage. See [these docs](#relabeling) for details.
 * Can accept data via all the ingestion protocols supported by VictoriaMetrics - see [these docs](#how-to-push-data-to-vmagent).
-* Can replicate collected metrics simultaneously to multiple remote storage systems -
-  see [these docs](#replication-and-high-availability).
+* Can aggregate incoming samples by time and by labels before sending them to remote storage - see [these docs](https://docs.victoriametrics.com/stream-aggregation.html).
+* Can replicate collected metrics simultaneously to multiple remote storage systems - see [these docs](#replication-and-high-availability).
 * Works smoothly in environments with unstable connections to remote storage. If the remote storage is unavailable, the collected metrics
   are buffered at `-remoteWrite.tmpDataPath`. The buffered metrics are sent to remote storage as soon as the connection
   to the remote storage is repaired. The maximum disk usage for the buffer can be limited with `-remoteWrite.maxDiskUsagePerURL`.
@@ -130,6 +130,12 @@ If you use Prometheus only for scraping metrics from various targets and forward
 then `vmagent` can replace Prometheus. Typically, `vmagent` requires lower amounts of RAM, CPU and network bandwidth compared with Prometheus.
 See [these docs](#how-to-collect-metrics-in-prometheus-format) for details.
 
+### Statsd alternative
+
+`vmagent` can be used as an alternative to [statsd](https://github.com/statsd/statsd)
+when [stream aggregation](https://docs.victoriametrics.com/stream-aggregation.html) is enabled.
+See [these docs](https://docs.victoriametrics.com/stream-aggregation.html#statsd-alternative) for details.
+
 ### Flexible metrics relay
 
 `vmagent` can accept metrics in [various popular data ingestion protocols](#how-to-push-data-to-vmagent), apply [relabeling](#relabeling)
diff --git a/docs/vmalert.md b/docs/vmalert.md
index 1afa9a977..08e33b64d 100644
--- a/docs/vmalert.md
+++ b/docs/vmalert.md
@@ -73,16 +73,17 @@ Then configure `vmalert` accordingly:
     -external.label=replica=a                # Multiple external labels may be set
 ```
 
-Note there's a separate `remoteWrite.url` to allow writing results of
+Note there's a separate `-remoteWrite.url` command-line flag to allow writing results of
 alerting/recording rules into a different storage than the initial data that's
 queried. This allows using `vmalert` to aggregate data from a short-term,
 high-frequency, high-cardinality storage into a long-term storage with
 decreased cardinality and a bigger interval between samples.
+See also [stream aggregation](https://docs.victoriametrics.com/stream-aggregation.html).
 
 See the full list of configuration flags in [configuration](#configuration) section.
 
 If you run multiple `vmalert` services for the same datastore or AlertManager - do not forget
-to specify different `external.label` flags in order to define which `vmalert` generated rules or alerts.
+to specify different `-external.label` command-line flags in order to define which `vmalert` generated rules or alerts.
 
 Configuration for [recording](https://prometheus.io/docs/prometheus/latest/configuration/recording_rules/)
 and [alerting](https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/) rules is very
@@ -518,8 +519,8 @@ groups:
       expr: avg_over_time(http_requests[5m])
 ```
 
-Ability of `vmalert` to be configured with different `datasource.url` and `remoteWrite.url` allows
-reading data from one data source and backfilling results to another. This helps to build a system
+Ability of `vmalert` to be configured with different `-datasource.url` and `-remoteWrite.url` command-line flags
+allows reading data from one data source and backfilling results to another. This helps to build a system
 for aggregating and downsampling the data.
 
 The following example shows how to build a topology where `vmalert` will process data from one cluster
@@ -543,7 +544,7 @@ Please note, [replay](#rules-backfilling) feature may be used for transforming h
 
 Flags `-remoteRead.url` and `-notifier.url` are omitted since we assume only recording rules are used.
 
-See also [downsampling docs](https://docs.victoriametrics.com/#downsampling).
+See also [stream aggregation](https://docs.victoriametrics.com/stream-aggregation.html) and [downsampling](https://docs.victoriametrics.com/#downsampling).
 
 #### Multiple remote writes
 
diff --git a/lib/streamaggr/avg.go b/lib/streamaggr/avg.go
new file mode 100644
index 000000000..ce9becc82
--- /dev/null
+++ b/lib/streamaggr/avg.go
@@ -0,0 +1,74 @@
+package streamaggr
+
+import (
+	"sync"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
+)
+
+// avgAggrState calculates output=avg, e.g. the average value over input samples.
+type avgAggrState struct {
+	m sync.Map
+}
+
+type avgStateValue struct {
+	mu      sync.Mutex
+	sum     float64
+	count   int64
+	deleted bool
+}
+
+func newAvgAggrState() *avgAggrState {
+	return &avgAggrState{}
+}
+
+func (as *avgAggrState) pushSample(inputKey, outputKey string, value float64) {
+again:
+	v, ok := as.m.Load(outputKey)
+	if !ok {
+		// The entry is missing in the map. Try creating it.
+		v = &avgStateValue{
+			sum:   value,
+			count: 1,
+		}
+		vNew, loaded := as.m.LoadOrStore(outputKey, v)
+		if !loaded {
+			// The entry has been successfully stored
+			return
+		}
+		// Update the entry created by a concurrent goroutine.
+		v = vNew
+	}
+	sv := v.(*avgStateValue)
+	sv.mu.Lock()
+	deleted := sv.deleted
+	if !deleted {
+		sv.sum += value
+		sv.count++
+	}
+	sv.mu.Unlock()
+	if deleted {
+		// The entry has been deleted by the concurrent call to appendSeriesForFlush
+		// Try obtaining and updating the entry again.
+		goto again
+	}
+}
+
+func (as *avgAggrState) appendSeriesForFlush(ctx *flushCtx) {
+	currentTimeMsec := int64(fasttime.UnixTimestamp()) * 1000
+	m := &as.m
+	m.Range(func(k, v interface{}) bool {
+		// Atomically delete the entry from the map, so new entry is created for the next flush.
+		m.Delete(k)
+
+		sv := v.(*avgStateValue)
+		sv.mu.Lock()
+		avg := sv.sum / float64(sv.count)
+		// Mark the entry as deleted, so it won't be updated anymore by concurrent pushSample() calls.
+		sv.deleted = true
+		sv.mu.Unlock()
+		key := k.(string)
+		ctx.appendSeries(key, "avg", currentTimeMsec, avg)
+		return true
+	})
+}
diff --git a/lib/streamaggr/count_samples.go b/lib/streamaggr/count_samples.go
new file mode 100644
index 000000000..ddf582e8c
--- /dev/null
+++ b/lib/streamaggr/count_samples.go
@@ -0,0 +1,71 @@
+package streamaggr
+
+import (
+	"sync"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
+)
+
+// countSamplesAggrState calculates output=countSamples, e.g. the count of input samples.
+type countSamplesAggrState struct {
+	m sync.Map
+}
+
+type countSamplesStateValue struct {
+	mu      sync.Mutex
+	n       uint64
+	deleted bool
+}
+
+func newCountSamplesAggrState() *countSamplesAggrState {
+	return &countSamplesAggrState{}
+}
+
+func (as *countSamplesAggrState) pushSample(inputKey, outputKey string, value float64) {
+again:
+	v, ok := as.m.Load(outputKey)
+	if !ok {
+		// The entry is missing in the map. Try creating it.
+		v = &countSamplesStateValue{
+			n: 1,
+		}
+		vNew, loaded := as.m.LoadOrStore(outputKey, v)
+		if !loaded {
+			// The new entry has been successfully created.
+			return
+		}
+		// Use the entry created by a concurrent goroutine.
+		v = vNew
+	}
+	sv := v.(*countSamplesStateValue)
+	sv.mu.Lock()
+	deleted := sv.deleted
+	if !deleted {
+		sv.n++
+	}
+	sv.mu.Unlock()
+	if deleted {
+		// The entry has been deleted by the concurrent call to appendSeriesForFlush
+		// Try obtaining and updating the entry again.
+		goto again
+	}
+}
+
+func (as *countSamplesAggrState) appendSeriesForFlush(ctx *flushCtx) {
+	currentTimeMsec := int64(fasttime.UnixTimestamp()) * 1000
+	m := &as.m
+	m.Range(func(k, v interface{}) bool {
+		// Atomically delete the entry from the map, so new entry is created for the next flush.
+		m.Delete(k)
+
+		sv := v.(*countSamplesStateValue)
+		sv.mu.Lock()
+		n := sv.n
+		// Mark the entry as deleted, so it won't be updated anymore by concurrent pushSample() calls.
+		sv.deleted = true
+		sv.mu.Unlock()
+		key := k.(string)
+		ctx.appendSeries(key, "count_samples", currentTimeMsec, float64(n))
+		return true
+	})
+}
diff --git a/lib/streamaggr/count_series.go b/lib/streamaggr/count_series.go
new file mode 100644
index 000000000..ffb8e5578
--- /dev/null
+++ b/lib/streamaggr/count_series.go
@@ -0,0 +1,78 @@
+package streamaggr
+
+import (
+	"sync"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
+)
+
+// countSeriesAggrState calculates output=count_series, e.g. the number of unique series.
+type countSeriesAggrState struct {
+	m sync.Map
+}
+
+type countSeriesStateValue struct {
+	mu            sync.Mutex
+	countedSeries map[string]struct{}
+	n             uint64
+	deleted       bool
+}
+
+func newCountSeriesAggrState() *countSeriesAggrState {
+	return &countSeriesAggrState{}
+}
+
+func (as *countSeriesAggrState) pushSample(inputKey, outputKey string, value float64) {
+again:
+	v, ok := as.m.Load(outputKey)
+	if !ok {
+		// The entry is missing in the map. Try creating it.
+		v = &countSeriesStateValue{
+			countedSeries: map[string]struct{}{
+				inputKey: {},
+			},
+			n: 1,
+		}
+		vNew, loaded := as.m.LoadOrStore(outputKey, v)
+		if !loaded {
+			// The entry has been added to the map.
+			return
+		}
+		// Update the entry created by a concurrent goroutine.
+		v = vNew
+	}
+	sv := v.(*countSeriesStateValue)
+	sv.mu.Lock()
+	deleted := sv.deleted
+	if !deleted {
+		if _, ok := sv.countedSeries[inputKey]; !ok {
+			sv.countedSeries[inputKey] = struct{}{}
+			sv.n++
+		}
+	}
+	sv.mu.Unlock()
+	if deleted {
+		// The entry has been deleted by the concurrent call to appendSeriesForFlush
+		// Try obtaining and updating the entry again.
+		goto again
+	}
+}
+
+func (as *countSeriesAggrState) appendSeriesForFlush(ctx *flushCtx) {
+	currentTimeMsec := int64(fasttime.UnixTimestamp()) * 1000
+	m := &as.m
+	m.Range(func(k, v interface{}) bool {
+		// Atomically delete the entry from the map, so new entry is created for the next flush.
+		m.Delete(k)
+
+		sv := v.(*countSeriesStateValue)
+		sv.mu.Lock()
+		n := sv.n
+		// Mark the entry as deleted, so it won't be updated anymore by concurrent pushSample() calls.
+		sv.deleted = true
+		sv.mu.Unlock()
+		key := k.(string)
+		ctx.appendSeries(key, "count_series", currentTimeMsec, float64(n))
+		return true
+	})
+}
diff --git a/lib/streamaggr/histogram_bucket.go b/lib/streamaggr/histogram_bucket.go
new file mode 100644
index 000000000..b3c087332
--- /dev/null
+++ b/lib/streamaggr/histogram_bucket.go
@@ -0,0 +1,102 @@
+package streamaggr
+
+import (
+	"sync"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
+	"github.com/VictoriaMetrics/metrics"
+)
+
+// histogramBucketAggrState calculates output=histogramBucket, e.g. VictoriaMetrics histogram over input samples.
+type histogramBucketAggrState struct {
+	m sync.Map
+
+	ignoreInputDeadline uint64
+	intervalSecs        uint64
+}
+
+type histogramBucketStateValue struct {
+	mu             sync.Mutex
+	h              metrics.Histogram
+	deleteDeadline uint64
+	deleted        bool
+}
+
+func newHistogramBucketAggrState(interval time.Duration) *histogramBucketAggrState {
+	intervalSecs := uint64(interval.Seconds() + 1)
+	return &histogramBucketAggrState{
+		intervalSecs: intervalSecs,
+	}
+}
+
+func (as *histogramBucketAggrState) pushSample(inputKey, outputKey string, value float64) {
+	currentTime := fasttime.UnixTimestamp()
+	deleteDeadline := currentTime + 2*as.intervalSecs
+
+again:
+	v, ok := as.m.Load(outputKey)
+	if !ok {
+		// The entry is missing in the map. Try creating it.
+		v = &histogramBucketStateValue{}
+		vNew, loaded := as.m.LoadOrStore(outputKey, v)
+		if loaded {
+			// Use the entry created by a concurrent goroutine.
+			v = vNew
+		}
+	}
+	sv := v.(*histogramBucketStateValue)
+	sv.mu.Lock()
+	deleted := sv.deleted
+	if !deleted {
+		sv.h.Update(value)
+		sv.deleteDeadline = deleteDeadline
+	}
+	sv.mu.Unlock()
+	if deleted {
+		// The entry has been deleted by the concurrent call to appendSeriesForFlush
+		// Try obtaining and updating the entry again.
+		goto again
+	}
+}
+
+func (as *histogramBucketAggrState) removeOldEntries(currentTime uint64) {
+	m := &as.m
+	m.Range(func(k, v interface{}) bool {
+		sv := v.(*histogramBucketStateValue)
+
+		sv.mu.Lock()
+		deleted := currentTime > sv.deleteDeadline
+		if deleted {
+			// Mark the current entry as deleted
+			sv.deleted = deleted
+		}
+		sv.mu.Unlock()
+
+		if deleted {
+			m.Delete(k)
+		}
+		return true
+	})
+}
+
+func (as *histogramBucketAggrState) appendSeriesForFlush(ctx *flushCtx) {
+	currentTime := fasttime.UnixTimestamp()
+	currentTimeMsec := int64(currentTime) * 1000
+
+	as.removeOldEntries(currentTime)
+
+	m := &as.m
+	m.Range(func(k, v interface{}) bool {
+		sv := v.(*histogramBucketStateValue)
+		sv.mu.Lock()
+		if !sv.deleted {
+			key := k.(string)
+			sv.h.VisitNonZeroBuckets(func(vmrange string, count uint64) {
+				ctx.appendSeriesWithExtraLabel(key, "histogram_bucket", currentTimeMsec, float64(count), "vmrange", vmrange)
+			})
+		}
+		sv.mu.Unlock()
+		return true
+	})
+}
diff --git a/lib/streamaggr/increase.go b/lib/streamaggr/increase.go
new file mode 100644
index 000000000..0161d60f1
--- /dev/null
+++ b/lib/streamaggr/increase.go
@@ -0,0 +1,129 @@
+package streamaggr
+
+import (
+	"sync"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
+)
+
+// increaseAggrState calculates output=increase, e.g. the increase over input counters.
+type increaseAggrState struct {
+	m sync.Map
+
+	ignoreInputDeadline uint64
+	intervalSecs        uint64
+}
+
+type increaseStateValue struct {
+	mu             sync.Mutex
+	lastValues     map[string]*lastValueState
+	total          float64
+	increase       float64
+	deleteDeadline uint64
+	deleted        bool
+}
+
+func newIncreaseAggrState(interval time.Duration) *increaseAggrState {
+	currentTime := fasttime.UnixTimestamp()
+	intervalSecs := uint64(interval.Seconds() + 1)
+	return &increaseAggrState{
+		ignoreInputDeadline: currentTime + intervalSecs,
+		intervalSecs:        intervalSecs,
+	}
+}
+
+func (as *increaseAggrState) pushSample(inputKey, outputKey string, value float64) {
+	currentTime := fasttime.UnixTimestamp()
+	deleteDeadline := currentTime + 2*as.intervalSecs
+
+again:
+	v, ok := as.m.Load(outputKey)
+	if !ok {
+		// The entry is missing in the map. Try creating it.
+		v = &increaseStateValue{
+			lastValues: make(map[string]*lastValueState),
+		}
+		vNew, loaded := as.m.LoadOrStore(outputKey, v)
+		if loaded {
+			// Use the entry created by a concurrent goroutine.
+			v = vNew
+		}
+	}
+	sv := v.(*increaseStateValue)
+	sv.mu.Lock()
+	deleted := sv.deleted
+	if !deleted {
+		lv, ok := sv.lastValues[inputKey]
+		if !ok {
+			lv = &lastValueState{}
+			sv.lastValues[inputKey] = lv
+		}
+		d := value
+		if ok && lv.value <= value {
+			d = value - lv.value
+		}
+		if ok || currentTime > as.ignoreInputDeadline {
+			sv.total += d
+		}
+		lv.value = value
+		lv.deleteDeadline = deleteDeadline
+		sv.deleteDeadline = deleteDeadline
+	}
+	sv.mu.Unlock()
+	if deleted {
+		// The entry has been deleted by the concurrent call to appendSeriesForFlush
+		// Try obtaining and updating the entry again.
+		goto again
+	}
+}
+
+func (as *increaseAggrState) removeOldEntries(currentTime uint64) {
+	m := &as.m
+	m.Range(func(k, v interface{}) bool {
+		sv := v.(*increaseStateValue)
+
+		sv.mu.Lock()
+		deleted := currentTime > sv.deleteDeadline
+		if deleted {
+			// Mark the current entry as deleted
+			sv.deleted = deleted
+		} else {
+			// Delete outdated entries in sv.lastValues
+			m := sv.lastValues
+			for k1, v1 := range m {
+				if currentTime > v1.deleteDeadline {
+					delete(m, k1)
+				}
+			}
+		}
+		sv.mu.Unlock()
+
+		if deleted {
+			m.Delete(k)
+		}
+		return true
+	})
+}
+
+func (as *increaseAggrState) appendSeriesForFlush(ctx *flushCtx) {
+	currentTime := fasttime.UnixTimestamp()
+	currentTimeMsec := int64(currentTime) * 1000
+
+	as.removeOldEntries(currentTime)
+
+	m := &as.m
+	m.Range(func(k, v interface{}) bool {
+		sv := v.(*increaseStateValue)
+		sv.mu.Lock()
+		increase := sv.total
+		sv.total = 0
+		deleted := sv.deleted
+		sv.mu.Unlock()
+		if !deleted {
+			key := k.(string)
+			ctx.appendSeries(key, "increase", currentTimeMsec, increase)
+		}
+		return true
+	})
+}
diff --git a/lib/streamaggr/last.go b/lib/streamaggr/last.go
new file mode 100644
index 000000000..c81a41db6
--- /dev/null
+++ b/lib/streamaggr/last.go
@@ -0,0 +1,71 @@
+package streamaggr
+
+import (
+	"sync"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
+)
+
+// lastAggrState calculates output=last, e.g. the last value over input samples.
+type lastAggrState struct {
+	m sync.Map
+}
+
+type lastStateValue struct {
+	mu      sync.Mutex
+	last    float64
+	deleted bool
+}
+
+func newLastAggrState() *lastAggrState {
+	return &lastAggrState{}
+}
+
+func (as *lastAggrState) pushSample(inputKey, outputKey string, value float64) {
+again:
+	v, ok := as.m.Load(outputKey)
+	if !ok {
+		// The entry is missing in the map. Try creating it.
+		v = &lastStateValue{
+			last: value,
+		}
+		vNew, loaded := as.m.LoadOrStore(outputKey, v)
+		if !loaded {
+			// The new entry has been successfully created.
+			return
+		}
+		// Use the entry created by a concurrent goroutine.
+		v = vNew
+	}
+	sv := v.(*lastStateValue)
+	sv.mu.Lock()
+	deleted := sv.deleted
+	if !deleted {
+		sv.last = value
+	}
+	sv.mu.Unlock()
+	if deleted {
+		// The entry has been deleted by the concurrent call to appendSeriesForFlush
+		// Try obtaining and updating the entry again.
+		goto again
+	}
+}
+
+func (as *lastAggrState) appendSeriesForFlush(ctx *flushCtx) {
+	currentTimeMsec := int64(fasttime.UnixTimestamp()) * 1000
+	m := &as.m
+	m.Range(func(k, v interface{}) bool {
+		// Atomically delete the entry from the map, so new entry is created for the next flush.
+		m.Delete(k)
+
+		sv := v.(*lastStateValue)
+		sv.mu.Lock()
+		last := sv.last
+		// Mark the entry as deleted, so it won't be updated anymore by concurrent pushSample() calls.
+		sv.deleted = true
+		sv.mu.Unlock()
+		key := k.(string)
+		ctx.appendSeries(key, "last", currentTimeMsec, last)
+		return true
+	})
+}
diff --git a/lib/streamaggr/max.go b/lib/streamaggr/max.go
new file mode 100644
index 000000000..09122ee64
--- /dev/null
+++ b/lib/streamaggr/max.go
@@ -0,0 +1,73 @@
+package streamaggr
+
+import (
+	"sync"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
+)
+
+// maxAggrState calculates output=max, e.g. the maximum value over input samples.
+type maxAggrState struct {
+	m sync.Map
+}
+
+type maxStateValue struct {
+	mu      sync.Mutex
+	max     float64
+	deleted bool
+}
+
+func newMaxAggrState() *maxAggrState {
+	return &maxAggrState{}
+}
+
+func (as *maxAggrState) pushSample(inputKey, outputKey string, value float64) {
+again:
+	v, ok := as.m.Load(outputKey)
+	if !ok {
+		// The entry is missing in the map. Try creating it.
+		v = &maxStateValue{
+			max: value,
+		}
+		vNew, loaded := as.m.LoadOrStore(outputKey, v)
+		if !loaded {
+			// The new entry has been successfully created.
+			return
+		}
+		// Use the entry created by a concurrent goroutine.
+		v = vNew
+	}
+	sv := v.(*maxStateValue)
+	sv.mu.Lock()
+	deleted := sv.deleted
+	if !deleted {
+		if value > sv.max {
+			sv.max = value
+		}
+	}
+	sv.mu.Unlock()
+	if deleted {
+		// The entry has been deleted by the concurrent call to appendSeriesForFlush
+		// Try obtaining and updating the entry again.
+		goto again
+	}
+}
+
+func (as *maxAggrState) appendSeriesForFlush(ctx *flushCtx) {
+	currentTimeMsec := int64(fasttime.UnixTimestamp()) * 1000
+	m := &as.m
+	m.Range(func(k, v interface{}) bool {
+		// Atomically delete the entry from the map, so new entry is created for the next flush.
+		m.Delete(k)
+
+		sv := v.(*maxStateValue)
+		sv.mu.Lock()
+		max := sv.max
+		// Mark the entry as deleted, so it won't be updated anymore by concurrent pushSample() calls.
+		sv.deleted = true
+		sv.mu.Unlock()
+		key := k.(string)
+		ctx.appendSeries(key, "max", currentTimeMsec, max)
+		return true
+	})
+}
diff --git a/lib/streamaggr/min.go b/lib/streamaggr/min.go
new file mode 100644
index 000000000..e9e5dfcd2
--- /dev/null
+++ b/lib/streamaggr/min.go
@@ -0,0 +1,73 @@
+package streamaggr
+
+import (
+	"sync"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
+)
+
+// minAggrState calculates output=min, e.g. the minimum value over input samples.
+type minAggrState struct {
+	m sync.Map
+}
+
+type minStateValue struct {
+	mu      sync.Mutex
+	min     float64
+	deleted bool
+}
+
+func newMinAggrState() *minAggrState {
+	return &minAggrState{}
+}
+
+func (as *minAggrState) pushSample(inputKey, outputKey string, value float64) {
+again:
+	v, ok := as.m.Load(outputKey)
+	if !ok {
+		// The entry is missing in the map. Try creating it.
+		v = &minStateValue{
+			min: value,
+		}
+		vNew, loaded := as.m.LoadOrStore(outputKey, v)
+		if !loaded {
+			// The new entry has been successfully created.
+			return
+		}
+		// Use the entry created by a concurrent goroutine.
+		v = vNew
+	}
+	sv := v.(*minStateValue)
+	sv.mu.Lock()
+	deleted := sv.deleted
+	if !deleted {
+		if value < sv.min {
+			sv.min = value
+		}
+	}
+	sv.mu.Unlock()
+	if deleted {
+		// The entry has been deleted by the concurrent call to appendSeriesForFlush
+		// Try obtaining and updating the entry again.
+		goto again
+	}
+}
+
+func (as *minAggrState) appendSeriesForFlush(ctx *flushCtx) {
+	currentTimeMsec := int64(fasttime.UnixTimestamp()) * 1000
+	m := &as.m
+	m.Range(func(k, v interface{}) bool {
+		// Atomically delete the entry from the map, so new entry is created for the next flush.
+		m.Delete(k)
+
+		sv := v.(*minStateValue)
+		sv.mu.Lock()
+		min := sv.min
+		// Mark the entry as deleted, so it won't be updated anymore by concurrent pushSample() calls.
+		sv.deleted = true
+		sv.mu.Unlock()
+		key := k.(string)
+		ctx.appendSeries(key, "min", currentTimeMsec, min)
+		return true
+	})
+}
diff --git a/lib/streamaggr/quantiles.go b/lib/streamaggr/quantiles.go
new file mode 100644
index 000000000..ebd9590fb
--- /dev/null
+++ b/lib/streamaggr/quantiles.go
@@ -0,0 +1,87 @@
+package streamaggr
+
+import (
+	"strconv"
+	"sync"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
+	"github.com/valyala/histogram"
+)
+
+// quantilesAggrState calculates output=quantiles, e.g. the the given quantiles over the input samples.
+type quantilesAggrState struct {
+	m sync.Map
+
+	phis []float64
+}
+
+type quantilesStateValue struct {
+	mu      sync.Mutex
+	h       *histogram.Fast
+	deleted bool
+}
+
+func newQuantilesAggrState(phis []float64) *quantilesAggrState {
+	return &quantilesAggrState{
+		phis: phis,
+	}
+}
+
+func (as *quantilesAggrState) pushSample(inputKey, outputKey string, value float64) {
+again:
+	v, ok := as.m.Load(outputKey)
+	if !ok {
+		// The entry is missing in the map. Try creating it.
+		h := histogram.GetFast()
+		v = &quantilesStateValue{
+			h: h,
+		}
+		vNew, loaded := as.m.LoadOrStore(outputKey, v)
+		if loaded {
+			// Use the entry created by a concurrent goroutine.
+			histogram.PutFast(h)
+			v = vNew
+		}
+	}
+	sv := v.(*quantilesStateValue)
+	sv.mu.Lock()
+	deleted := sv.deleted
+	if !deleted {
+		sv.h.Update(value)
+	}
+	sv.mu.Unlock()
+	if deleted {
+		// The entry has been deleted by the concurrent call to appendSeriesForFlush
+		// Try obtaining and updating the entry again.
+		goto again
+	}
+}
+
+func (as *quantilesAggrState) appendSeriesForFlush(ctx *flushCtx) {
+	currentTimeMsec := int64(fasttime.UnixTimestamp()) * 1000
+	m := &as.m
+	phis := as.phis
+	var quantiles []float64
+	var b []byte
+	m.Range(func(k, v interface{}) bool {
+		// Atomically delete the entry from the map, so new entry is created for the next flush.
+		m.Delete(k)
+
+		sv := v.(*quantilesStateValue)
+		sv.mu.Lock()
+		quantiles = sv.h.Quantiles(quantiles[:0], phis)
+		histogram.PutFast(sv.h)
+		// Mark the entry as deleted, so it won't be updated anymore by concurrent pushSample() calls.
+		sv.deleted = true
+		sv.mu.Unlock()
+
+		key := k.(string)
+		for i, quantile := range quantiles {
+			b = strconv.AppendFloat(b[:0], phis[i], 'g', -1, 64)
+			phiStr := bytesutil.InternBytes(b)
+			ctx.appendSeriesWithExtraLabel(key, "quantiles", currentTimeMsec, quantile, "quantile", phiStr)
+		}
+		return true
+	})
+}
diff --git a/lib/streamaggr/stddev.go b/lib/streamaggr/stddev.go
new file mode 100644
index 000000000..107c78896
--- /dev/null
+++ b/lib/streamaggr/stddev.go
@@ -0,0 +1,74 @@
+package streamaggr
+
+import (
+	"math"
+	"sync"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
+)
+
+// stddevAggrState calculates output=stddev, e.g. the average value over input samples.
+type stddevAggrState struct {
+	m sync.Map
+}
+
+type stddevStateValue struct {
+	mu      sync.Mutex
+	count   float64
+	avg     float64
+	q       float64
+	deleted bool
+}
+
+func newStddevAggrState() *stddevAggrState {
+	return &stddevAggrState{}
+}
+
+func (as *stddevAggrState) pushSample(inputKey, outputKey string, value float64) {
+again:
+	v, ok := as.m.Load(outputKey)
+	if !ok {
+		// The entry is missing in the map. Try creating it.
+		v = &stddevStateValue{}
+		vNew, loaded := as.m.LoadOrStore(outputKey, v)
+		if loaded {
+			// Use the entry created by a concurrent goroutine.
+			v = vNew
+		}
+	}
+	sv := v.(*stddevStateValue)
+	sv.mu.Lock()
+	deleted := sv.deleted
+	if !deleted {
+		// See `Rapid calculation methods` at https://en.wikipedia.org/wiki/Standard_deviation
+		sv.count++
+		avg := sv.avg + (value-sv.avg)/sv.count
+		sv.q += (value - sv.avg) * (value - avg)
+		sv.avg = avg
+	}
+	sv.mu.Unlock()
+	if deleted {
+		// The entry has been deleted by the concurrent call to appendSeriesForFlush
+		// Try obtaining and updating the entry again.
+		goto again
+	}
+}
+
+func (as *stddevAggrState) appendSeriesForFlush(ctx *flushCtx) {
+	currentTimeMsec := int64(fasttime.UnixTimestamp()) * 1000
+	m := &as.m
+	m.Range(func(k, v interface{}) bool {
+		// Atomically delete the entry from the map, so new entry is created for the next flush.
+		m.Delete(k)
+
+		sv := v.(*stddevStateValue)
+		sv.mu.Lock()
+		stddev := math.Sqrt(sv.q / sv.count)
+		// Mark the entry as deleted, so it won't be updated anymore by concurrent pushSample() calls.
+		sv.deleted = true
+		sv.mu.Unlock()
+		key := k.(string)
+		ctx.appendSeries(key, "stddev", currentTimeMsec, stddev)
+		return true
+	})
+}
diff --git a/lib/streamaggr/stdvar.go b/lib/streamaggr/stdvar.go
new file mode 100644
index 000000000..d9a19e592
--- /dev/null
+++ b/lib/streamaggr/stdvar.go
@@ -0,0 +1,73 @@
+package streamaggr
+
+import (
+	"sync"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
+)
+
+// stdvarAggrState calculates output=stdvar, e.g. the average value over input samples.
+type stdvarAggrState struct {
+	m sync.Map
+}
+
+type stdvarStateValue struct {
+	mu      sync.Mutex
+	count   float64
+	avg     float64
+	q       float64
+	deleted bool
+}
+
+func newStdvarAggrState() *stdvarAggrState {
+	return &stdvarAggrState{}
+}
+
+func (as *stdvarAggrState) pushSample(inputKey, outputKey string, value float64) {
+again:
+	v, ok := as.m.Load(outputKey)
+	if !ok {
+		// The entry is missing in the map. Try creating it.
+		v = &stdvarStateValue{}
+		vNew, loaded := as.m.LoadOrStore(outputKey, v)
+		if loaded {
+			// Use the entry created by a concurrent goroutine.
+			v = vNew
+		}
+	}
+	sv := v.(*stdvarStateValue)
+	sv.mu.Lock()
+	deleted := sv.deleted
+	if !deleted {
+		// See `Rapid calculation methods` at https://en.wikipedia.org/wiki/Standard_deviation
+		sv.count++
+		avg := sv.avg + (value-sv.avg)/sv.count
+		sv.q += (value - sv.avg) * (value - avg)
+		sv.avg = avg
+	}
+	sv.mu.Unlock()
+	if deleted {
+		// The entry has been deleted by the concurrent call to appendSeriesForFlush
+		// Try obtaining and updating the entry again.
+		goto again
+	}
+}
+
+func (as *stdvarAggrState) appendSeriesForFlush(ctx *flushCtx) {
+	currentTimeMsec := int64(fasttime.UnixTimestamp()) * 1000
+	m := &as.m
+	m.Range(func(k, v interface{}) bool {
+		// Atomically delete the entry from the map, so new entry is created for the next flush.
+		m.Delete(k)
+
+		sv := v.(*stdvarStateValue)
+		sv.mu.Lock()
+		stdvar := sv.q / sv.count
+		// Mark the entry as deleted, so it won't be updated anymore by concurrent pushSample() calls.
+		sv.deleted = true
+		sv.mu.Unlock()
+		key := k.(string)
+		ctx.appendSeries(key, "stdvar", currentTimeMsec, stdvar)
+		return true
+	})
+}
diff --git a/lib/streamaggr/streamaggr.go b/lib/streamaggr/streamaggr.go
new file mode 100644
index 000000000..ff9bab6a6
--- /dev/null
+++ b/lib/streamaggr/streamaggr.go
@@ -0,0 +1,641 @@
+package streamaggr
+
+import (
+	"fmt"
+	"math"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/encoding"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fs"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promrelabel"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promutils"
+	"gopkg.in/yaml.v2"
+)
+
+var supportedOutputs = []string{
+	"total",
+	"increase",
+	"count_series",
+	"count_samples",
+	"sum_samples",
+	"last",
+	"min",
+	"max",
+	"avg",
+	"stddev",
+	"stdvar",
+	"histogram_bucket",
+	"quantiles(phi1, ..., phiN)",
+}
+
+// LoadFromFile loads Aggregators from the given path and uses the given pushFunc for pushing the aggregated data.
+//
+// The returned Aggregators must be stopped with MustStop() when no longer needed.
+func LoadFromFile(path string, pushFunc PushFunc) (*Aggregators, error) {
+	data, err := fs.ReadFileOrHTTP(path)
+	if err != nil {
+		return nil, fmt.Errorf("cannot load aggregators: %w", err)
+	}
+	as, err := NewAggregatorsFromData(data, pushFunc)
+	if err != nil {
+		return nil, fmt.Errorf("cannot initialize aggregators from %q: %w", path, err)
+	}
+	return as, nil
+}
+
+// NewAggregatorsFromData initializes Aggregators from the given data and uses the given pushFunc for pushing the aggregated data.
+//
+// The returned Aggregators must be stopped with MustStop() when no longer needed.
+func NewAggregatorsFromData(data []byte, pushFunc PushFunc) (*Aggregators, error) {
+	var cfgs []*Config
+	if err := yaml.UnmarshalStrict(data, &cfgs); err != nil {
+		return nil, err
+	}
+	return NewAggregators(cfgs, pushFunc)
+}
+
+// Config is a configuration for a single stream aggregation.
+type Config struct {
+	// Match is a label selector for filtering time series for the given selector.
+	//
+	// If the match isn't set, then all the input time series are processed.
+	Match *promrelabel.IfExpression `yaml:"match,omitempty"`
+
+	// Interval is the interval between aggregations.
+	Interval string `yaml:"interval"`
+
+	// Outputs is a list of output aggregate functions to produce.
+	//
+	// The following names are allowed:
+	//
+	// - total - aggregates input counters
+	// - increase - counts the increase over input counters
+	// - count_series - counts the input series
+	// - count_samples - counts the input samples
+	// - sum_samples - sums the input samples
+	// - last - the last biggest sample value
+	// - min - the minimum sample value
+	// - max - the maximum sample value
+	// - avg - the average value across all the samples
+	// - stddev - standard deviation across all the samples
+	// - stdvar - standard variance across all the samples
+	// - histogram_bucket - creates VictoriaMetrics histogram for input samples
+	// - quantiles(phi1, ..., phiN) - quantiles' estimation for phi in the range [0..1]
+	//
+	// The output time series will have the following names:
+	//
+	//   input_name:aggr_<interval>_<output>
+	//
+	Outputs []string `yaml:"outputs"`
+
+	// By is an optional list of labels for grouping input series.
+	//
+	// See also Without.
+	//
+	// If neither By nor Without are set, then the Outputs are calculated
+	// individually per each input time series.
+	By []string `yaml:"by,omitempty"`
+
+	// Without is an optional list of labels, which must be excluded when grouping input series.
+	//
+	// See also By.
+	//
+	// If neither By nor Without are set, then the Outputs are calculated
+	// individually per each input time series.
+	Without []string `yaml:"without,omitempty"`
+
+	// InputRelabelConfigs is an optional relabeling rules, which are applied on the input
+	// before aggregation.
+	InputRelabelConfigs []promrelabel.RelabelConfig `yaml:"input_relabel_configs,omitempty"`
+
+	// OutputRelabelConfigs is an optional relabeling rules, which are applied
+	// on the aggregated output before being sent to remote storage.
+	OutputRelabelConfigs []promrelabel.RelabelConfig `yaml:"output_relabel_configs,omitempty"`
+}
+
+// Aggregators aggregates metrics passed to Push and calls pushFunc for aggregate data.
+type Aggregators struct {
+	as []*aggregator
+}
+
+// NewAggregators creates Aggregators from the given cfgs.
+//
+// pushFunc is called when the aggregated data must be flushed.
+//
+// MustStop must be called on the returned Aggregators when they are no longer needed.
+func NewAggregators(cfgs []*Config, pushFunc PushFunc) (*Aggregators, error) {
+	if len(cfgs) == 0 {
+		return nil, nil
+	}
+	as := make([]*aggregator, len(cfgs))
+	for i, cfg := range cfgs {
+		a, err := newAggregator(cfg, pushFunc)
+		if err != nil {
+			return nil, fmt.Errorf("cannot initialize aggregator #%d: %w", i, err)
+		}
+		as[i] = a
+	}
+	return &Aggregators{
+		as: as,
+	}, nil
+}
+
+// MustStop stops a.
+func (a *Aggregators) MustStop() {
+	if a == nil {
+		return
+	}
+	for _, aggr := range a.as {
+		aggr.MustStop()
+	}
+}
+
+// Push pushes tss to a.
+func (a *Aggregators) Push(tss []prompbmarshal.TimeSeries) {
+	if a == nil {
+		return
+	}
+	for _, aggr := range a.as {
+		aggr.Push(tss)
+	}
+}
+
+// aggregator aggregates input series according to the config passed to NewAggregator
+type aggregator struct {
+	match *promrelabel.IfExpression
+
+	inputRelabeling  *promrelabel.ParsedConfigs
+	outputRelabeling *promrelabel.ParsedConfigs
+
+	by                  []string
+	without             []string
+	aggregateOnlyByTime bool
+
+	// aggrStates contains aggregate states for the given outputs
+	aggrStates []aggrState
+
+	pushFunc PushFunc
+
+	// suffix contains a suffix, which should be added to aggregate metric names
+	//
+	// It contains the interval, lables in (by, without), plus output name.
+	// For example, foo_bar metric name is transformed to foo_bar:1m_by_job
+	// for `interval: 1m`, `by: [job]`
+	suffix string
+
+	wg     sync.WaitGroup
+	stopCh chan struct{}
+}
+
+type aggrState interface {
+	pushSample(inputKey, outputKey string, value float64)
+	appendSeriesForFlush(ctx *flushCtx)
+}
+
+// PushFunc is called by Aggregators when it needs to push its state to metrics storage
+type PushFunc func(tss []prompbmarshal.TimeSeries)
+
+// newAggregator creates new aggregator for the given cfg, which pushes the aggregate data to pushFunc.
+//
+// The returned aggregator must be stopped when no longer needed by calling MustStop().
+func newAggregator(cfg *Config, pushFunc PushFunc) (*aggregator, error) {
+	// check cfg.Interval
+	interval, err := time.ParseDuration(cfg.Interval)
+	if err != nil {
+		return nil, fmt.Errorf("cannot parse `interval: %q`: %w", cfg.Interval, err)
+	}
+	if interval <= time.Second {
+		return nil, fmt.Errorf("the minimum supported aggregation interval is 1s; got %s", interval)
+	}
+
+	// initialize input_relabel_configs and output_relabel_configs
+	inputRelabeling, err := promrelabel.ParseRelabelConfigs(cfg.InputRelabelConfigs)
+	if err != nil {
+		return nil, fmt.Errorf("cannot parse input_relabel_configs: %w", err)
+	}
+	outputRelabeling, err := promrelabel.ParseRelabelConfigs(cfg.OutputRelabelConfigs)
+	if err != nil {
+		return nil, fmt.Errorf("cannot parse output_relabel_configs: %w", err)
+	}
+
+	// check by and without lists
+	by := cfg.By
+	without := cfg.Without
+	if len(by) > 0 && len(without) > 0 {
+		return nil, fmt.Errorf("`by: %s` and `without: %s` lists cannot be set simultaneously", by, without)
+	}
+	aggregateOnlyByTime := (len(by) == 0 && len(without) == 0)
+	if !aggregateOnlyByTime && len(without) == 0 {
+		by = addMissingUnderscoreName(by)
+	}
+
+	// initialize outputs list
+	if len(cfg.Outputs) == 0 {
+		return nil, fmt.Errorf("`outputs` list must contain at least a single entry from the list %s; "+
+			"see https://docs.victoriametrics.com/vmagent.html#stream-aggregation", supportedOutputs)
+	}
+	aggrStates := make([]aggrState, len(cfg.Outputs))
+	for i, output := range cfg.Outputs {
+		if strings.HasPrefix(output, "quantiles(") {
+			if !strings.HasSuffix(output, ")") {
+				return nil, fmt.Errorf("missing closing brace for `quantiles()` output")
+			}
+			argsStr := output[len("quantiles(") : len(output)-1]
+			if len(argsStr) == 0 {
+				return nil, fmt.Errorf("`quantiles()` must contain at least one phi")
+			}
+			args := strings.Split(argsStr, ",")
+			phis := make([]float64, len(args))
+			for j, arg := range args {
+				arg = strings.TrimSpace(arg)
+				phi, err := strconv.ParseFloat(arg, 64)
+				if err != nil {
+					return nil, fmt.Errorf("cannot parse phi=%q for quantiles(%s): %w", arg, argsStr, err)
+				}
+				if phi < 0 || phi > 1 {
+					return nil, fmt.Errorf("phi inside quantiles(%s) must be in the range [0..1]; got %v", argsStr, phi)
+				}
+				phis[j] = phi
+			}
+			aggrStates[i] = newQuantilesAggrState(phis)
+			continue
+		}
+		switch output {
+		case "total":
+			aggrStates[i] = newTotalAggrState(interval)
+		case "increase":
+			aggrStates[i] = newIncreaseAggrState(interval)
+		case "count_series":
+			aggrStates[i] = newCountSeriesAggrState()
+		case "count_samples":
+			aggrStates[i] = newCountSamplesAggrState()
+		case "sum_samples":
+			aggrStates[i] = newSumSamplesAggrState()
+		case "last":
+			aggrStates[i] = newLastAggrState()
+		case "min":
+			aggrStates[i] = newMinAggrState()
+		case "max":
+			aggrStates[i] = newMaxAggrState()
+		case "avg":
+			aggrStates[i] = newAvgAggrState()
+		case "stddev":
+			aggrStates[i] = newStddevAggrState()
+		case "stdvar":
+			aggrStates[i] = newStdvarAggrState()
+		case "histogram_bucket":
+			aggrStates[i] = newHistogramBucketAggrState(interval)
+		default:
+			return nil, fmt.Errorf("unsupported output=%q; supported values: %s; "+
+				"see https://docs.victoriametrics.com/vmagent.html#stream-aggregation", output, supportedOutputs)
+		}
+	}
+
+	// initialize suffix to add to metric names after aggregation
+	suffix := ":" + cfg.Interval
+	if labels := removeUnderscoreName(by); len(labels) > 0 {
+		suffix += fmt.Sprintf("_by_%s", strings.Join(labels, "_"))
+	}
+	if labels := removeUnderscoreName(without); len(labels) > 0 {
+		suffix += fmt.Sprintf("_without_%s", strings.Join(labels, "_"))
+	}
+	suffix += "_"
+
+	// initialize the aggregator
+	a := &aggregator{
+		match: cfg.Match,
+
+		inputRelabeling:  inputRelabeling,
+		outputRelabeling: outputRelabeling,
+
+		by:                  by,
+		without:             without,
+		aggregateOnlyByTime: aggregateOnlyByTime,
+
+		aggrStates: aggrStates,
+		pushFunc:   pushFunc,
+
+		suffix: suffix,
+
+		stopCh: make(chan struct{}),
+	}
+
+	a.wg.Add(1)
+	go func() {
+		a.runFlusher(interval)
+		defer a.wg.Done()
+	}()
+
+	return a, nil
+}
+
+func (a *aggregator) runFlusher(interval time.Duration) {
+	t := time.NewTicker(interval)
+	defer t.Stop()
+	for {
+		select {
+		case <-a.stopCh:
+			return
+		case <-t.C:
+		}
+		a.flush()
+	}
+}
+
+func (a *aggregator) flush() {
+	ctx := &flushCtx{
+		suffix: a.suffix,
+	}
+	for _, as := range a.aggrStates {
+		ctx.reset()
+		as.appendSeriesForFlush(ctx)
+
+		tss := ctx.tss
+
+		// Apply output relabeling
+		if a.outputRelabeling != nil {
+			dst := tss[:0]
+			for _, ts := range tss {
+				ts.Labels = a.outputRelabeling.Apply(ts.Labels, 0)
+				if len(ts.Labels) == 0 {
+					// The metric has been deleted by the relabeling
+					continue
+				}
+				dst = append(dst, ts)
+			}
+			tss = dst
+		}
+
+		// Push the output metrics
+		a.pushFunc(tss)
+	}
+}
+
+// MustStop stops the aggregator.
+//
+// The aggregator stops pushing the aggregated metrics after this call.
+func (a *aggregator) MustStop() {
+	close(a.stopCh)
+	a.wg.Wait()
+}
+
+// Push pushes series to a.
+func (a *aggregator) Push(tss []prompbmarshal.TimeSeries) {
+	labels := promutils.GetLabels()
+	tmpLabels := promutils.GetLabels()
+	bb := bbPool.Get()
+	for _, ts := range tss {
+		if !a.match.Match(ts.Labels) {
+			continue
+		}
+
+		labels.Labels = append(labels.Labels[:0], ts.Labels...)
+		labels.Labels = a.inputRelabeling.Apply(labels.Labels, 0)
+		if len(labels.Labels) == 0 {
+			// The metric has been deleted by the relabeling
+			continue
+		}
+		labels.Sort()
+
+		if a.aggregateOnlyByTime {
+			bb.B = marshalLabelsFast(bb.B[:0], labels.Labels)
+		} else {
+			tmpLabels.Labels = removeUnneededLabels(tmpLabels.Labels[:0], labels.Labels, a.by, a.without)
+			bb.B = marshalLabelsFast(bb.B[:0], tmpLabels.Labels)
+		}
+		outputKey := bytesutil.InternBytes(bb.B)
+		inputKey := ""
+		if !a.aggregateOnlyByTime {
+			tmpLabels.Labels = extractUnneededLabels(tmpLabels.Labels[:0], labels.Labels, a.by, a.without)
+			bb.B = marshalLabelsFast(bb.B[:0], tmpLabels.Labels)
+			inputKey = bytesutil.InternBytes(bb.B)
+		}
+
+		for _, sample := range ts.Samples {
+			a.pushSample(inputKey, outputKey, sample.Value)
+		}
+	}
+	bbPool.Put(bb)
+	promutils.PutLabels(tmpLabels)
+	promutils.PutLabels(labels)
+}
+
+var bbPool bytesutil.ByteBufferPool
+
+func (a *aggregator) pushSample(inputKey, outputKey string, value float64) {
+	if math.IsNaN(value) {
+		// Skip nan samples
+		return
+	}
+	for _, as := range a.aggrStates {
+		as.pushSample(inputKey, outputKey, value)
+	}
+}
+
+func extractUnneededLabels(dst, labels []prompbmarshal.Label, by, without []string) []prompbmarshal.Label {
+	if len(without) > 0 {
+		for _, label := range labels {
+			if hasInArray(label.Name, without) {
+				dst = append(dst, label)
+			}
+		}
+	} else {
+		for _, label := range labels {
+			if !hasInArray(label.Name, by) {
+				dst = append(dst, label)
+			}
+		}
+	}
+	return dst
+}
+
+func removeUnneededLabels(dst, labels []prompbmarshal.Label, by, without []string) []prompbmarshal.Label {
+	if len(without) > 0 {
+		for _, label := range labels {
+			if !hasInArray(label.Name, without) {
+				dst = append(dst, label)
+			}
+		}
+	} else {
+		for _, label := range labels {
+			if hasInArray(label.Name, by) {
+				dst = append(dst, label)
+			}
+		}
+	}
+	return dst
+}
+
+func hasInArray(name string, a []string) bool {
+	for _, s := range a {
+		if name == s {
+			return true
+		}
+	}
+	return false
+}
+
+func marshalLabelsFast(dst []byte, labels []prompbmarshal.Label) []byte {
+	dst = encoding.MarshalUint32(dst, uint32(len(labels)))
+	for _, label := range labels {
+		dst = encoding.MarshalUint32(dst, uint32(len(label.Name)))
+		dst = append(dst, label.Name...)
+		dst = encoding.MarshalUint32(dst, uint32(len(label.Value)))
+		dst = append(dst, label.Value...)
+	}
+	return dst
+}
+
+func unmarshalLabelsFast(dst []prompbmarshal.Label, src []byte) ([]prompbmarshal.Label, error) {
+	if len(src) < 4 {
+		return dst, fmt.Errorf("cannot unmarshal labels count from %d bytes; needs at least 4 bytes", len(src))
+	}
+	n := encoding.UnmarshalUint32(src)
+	src = src[4:]
+	for i := uint32(0); i < n; i++ {
+		// Unmarshal label name
+		if len(src) < 4 {
+			return dst, fmt.Errorf("cannot unmarshal label name length from %d bytes; needs at least 4 bytes", len(src))
+		}
+		labelNameLen := encoding.UnmarshalUint32(src)
+		src = src[4:]
+		if uint32(len(src)) < labelNameLen {
+			return dst, fmt.Errorf("cannot unmarshal label name from %d bytes; needs at least %d bytes", len(src), labelNameLen)
+		}
+		labelName := bytesutil.InternBytes(src[:labelNameLen])
+		src = src[labelNameLen:]
+
+		// Unmarshal label value
+		if len(src) < 4 {
+			return dst, fmt.Errorf("cannot unmarshal label value length from %d bytes; needs at least 4 bytes", len(src))
+		}
+		labelValueLen := encoding.UnmarshalUint32(src)
+		src = src[4:]
+		if uint32(len(src)) < labelValueLen {
+			return dst, fmt.Errorf("cannot unmarshal label value from %d bytes; needs at least %d bytes", len(src), labelValueLen)
+		}
+		labelValue := bytesutil.InternBytes(src[:labelValueLen])
+		src = src[labelValueLen:]
+
+		dst = append(dst, prompbmarshal.Label{
+			Name:  labelName,
+			Value: labelValue,
+		})
+	}
+	if len(src) > 0 {
+		return dst, fmt.Errorf("unexpected non-empty tail after unmarshaling labels; tail length is %d bytes", len(src))
+	}
+	return dst, nil
+}
+
+type flushCtx struct {
+	suffix string
+
+	tss     []prompbmarshal.TimeSeries
+	labels  []prompbmarshal.Label
+	samples []prompbmarshal.Sample
+}
+
+func (ctx *flushCtx) reset() {
+	ctx.tss = prompbmarshal.ResetTimeSeries(ctx.tss)
+	promrelabel.CleanLabels(ctx.labels)
+	ctx.labels = ctx.labels[:0]
+	ctx.samples = ctx.samples[:0]
+}
+
+func (ctx *flushCtx) appendSeries(labelsMarshaled, suffix string, timestamp int64, value float64) {
+	var err error
+	labelsLen := len(ctx.labels)
+	samplesLen := len(ctx.samples)
+	ctx.labels, err = unmarshalLabelsFast(ctx.labels, bytesutil.ToUnsafeBytes(labelsMarshaled))
+	if err != nil {
+		logger.Panicf("BUG: cannot unmarshal labels from output key: %s", err)
+	}
+	ctx.labels = addMetricSuffix(ctx.labels, labelsLen, ctx.suffix, suffix)
+	ctx.samples = append(ctx.samples, prompbmarshal.Sample{
+		Timestamp: timestamp,
+		Value:     value,
+	})
+	ctx.tss = append(ctx.tss, prompbmarshal.TimeSeries{
+		Labels:  ctx.labels[labelsLen:],
+		Samples: ctx.samples[samplesLen:],
+	})
+}
+
+func (ctx *flushCtx) appendSeriesWithExtraLabel(labelsMarshaled, suffix string, timestamp int64, value float64, extraName, extraValue string) {
+	var err error
+	labelsLen := len(ctx.labels)
+	samplesLen := len(ctx.samples)
+	ctx.labels, err = unmarshalLabelsFast(ctx.labels, bytesutil.ToUnsafeBytes(labelsMarshaled))
+	if err != nil {
+		logger.Panicf("BUG: cannot unmarshal labels from output key: %s", err)
+	}
+	ctx.labels = addMetricSuffix(ctx.labels, labelsLen, ctx.suffix, suffix)
+	ctx.labels = append(ctx.labels, prompbmarshal.Label{
+		Name:  extraName,
+		Value: extraValue,
+	})
+	ctx.samples = append(ctx.samples, prompbmarshal.Sample{
+		Timestamp: timestamp,
+		Value:     value,
+	})
+	ctx.tss = append(ctx.tss, prompbmarshal.TimeSeries{
+		Labels:  ctx.labels[labelsLen:],
+		Samples: ctx.samples[samplesLen:],
+	})
+}
+
+func addMetricSuffix(labels []prompbmarshal.Label, offset int, firstSuffix, lastSuffix string) []prompbmarshal.Label {
+	src := labels[offset:]
+	for i := range src {
+		label := &src[i]
+		if label.Name != "__name__" {
+			continue
+		}
+		bb := bbPool.Get()
+		bb.B = append(bb.B, label.Value...)
+		bb.B = append(bb.B, firstSuffix...)
+		bb.B = append(bb.B, lastSuffix...)
+		label.Value = bytesutil.InternBytes(bb.B)
+		bbPool.Put(bb)
+		return labels
+	}
+	// The __name__ isn't found. Add it
+	bb := bbPool.Get()
+	bb.B = append(bb.B, firstSuffix...)
+	bb.B = append(bb.B, lastSuffix...)
+	labelValue := bytesutil.InternBytes(bb.B)
+	labels = append(labels, prompbmarshal.Label{
+		Name:  "__name__",
+		Value: labelValue,
+	})
+	return labels
+}
+
+func addMissingUnderscoreName(labels []string) []string {
+	result := []string{"__name__"}
+	for _, s := range labels {
+		if s == "__name__" {
+			continue
+		}
+		result = append(result, s)
+	}
+	return result
+}
+
+func removeUnderscoreName(labels []string) []string {
+	var result []string
+	for _, s := range labels {
+		if s == "__name__" {
+			continue
+		}
+		result = append(result, s)
+	}
+	return result
+}
diff --git a/lib/streamaggr/streamaggr_test.go b/lib/streamaggr/streamaggr_test.go
new file mode 100644
index 000000000..bc2a11388
--- /dev/null
+++ b/lib/streamaggr/streamaggr_test.go
@@ -0,0 +1,662 @@
+package streamaggr
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+	"sync"
+	"testing"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promrelabel"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/prometheus"
+)
+
+func TestAggregatorsFailure(t *testing.T) {
+	f := func(config string) {
+		t.Helper()
+		pushFunc := func(tss []prompbmarshal.TimeSeries) {
+			panic(fmt.Errorf("pushFunc shouldn't be called"))
+		}
+		a, err := NewAggregatorsFromData([]byte(config), pushFunc)
+		if err == nil {
+			t.Fatalf("expecting non-nil error")
+		}
+		if a != nil {
+			t.Fatalf("expecting nil a")
+		}
+	}
+
+	// Invalid config
+	f(`foobar`)
+
+	// Unknown option
+	f(`
+- interval: 1m
+  outputs: [total]
+  foobar: baz
+`)
+
+	// missing interval
+	f(`
+- outputs: [total]
+`)
+
+	// missing outputs
+	f(`
+- interval: 1m
+`)
+
+	// Invalid output
+	f(`
+- interval: 1m
+  outputs: [foobar]
+`)
+
+	// Negative interval
+	f(`- interval: -5m`)
+	// Too small interval
+	f(`- interval: 10ms`)
+
+	// Invalid input_relabel_configs
+	f(`
+- interval: 1m
+  outputs: [total]
+  input_relabel_configs:
+  - foo: bar
+`)
+	f(`
+- interval: 1m
+  outputs: [total]
+  input_relabel_configs:
+  - action: replace
+`)
+
+	// Invalid output_relabel_configs
+	f(`
+- interval: 1m
+  outputs: [total]
+  output_relabel_configs:
+  - foo: bar
+`)
+	f(`
+- interval: 1m
+  outputs: [total]
+  output_relabel_configs:
+  - action: replace
+`)
+
+	// Both by and without are non-empty
+	f(`
+- interval: 1m
+  outputs: [total]
+  by: [foo]
+  without: [bar]
+`)
+
+	// Invalid quantiles()
+	f(`
+- interval: 1m
+  outputs: ["quantiles("]
+`)
+	f(`
+- interval: 1m
+  outputs: ["quantiles()"]
+`)
+	f(`
+- interval: 1m
+  outputs: ["quantiles(foo)"]
+`)
+	f(`
+- interval: 1m
+  outputs: ["quantiles(-0.5)"]
+`)
+	f(`
+- interval: 1m
+  outputs: ["quantiles(1.5)"]
+`)
+}
+
+func TestAggregatorsSuccess(t *testing.T) {
+	f := func(config, inputMetrics, outputMetricsExpected string) {
+		t.Helper()
+
+		// Initialize Aggregators
+		var tssOutput []prompbmarshal.TimeSeries
+		var tssOutputLock sync.Mutex
+		pushFunc := func(tss []prompbmarshal.TimeSeries) {
+			tssOutputLock.Lock()
+			for _, ts := range tss {
+				labelsCopy := append([]prompbmarshal.Label{}, ts.Labels...)
+				samplesCopy := append([]prompbmarshal.Sample{}, ts.Samples...)
+				tssOutput = append(tssOutput, prompbmarshal.TimeSeries{
+					Labels:  labelsCopy,
+					Samples: samplesCopy,
+				})
+			}
+			tssOutputLock.Unlock()
+		}
+		a, err := NewAggregatorsFromData([]byte(config), pushFunc)
+		if err != nil {
+			t.Fatalf("cannot initialize aggregators: %s", err)
+		}
+
+		// Push the inputMetrics to Aggregators
+		tssInput := mustParsePromMetrics(inputMetrics)
+		a.Push(tssInput)
+		if a != nil {
+			for _, aggr := range a.as {
+				aggr.flush()
+			}
+		}
+		a.MustStop()
+
+		// Verify the tssOutput contains the expected metrics
+		tsStrings := make([]string, len(tssOutput))
+		for i, ts := range tssOutput {
+			tsStrings[i] = timeSeriesToString(ts)
+		}
+		sort.Strings(tsStrings)
+		outputMetrics := strings.Join(tsStrings, "")
+		if outputMetrics != outputMetricsExpected {
+			t.Fatalf("unexpected output metrics;\ngot\n%s\nwant\n%s", outputMetrics, outputMetricsExpected)
+		}
+	}
+
+	// Empty config
+	f(``, ``, ``)
+	f(``, `foo{bar="baz"} 1`, ``)
+	f(``, "foo 1\nbaz 2", ``)
+
+	// Empty by list - aggregate only by time
+	f(`
+- interval: 1m
+  outputs: [count_samples, sum_samples, count_series, last]
+`, `
+foo{abc="123"} 4
+bar 5
+foo{abc="123"} 8.5
+foo{abc="456",de="fg"} 8
+`, `bar:1m_count_samples 1
+bar:1m_count_series 1
+bar:1m_last 5
+bar:1m_sum_samples 5
+foo:1m_count_samples{abc="123"} 2
+foo:1m_count_samples{abc="456",de="fg"} 1
+foo:1m_count_series{abc="123"} 1
+foo:1m_count_series{abc="456",de="fg"} 1
+foo:1m_last{abc="123"} 8.5
+foo:1m_last{abc="456",de="fg"} 8
+foo:1m_sum_samples{abc="123"} 12.5
+foo:1m_sum_samples{abc="456",de="fg"} 8
+`)
+
+	// Special case: __name__ in by list
+	f(`
+- interval: 1m
+  by: [__name__]
+  outputs: [count_samples, sum_samples, count_series]
+`, `
+foo{abc="123"} 4
+bar 5
+foo{abc="123"} 8.5
+foo{abc="456",de="fg"} 8
+`, `bar:1m_count_samples 1
+bar:1m_count_series 1
+bar:1m_sum_samples 5
+foo:1m_count_samples 3
+foo:1m_count_series 2
+foo:1m_sum_samples 20.5
+`)
+
+	// Non-empty by list with non-existing labels
+	f(`
+- interval: 1m
+  by: [foo, bar]
+  outputs: [count_samples, sum_samples, count_series]
+`, `
+foo{abc="123"} 4
+bar 5
+foo{abc="123"} 8.5
+foo{abc="456",de="fg"} 8
+`, `bar:1m_by_foo_bar_count_samples 1
+bar:1m_by_foo_bar_count_series 1
+bar:1m_by_foo_bar_sum_samples 5
+foo:1m_by_foo_bar_count_samples 3
+foo:1m_by_foo_bar_count_series 2
+foo:1m_by_foo_bar_sum_samples 20.5
+`)
+
+	// Non-empty by list with existing label
+	f(`
+- interval: 1m
+  by: [abc]
+  outputs: [count_samples, sum_samples, count_series]
+`, `
+foo{abc="123"} 4
+bar 5
+foo{abc="123"} 8.5
+foo{abc="456",de="fg"} 8
+`, `bar:1m_by_abc_count_samples 1
+bar:1m_by_abc_count_series 1
+bar:1m_by_abc_sum_samples 5
+foo:1m_by_abc_count_samples{abc="123"} 2
+foo:1m_by_abc_count_samples{abc="456"} 1
+foo:1m_by_abc_count_series{abc="123"} 1
+foo:1m_by_abc_count_series{abc="456"} 1
+foo:1m_by_abc_sum_samples{abc="123"} 12.5
+foo:1m_by_abc_sum_samples{abc="456"} 8
+`)
+
+	// Non-empty without list with non-existing labels
+	f(`
+- interval: 1m
+  without: [foo]
+  outputs: [count_samples, sum_samples, count_series]
+`, `
+foo{abc="123"} 4
+bar 5
+foo{abc="123"} 8.5
+foo{abc="456",de="fg"} 8
+`, `bar:1m_without_foo_count_samples 1
+bar:1m_without_foo_count_series 1
+bar:1m_without_foo_sum_samples 5
+foo:1m_without_foo_count_samples{abc="123"} 2
+foo:1m_without_foo_count_samples{abc="456",de="fg"} 1
+foo:1m_without_foo_count_series{abc="123"} 1
+foo:1m_without_foo_count_series{abc="456",de="fg"} 1
+foo:1m_without_foo_sum_samples{abc="123"} 12.5
+foo:1m_without_foo_sum_samples{abc="456",de="fg"} 8
+`)
+
+	// Non-empty without list with existing labels
+	f(`
+- interval: 1m
+  without: [abc]
+  outputs: [count_samples, sum_samples, count_series]
+`, `
+foo{abc="123"} 4
+bar 5
+foo{abc="123"} 8.5
+foo{abc="456",de="fg"} 8
+`, `bar:1m_without_abc_count_samples 1
+bar:1m_without_abc_count_series 1
+bar:1m_without_abc_sum_samples 5
+foo:1m_without_abc_count_samples 2
+foo:1m_without_abc_count_samples{de="fg"} 1
+foo:1m_without_abc_count_series 1
+foo:1m_without_abc_count_series{de="fg"} 1
+foo:1m_without_abc_sum_samples 12.5
+foo:1m_without_abc_sum_samples{de="fg"} 8
+`)
+
+	// Special case: __name__ in without list
+	f(`
+- interval: 1m
+  without: [__name__]
+  outputs: [count_samples, sum_samples, count_series]
+`, `
+foo{abc="123"} 4
+bar 5
+foo{abc="123"} 8.5
+foo{abc="456",de="fg"} 8
+`, `:1m_count_samples 1
+:1m_count_samples{abc="123"} 2
+:1m_count_samples{abc="456",de="fg"} 1
+:1m_count_series 1
+:1m_count_series{abc="123"} 1
+:1m_count_series{abc="456",de="fg"} 1
+:1m_sum_samples 5
+:1m_sum_samples{abc="123"} 12.5
+:1m_sum_samples{abc="456",de="fg"} 8
+`)
+
+	// drop some input metrics
+	f(`
+- interval: 1m
+  without: [abc]
+  outputs: [count_samples, sum_samples, count_series]
+  input_relabel_configs:
+  - if: 'foo'
+    action: drop
+`, `
+foo{abc="123"} 4
+bar 5
+foo{abc="123"} 8.5
+foo{abc="456",de="fg"} 8
+`, `bar:1m_without_abc_count_samples 1
+bar:1m_without_abc_count_series 1
+bar:1m_without_abc_sum_samples 5
+`)
+
+	// rename output metrics
+	f(`
+- interval: 1m
+  without: [abc]
+  outputs: [count_samples, sum_samples, count_series]
+  output_relabel_configs:
+  - action: replace_all
+    source_labels: [__name__]
+    regex: ":|_"
+    replacement: "-"
+    target_label: __name__
+  - action: drop
+    source_labels: [de]
+    regex: fg
+`, `
+foo{abc="123"} 4
+bar 5
+foo{abc="123"} 8.5
+foo{abc="456",de="fg"} 8
+`, `bar-1m-without-abc-count-samples 1
+bar-1m-without-abc-count-series 1
+bar-1m-without-abc-sum-samples 5
+foo-1m-without-abc-count-samples 2
+foo-1m-without-abc-count-series 1
+foo-1m-without-abc-sum-samples 12.5
+`)
+
+	// match doesn't match anything
+	f(`
+- interval: 1m
+  without: [abc]
+  outputs: [count_samples, sum_samples, count_series]
+  match: '{non_existing_label!=""}'
+`, `
+foo{abc="123"} 4
+bar 5
+foo{abc="123"} 8.5
+foo{abc="456",de="fg"} 8
+`, ``)
+
+	// match matches foo series with non-empty abc label
+	f(`
+- interval: 1m
+  by: [abc]
+  outputs: [count_samples, sum_samples, count_series]
+  match: 'foo{abc=~".+"}'
+`, `
+foo{abc="123"} 4
+bar 5
+foo{abc="123"} 8.5
+foo{abc="456",de="fg"} 8
+`, `foo:1m_by_abc_count_samples{abc="123"} 2
+foo:1m_by_abc_count_samples{abc="456"} 1
+foo:1m_by_abc_count_series{abc="123"} 1
+foo:1m_by_abc_count_series{abc="456"} 1
+foo:1m_by_abc_sum_samples{abc="123"} 12.5
+foo:1m_by_abc_sum_samples{abc="456"} 8
+`)
+
+	// total output for non-repeated series
+	f(`
+- interval: 1m
+  outputs: [total]
+`, `
+foo 123
+bar{baz="qwe"} 4.34
+`, `bar:1m_total{baz="qwe"} 0
+foo:1m_total 0
+`)
+
+	// total output for repeated series
+	f(`
+- interval: 1m
+  outputs: [total]
+`, `
+foo 123
+bar{baz="qwe"} 1.32
+bar{baz="qwe"} 4.34
+bar{baz="qwe"} 2
+foo{baz="qwe"} -5
+bar{baz="qwer"} 343
+bar{baz="qwer"} 344
+foo{baz="qwe"} 10
+`, `bar:1m_total{baz="qwe"} 5.02
+bar:1m_total{baz="qwer"} 1
+foo:1m_total 0
+foo:1m_total{baz="qwe"} 15
+`)
+
+	// total output for repeated series with group by __name__
+	f(`
+- interval: 1m
+  by: [__name__]
+  outputs: [total]
+`, `
+foo 123
+bar{baz="qwe"} 1.32
+bar{baz="qwe"} 4.34
+bar{baz="qwe"} 2
+foo{baz="qwe"} -5
+bar{baz="qwer"} 343
+bar{baz="qwer"} 344
+foo{baz="qwe"} 10
+`, `bar:1m_total 6.02
+foo:1m_total 15
+`)
+
+	// increase output for non-repeated series
+	f(`
+- interval: 1m
+  outputs: [increase]
+`, `
+foo 123
+bar{baz="qwe"} 4.34
+`, `bar:1m_increase{baz="qwe"} 0
+foo:1m_increase 0
+`)
+
+	// increase output for repeated series
+	f(`
+- interval: 1m
+  outputs: [increase]
+`, `
+foo 123
+bar{baz="qwe"} 1.32
+bar{baz="qwe"} 4.34
+bar{baz="qwe"} 2
+foo{baz="qwe"} -5
+bar{baz="qwer"} 343
+bar{baz="qwer"} 344
+foo{baz="qwe"} 10
+`, `bar:1m_increase{baz="qwe"} 5.02
+bar:1m_increase{baz="qwer"} 1
+foo:1m_increase 0
+foo:1m_increase{baz="qwe"} 15
+`)
+
+	// multiple aggregate configs
+	f(`
+- interval: 1m
+  outputs: [count_series, sum_samples]
+- interval: 5m
+  by: [bar]
+  outputs: [sum_samples]
+`, `
+foo 1
+foo{bar="baz"} 2
+foo 3.3
+`, `foo:1m_count_series 1
+foo:1m_count_series{bar="baz"} 1
+foo:1m_sum_samples 4.3
+foo:1m_sum_samples{bar="baz"} 2
+foo:5m_by_bar_sum_samples 4.3
+foo:5m_by_bar_sum_samples{bar="baz"} 2
+`)
+
+	// min and max outputs
+	f(`
+- interval: 1m
+  outputs: [min, max]
+`, `
+foo{abc="123"} 4
+bar 5
+foo{abc="123"} 8.5
+foo{abc="456",de="fg"} 8
+`, `bar:1m_max 5
+bar:1m_min 5
+foo:1m_max{abc="123"} 8.5
+foo:1m_max{abc="456",de="fg"} 8
+foo:1m_min{abc="123"} 4
+foo:1m_min{abc="456",de="fg"} 8
+`)
+
+	// avg output
+	f(`
+- interval: 1m
+  outputs: [avg]
+`, `
+foo{abc="123"} 4
+bar 5
+foo{abc="123"} 8.5
+foo{abc="456",de="fg"} 8
+`, `bar:1m_avg 5
+foo:1m_avg{abc="123"} 6.25
+foo:1m_avg{abc="456",de="fg"} 8
+`)
+
+	// stddev output
+	f(`
+- interval: 1m
+  outputs: [stddev]
+`, `
+foo{abc="123"} 4
+bar 5
+foo{abc="123"} 8.5
+foo{abc="456",de="fg"} 8
+`, `bar:1m_stddev 0
+foo:1m_stddev{abc="123"} 2.25
+foo:1m_stddev{abc="456",de="fg"} 0
+`)
+
+	// stdvar output
+	f(`
+- interval: 1m
+  outputs: [stdvar]
+`, `
+foo{abc="123"} 4
+bar 5
+foo{abc="123"} 8.5
+foo{abc="456",de="fg"} 8
+`, `bar:1m_stdvar 0
+foo:1m_stdvar{abc="123"} 5.0625
+foo:1m_stdvar{abc="456",de="fg"} 0
+`)
+
+	// histogram_bucket output
+	f(`
+- interval: 1m
+  outputs: [histogram_bucket]
+`, `
+cpu_usage{cpu="1"} 12.5
+cpu_usage{cpu="1"} 13.3
+cpu_usage{cpu="1"} 13
+cpu_usage{cpu="1"} 12
+cpu_usage{cpu="1"} 14
+cpu_usage{cpu="1"} 25
+cpu_usage{cpu="2"} 90
+`, `cpu_usage:1m_histogram_bucket{cpu="1",vmrange="1.136e+01...1.292e+01"} 2
+cpu_usage:1m_histogram_bucket{cpu="1",vmrange="1.292e+01...1.468e+01"} 3
+cpu_usage:1m_histogram_bucket{cpu="1",vmrange="2.448e+01...2.783e+01"} 1
+cpu_usage:1m_histogram_bucket{cpu="2",vmrange="8.799e+01...1.000e+02"} 1
+`)
+
+	// histogram_bucket output without cpu
+	f(`
+- interval: 1m
+  without: [cpu]
+  outputs: [histogram_bucket]
+`, `
+cpu_usage{cpu="1"} 12.5
+cpu_usage{cpu="1"} 13.3
+cpu_usage{cpu="1"} 13
+cpu_usage{cpu="1"} 12
+cpu_usage{cpu="1"} 14
+cpu_usage{cpu="1"} 25
+cpu_usage{cpu="2"} 90
+`, `cpu_usage:1m_without_cpu_histogram_bucket{vmrange="1.136e+01...1.292e+01"} 2
+cpu_usage:1m_without_cpu_histogram_bucket{vmrange="1.292e+01...1.468e+01"} 3
+cpu_usage:1m_without_cpu_histogram_bucket{vmrange="2.448e+01...2.783e+01"} 1
+cpu_usage:1m_without_cpu_histogram_bucket{vmrange="8.799e+01...1.000e+02"} 1
+`)
+
+	// quantiles output
+	f(`
+- interval: 1m
+  outputs: ["quantiles(0, 0.5, 1)"]
+`, `
+cpu_usage{cpu="1"} 12.5
+cpu_usage{cpu="1"} 13.3
+cpu_usage{cpu="1"} 13
+cpu_usage{cpu="1"} 12
+cpu_usage{cpu="1"} 14
+cpu_usage{cpu="1"} 25
+cpu_usage{cpu="2"} 90
+`, `cpu_usage:1m_quantiles{cpu="1",quantile="0"} 12
+cpu_usage:1m_quantiles{cpu="1",quantile="0.5"} 13.3
+cpu_usage:1m_quantiles{cpu="1",quantile="1"} 25
+cpu_usage:1m_quantiles{cpu="2",quantile="0"} 90
+cpu_usage:1m_quantiles{cpu="2",quantile="0.5"} 90
+cpu_usage:1m_quantiles{cpu="2",quantile="1"} 90
+`)
+
+	// quantiles output without cpu
+	f(`
+- interval: 1m
+  without: [cpu]
+  outputs: ["quantiles(0, 0.5, 1)"]
+`, `
+cpu_usage{cpu="1"} 12.5
+cpu_usage{cpu="1"} 13.3
+cpu_usage{cpu="1"} 13
+cpu_usage{cpu="1"} 12
+cpu_usage{cpu="1"} 14
+cpu_usage{cpu="1"} 25
+cpu_usage{cpu="2"} 90
+`, `cpu_usage:1m_without_cpu_quantiles{quantile="0"} 12
+cpu_usage:1m_without_cpu_quantiles{quantile="0.5"} 13.3
+cpu_usage:1m_without_cpu_quantiles{quantile="1"} 90
+`)
+}
+
+func timeSeriesToString(ts prompbmarshal.TimeSeries) string {
+	labelsString := promrelabel.LabelsToString(ts.Labels)
+	if len(ts.Samples) != 1 {
+		panic(fmt.Errorf("unexpected number of samples for %s: %d; want 1", labelsString, len(ts.Samples)))
+	}
+	return fmt.Sprintf("%s %v\n", labelsString, ts.Samples[0].Value)
+}
+
+func mustParsePromMetrics(s string) []prompbmarshal.TimeSeries {
+	var rows prometheus.Rows
+	errLogger := func(s string) {
+		panic(fmt.Errorf("unexpected error when parsing Prometheus metrics: %s", s))
+	}
+	rows.UnmarshalWithErrLogger(s, errLogger)
+	var tss []prompbmarshal.TimeSeries
+	samples := make([]prompbmarshal.Sample, 0, len(rows.Rows))
+	for _, row := range rows.Rows {
+		labels := make([]prompbmarshal.Label, 0, len(row.Tags)+1)
+		labels = append(labels, prompbmarshal.Label{
+			Name:  "__name__",
+			Value: row.Metric,
+		})
+		for _, tag := range row.Tags {
+			labels = append(labels, prompbmarshal.Label{
+				Name:  tag.Key,
+				Value: tag.Value,
+			})
+		}
+		samples = append(samples, prompbmarshal.Sample{
+			Value:     row.Value,
+			Timestamp: row.Timestamp,
+		})
+		ts := prompbmarshal.TimeSeries{
+			Labels:  labels,
+			Samples: samples[len(samples)-1:],
+		}
+		tss = append(tss, ts)
+	}
+	return tss
+}
diff --git a/lib/streamaggr/streamaggr_timing_test.go b/lib/streamaggr/streamaggr_timing_test.go
new file mode 100644
index 000000000..6ff151241
--- /dev/null
+++ b/lib/streamaggr/streamaggr_timing_test.go
@@ -0,0 +1,73 @@
+package streamaggr
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+)
+
+func BenchmarkAggregatorsPushByJobAvg(b *testing.B) {
+	for _, output := range []string{
+		"total",
+		"increase",
+		"count_series",
+		"count_samples",
+		"sum_samples",
+		"last",
+		"min",
+		"max",
+		"avg",
+		"stddev",
+		"stdvar",
+		"histogram_bucket",
+		"quantiles(0, 0.5, 1)",
+	} {
+		b.Run(fmt.Sprintf("output=%s", output), func(b *testing.B) {
+			benchmarkAggregatorsPush(b, output)
+		})
+	}
+}
+
+func benchmarkAggregatorsPush(b *testing.B, output string) {
+	config := fmt.Sprintf(`
+- match: http_requests_total
+  interval: 24h
+  without: [job]
+  outputs: [%q]
+`, output)
+	pushFunc := func(tss []prompbmarshal.TimeSeries) {
+		panic(fmt.Errorf("unexpected pushFunc call"))
+	}
+	a, err := NewAggregatorsFromData([]byte(config), pushFunc)
+	if err != nil {
+		b.Fatalf("unexpected error when initializing aggregators: %s", err)
+	}
+	defer a.MustStop()
+
+	b.ReportAllocs()
+	b.SetBytes(int64(len(benchSeries)))
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			a.Push(benchSeries)
+		}
+	})
+}
+
+func newBenchSeries(seriesCount, samplesPerSeries int) []prompbmarshal.TimeSeries {
+	a := make([]string, seriesCount*samplesPerSeries)
+	for i := 0; i < samplesPerSeries; i++ {
+		for j := 0; j < seriesCount; j++ {
+			s := fmt.Sprintf(`http_requests_total{path="/foo/%d",job="foo",instance="bar"} %d`, j, i*10)
+			a = append(a, s)
+		}
+	}
+	metrics := strings.Join(a, "\n")
+	return mustParsePromMetrics(metrics)
+}
+
+const seriesCount = 10000
+const samplesPerSeries = 10
+
+var benchSeries = newBenchSeries(seriesCount, samplesPerSeries)
diff --git a/lib/streamaggr/sum_samples.go b/lib/streamaggr/sum_samples.go
new file mode 100644
index 000000000..ba349a080
--- /dev/null
+++ b/lib/streamaggr/sum_samples.go
@@ -0,0 +1,71 @@
+package streamaggr
+
+import (
+	"sync"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
+)
+
+// sumSamplesAggrState calculates output=sum_samples, e.g. the sum over input samples.
+type sumSamplesAggrState struct {
+	m sync.Map
+}
+
+type sumSamplesStateValue struct {
+	mu      sync.Mutex
+	sum     float64
+	deleted bool
+}
+
+func newSumSamplesAggrState() *sumSamplesAggrState {
+	return &sumSamplesAggrState{}
+}
+
+func (as *sumSamplesAggrState) pushSample(inputKey, outputKey string, value float64) {
+again:
+	v, ok := as.m.Load(outputKey)
+	if !ok {
+		// The entry is missing in the map. Try creating it.
+		v = &sumSamplesStateValue{
+			sum: value,
+		}
+		vNew, loaded := as.m.LoadOrStore(outputKey, v)
+		if !loaded {
+			// The new entry has been successfully created.
+			return
+		}
+		// Use the entry created by a concurrent goroutine.
+		v = vNew
+	}
+	sv := v.(*sumSamplesStateValue)
+	sv.mu.Lock()
+	deleted := sv.deleted
+	if !deleted {
+		sv.sum += value
+	}
+	sv.mu.Unlock()
+	if deleted {
+		// The entry has been deleted by the concurrent call to appendSeriesForFlush
+		// Try obtaining and updating the entry again.
+		goto again
+	}
+}
+
+func (as *sumSamplesAggrState) appendSeriesForFlush(ctx *flushCtx) {
+	currentTimeMsec := int64(fasttime.UnixTimestamp()) * 1000
+	m := &as.m
+	m.Range(func(k, v interface{}) bool {
+		// Atomically delete the entry from the map, so new entry is created for the next flush.
+		m.Delete(k)
+
+		sv := v.(*sumSamplesStateValue)
+		sv.mu.Lock()
+		sum := sv.sum
+		// Mark the entry as deleted, so it won't be updated anymore by concurrent pushSample() calls.
+		sv.deleted = true
+		sv.mu.Unlock()
+		key := k.(string)
+		ctx.appendSeries(key, "sum_samples", currentTimeMsec, sum)
+		return true
+	})
+}
diff --git a/lib/streamaggr/total.go b/lib/streamaggr/total.go
new file mode 100644
index 000000000..b2e935acc
--- /dev/null
+++ b/lib/streamaggr/total.go
@@ -0,0 +1,137 @@
+package streamaggr
+
+import (
+	"math"
+	"sync"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
+)
+
+// totalAggrState calculates output=total, e.g. the summary counter over input counters.
+type totalAggrState struct {
+	m sync.Map
+
+	ignoreInputDeadline uint64
+	intervalSecs        uint64
+}
+
+type totalStateValue struct {
+	mu             sync.Mutex
+	lastValues     map[string]*lastValueState
+	total          float64
+	deleteDeadline uint64
+	deleted        bool
+}
+
+type lastValueState struct {
+	value          float64
+	deleteDeadline uint64
+}
+
+func newTotalAggrState(interval time.Duration) *totalAggrState {
+	currentTime := fasttime.UnixTimestamp()
+	intervalSecs := uint64(interval.Seconds() + 1)
+	return &totalAggrState{
+		ignoreInputDeadline: currentTime + intervalSecs,
+		intervalSecs:        intervalSecs,
+	}
+}
+
+func (as *totalAggrState) pushSample(inputKey, outputKey string, value float64) {
+	currentTime := fasttime.UnixTimestamp()
+	deleteDeadline := currentTime + as.intervalSecs + (as.intervalSecs >> 1)
+
+again:
+	v, ok := as.m.Load(outputKey)
+	if !ok {
+		// The entry is missing in the map. Try creating it.
+		v = &totalStateValue{
+			lastValues: make(map[string]*lastValueState),
+		}
+		vNew, loaded := as.m.LoadOrStore(outputKey, v)
+		if loaded {
+			// Use the entry created by a concurrent goroutine.
+			v = vNew
+		}
+	}
+	sv := v.(*totalStateValue)
+	sv.mu.Lock()
+	deleted := sv.deleted
+	if !deleted {
+		lv, ok := sv.lastValues[inputKey]
+		if !ok {
+			lv = &lastValueState{}
+			sv.lastValues[inputKey] = lv
+		}
+		d := value
+		if ok && lv.value <= value {
+			d = value - lv.value
+		}
+		if ok || currentTime > as.ignoreInputDeadline {
+			sv.total += d
+		}
+		lv.value = value
+		lv.deleteDeadline = deleteDeadline
+		sv.deleteDeadline = deleteDeadline
+	}
+	sv.mu.Unlock()
+	if deleted {
+		// The entry has been deleted by the concurrent call to appendSeriesForFlush
+		// Try obtaining and updating the entry again.
+		goto again
+	}
+}
+
+func (as *totalAggrState) removeOldEntries(currentTime uint64) {
+	m := &as.m
+	m.Range(func(k, v interface{}) bool {
+		sv := v.(*totalStateValue)
+
+		sv.mu.Lock()
+		deleted := currentTime > sv.deleteDeadline
+		if deleted {
+			// Mark the current entry as deleted
+			sv.deleted = deleted
+		} else {
+			// Delete outdated entries in sv.lastValues
+			m := sv.lastValues
+			for k1, v1 := range m {
+				if currentTime > v1.deleteDeadline {
+					delete(m, k1)
+				}
+			}
+		}
+		sv.mu.Unlock()
+
+		if deleted {
+			m.Delete(k)
+		}
+		return true
+	})
+}
+
+func (as *totalAggrState) appendSeriesForFlush(ctx *flushCtx) {
+	currentTime := fasttime.UnixTimestamp()
+	currentTimeMsec := int64(currentTime) * 1000
+
+	as.removeOldEntries(currentTime)
+
+	m := &as.m
+	m.Range(func(k, v interface{}) bool {
+		sv := v.(*totalStateValue)
+		sv.mu.Lock()
+		total := sv.total
+		if math.Abs(sv.total) >= (1 << 53) {
+			// It is time to reset the entry, since it starts losing float64 precision
+			sv.total = 0
+		}
+		deleted := sv.deleted
+		sv.mu.Unlock()
+		if !deleted {
+			key := k.(string)
+			ctx.appendSeries(key, "total", currentTimeMsec, total)
+		}
+		return true
+	})
+}