This allows removing importing unneeded command-line flags into binaries, which import lib/storage,
which, in turn, was importing lib/snapshot in order to use Time, Validate and NewName functions.
This is a follow-up for 83e55456e2
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5738
changes(), increases_over_time() and resets() shouldn't take into account
value changes, which may occur because of precision errors.
The maximum guaranteed precision for raw samples stored in VictoriaMetrics is 12 decimal digits.
So do not count relative changes for values if they are smaller than 1e-12 comparing to the value.
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/767
* vmui: fix select closing on click outside (#5728)
* vmui: clear entered text in select after selecting a value (#5727)
---------
Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
GOGC can be already set via environment variable. There is no need in adding
new approaches for setting the GOGC (such as command-line flag), since they complicate operations.
Remove temporary file before closing it in order to signal the OS that it shouldn't
store the file contents from page cache to disk when the file is closed.
Gracefully handle the case when the file cannot be removed before being closed -
in this case remove the file after closing it. This allows working on Windows.
Also remove superflouos opening of temporary file for reading - re-use already opened file handle for writing.
This is a follow-up for 9b1e002287
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/pull/4020
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/70
This case is possible after a new brsPool is allocated. The fix is to verify whether len(brsPool) >= len(brs.brs)
before trying to append a new item to brsPool and sharing its contents with brs.brs.
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5733
* app/vmselect: set proper timestamp for cached instant responses
The change updates `getSumInstantValues` to prefer timestamp
from the most recent results. Before, timestamp from cached series
was used.
The old behavior had negative impact on recording rules as they
were getting responses with shifted timestamps in past.
Subsequent recording or alerting rules fetching results of these
recording rules could get no result due to staleness interval.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5659
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* wip
---------
Signed-off-by: hagen1778 <roman@victoriametrics.com>
Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
There is no sense in running more than GOMAXPROCS concurrent marshalers,
since they are CPU-bound. More concurrent marshalers do not increase the marshaling bandwidth,
but they may result in more RAM usage.
This limit has little sense for these APIs, since:
- Thses APIs frequently result in scanning of all the time series on the given time range.
For example, if extra_filters={datacenter="some_dc"} .
- Users expect these APIs shouldn't hit the -search.maxUniqueTimeseries limit,
which is intended for limiting resource usage at /api/v1/query and /api/v1/query_range requests.
Also limit the concurrency for /api/v1/labels, /api/v1/label/.../values
and /api/v1/series requests in order to limit the maximum memory usage and CPU usage for these API.
This limit shouldn't affect typical use cases for these APIs:
- Grafana dashboard load when dashboard labels should be loaded
- Auto-suggestion list load when editing the query in Grafana or vmui
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5055
* app/vmalert: fix data race during hot-config reload
During hot-reload, the logic evokes the group update and rules evaluation
interruption simultaneously. Falsely assuming that interruption happens before
the update. However, it could happen that group will be updated first and only
after the rules evaluation will be cancelled. Which will result in permanent
interruption for all rules within the group.
The fix caches the cancel context function into local variable first. And only after
performs the group update. With cached cancel function we can safely call it without
worrying that we cancel the evaluation for already updated group.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* Revert "app/vmalert: fix data race during hot-config reload"
This reverts commit a4bb7e8932.
* app/vmalert: fix data race during hot-config reload
During hot-reload, the logic evokes the group update and rules evaluation
interruption simultaneously. Falsely assuming that interruption happens before
the update. However, it could happen that group will be updated first and only
after the rules evaluation will be cancelled. Which will result in permanent
interruption for all rules within the group.
The fix cancels the evaulation context before applying the update, making sure
that the context will be cancelled for old group always.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* wip
Signed-off-by: hagen1778 <roman@victoriametrics.com>
---------
Signed-off-by: hagen1778 <roman@victoriametrics.com>
- Maintain a separate worker pool per each part type (in-memory, file, big and small).
Previously a shared pool was used for merging all the part types.
A single merge worker could merge parts with mixed types at once. For example,
it could merge simultaneously an in-memory part plus a big file part.
Such a merge could take hours for big file part. During the duration of this merge
the in-memory part was pinned in memory and couldn't be persisted to disk
under the configured -inmemoryDataFlushInterval .
Another common issue, which could happen when parts with mixed types are merged,
is uncontrolled growth of in-memory parts or small parts when all the merge workers
were busy with merging big files. Such growth could lead to significant performance
degradataion for queries, since every query needs to check ever growing list of parts.
This could also slow down the registration of new time series, since VictoriaMetrics
searches for the internal series_id in the indexdb for every new time series.
The third issue is graceful shutdown duration, which could be very long when a background
merge is running on in-memory parts plus big file parts. This merge couldn't be interrupted,
since it merges in-memory parts.
A separate pool of merge workers per every part type elegantly resolves both issues:
- In-memory parts are merged to file-based parts in a timely manner, since the maximum
size of in-memory parts is limited.
- Long-running merges for big parts do not block merges for in-memory parts and small parts.
- Graceful shutdown duration is now limited by the time needed for flushing in-memory parts to files.
Merging for file parts is instantly canceled on graceful shutdown now.
- Deprecate -smallMergeConcurrency command-line flag, since the new background merge algorithm
should automatically self-tune according to the number of available CPU cores.
- Deprecate -finalMergeDelay command-line flag, since it wasn't working correctly.
It is better to run forced merge when needed - https://docs.victoriametrics.com/#forced-merge
- Tune the number of shards for pending rows and items before the data goes to in-memory parts
and becomes visible for search. This improves the maximum data ingestion rate and the maximum rate
for registration of new time series. This should reduce the duration of data ingestion slowdown
in VictoriaMetrics cluster on e.g. re-routing events, when some of vmstorage nodes become temporarily
unavailable.
- Prevent from possible "sync: WaitGroup misuse" panic on graceful shutdown.
This is a follow-up for fa566c68a6 .
Thanks @misutoth to for the inspiration at https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5212
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5190
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3790
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3551
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3337
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3425
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3647
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3641
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/648
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/291
* app/vmalert: autogenerate `ALERTS_FOR_STATE` time series for alerting rules with `for: 0`
Previously, `ALERTS_FOR_STATE` was generated only for alerts with `for > 0`.
This behavior differs from Prometheus behavior - it generates ALERTS_FOR_STATE
time series for alerting rules with `for: 0` as well. Such time series can
be useful for tracking the moment when alerting rule became active.
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5648https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3056
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* app/vmalert: support ALERTS_FOR_STATE in `replay` mode
Signed-off-by: hagen1778 <roman@victoriametrics.com>
---------
Signed-off-by: hagen1778 <roman@victoriametrics.com>
The maxFileParts usage has been accidentally removed in fa566c68a6
While at it, add Count suffix to *AssistedMerges counter names in order to make them less misleading.
Previously their names were falsely suggesting that these are gauges, which show the number of concurrently
executed assisted merges.
* vmui: fix the logic of closing the popper #5470
* vmui: fix the logic of caching autocomplete results #5472
---------
Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
This reduces the number of memory allocations at the cost of possible memory usage increase,
since now different metric name strings may hold references to the previous byte slice.
This is good tradeoff, since ProcessSearchQuery is called in vmselect, and vmselect isn't usually limited by memory.
This change has been extracted from https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5527
This should smooth CPU and RAM usage spikes related to these periodic tasks,
by reducing the probability that multiple concurrent periodic tasks are performed at the same time.
The change removes artificial delay before returning error, which sometimes
caused less retry events than expected.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
Examples:
1) -metricsAuthKey=file:///abs/path/to/file - reads flag value from the given absolute filepath
2) -metricsAuthKey=file://./relative/path/to/file - reads flag value from the given relative filepath
3) -metricsAuthKey=http://some-host/some/path?query_arg=abc - reads flag value from the given url
The flag value is automatically updated when the file contents changes.
* app/vmauth: adds metric_labels and backend_errors counter
it must improve observability for user requests with new metric - per user backend errors counter.
it's needed to calculate requests fail rate to the configured backends.
metric_labels configuration allows to perform additional aggregations on top of multiple users from configuration section.
It could be multiple clients or clients with separate read/write tokens
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5565
* wip
---------
Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
* app/vmselect/promql: properly handle possible negative results caused by float operations precision error in rollup functions like rate() or increase()
* fix test
Properly determine time range search for instant queries with too big look-behind window like `foo[100y]`.
Previously, such queries could return empty responses even if `foo` is present in database.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5553
Signed-off-by: hagen1778 <roman@victoriametrics.com>
app/victoriametrics: update the test suite
* simplify /query and /query_range test cases configuration and tests
* support instant queries with lookbehind window like `query=foo[5m]`
* support instant queries selecting scalar value like `query=42`
* add query_range test for prometheus
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* vmui/vmanomaly: add support models that produce only `anomaly_score`
* vmui/vmanomaly: fix display legend
* vmui/vmanomaly: update comment on anomaly threshold
It was calculating the number of dropped time series instead of the number of dropped samples.
While at it, drop vmalert_remotewrite_dropped_bytes_total metric, since it was inconsistently calculated -
at one place it was calculating raw protobuf-encoded sample sizes, while at another place it was calculating
the size of snappy-compressed prompbmarshal.WriteRequest protobuf message.
Additionally, this metric has zero practical sense, so just drop it in order to reduce the level of confusion.
automatically add `exported_` prefix for original evaluation result label if it's conflicted with external or reserved one,
previously it was overridden.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5161
Signed-off-by: hagen1778 <roman@victoriametrics.com>
Co-authored-by: hagen1778 <roman@victoriametrics.com>
* app/vmselect: drop `rollupDefault` function as duplicate
It is unclear why there are two identical fns `rollupDefault`
and `rollupDistinct`. Dropping one of them.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* Update app/vmselect/promql/rollup.go
* Update app/vmselect/promql/rollup.go
---------
Signed-off-by: hagen1778 <roman@victoriametrics.com>
Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
The user may which to control the endpoint parameters for instance to
set the audience when requesting an access token. Exposing the
parameters as a map allows for additional use cases without requiring
modification.
Before, retries happened only on writes into a network connection
between source and destination. But errors returned by server after
all the data was transmitted were logged, but not retried.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
app/vmselect/promql/eval.go:evalAggrFunc shunts evaluation
of AggrFuncExpr over rollupFunc over MetricsExpr to an optimized
path. tryGetArgRollupFuncWithMetricExpr() checks whether expression
can be shunted, but it mangles the AggrFuncExpr when the aggregation
function has more than one argument. This results in queries like
`sum(aggr_over_time("avg_over_time",m))` failing with error message
'expecting at least 2 args to "aggr_over_time"; got 1 args' while
the analogous query `sum(avg_over_time(m))` executes successfully.
This fix removes the unnecessary mangling.
Signed-off-by: Anton Tykhyy <atykhyy@gmail.com>
Previously `retry_status_codes: []` and `drop_src_path_prefix_parts: 0` at `url_map` were equivalent to missing values.
This was resulting in using the user-level values instead.
* vmui: add show quick tip for autocomplete
* vmui: auto-completion usability improvements #5348
* vmui: add const for min symbols in autocomplete
* Use proper queries to VictoriaMetrics
* vmui: fix comments for autocomplete
* app/vmselect: run `make vmui-update`
---------
Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
Before, vmalert would send notifications with labels containing characters
not supported by Alertmanager validator, resulting into validation errors
like `msg="Failed to validate alerts" err="invalid label set: invalid name "foo.bar"`
Signed-off-by: hagen1778 <roman@victoriametrics.com>
Previously the lower bound could be too small, which could result in missing values at the beginning of the graph
for default_rollup() function. This function is automatically applied to all the series selectors if they aren't
explicitly wrapped into a rollup function - see https://docs.victoriametrics.com/MetricsQL.html#implicit-query-conversions
While at it, properly take into account `-search.minStalenessInterval` command-line flag when adjusting
the lower bound for the selected time range.
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5388
- Add links to relevant docs into descriptions for every -kafka.* and -gcp.pubsub.* command-line flags.
- Wait until message processing goroutines are stopped before returning from gcppubsub.Stop().
- Prevent from multiple calls to Init() without Stop().
- Drop message if tenantID cannot be parsed properly.
- Take into account tenantID for all the supported message formats.
- Support gzip-compressed messages for graphite format.
- Use exponential backoff sleep when the message cannot be pushed to remote storage systems
because of disabled on-disk persistence - https://docs.victoriametrics.com/vmagent.html#disabling-on-disk-persistence
- Unblock from sleep as soon as Stop() is called. Previously the sleep could take up to 2 seconds after Stop() is called.
- Remove unused globalCtx and initContext from app/vmagent/remotewrite/gcppubsub
- Mention Google PubSub support at docs/enterprise.md
- Make Google PubSub docs more clear at docs/vmagent.md
This is a follow-up for commits 115245924a5f096c5a3383d6cc8e8b6fbd421984
and e6eab781ce42285a6a1750dc01eba6801dd35516 .
Updates https://github.com/VictoriaMetrics/VictoriaMetrics-enterprise/pull/717
Updates https://github.com/VictoriaMetrics/VictoriaMetrics-enterprise/pull/713
* app/vmalert: expose `/vmalert/api/v1/rule` and `/api/v1/rule` API which returns rule status in JSON format
* app/vmalert: hide updates if query param not set
* app/vmalert: fix panic (recursion call)
* app/vmalert: add needed group name and file name
* app/vmalert: fix comment, update behavior
* app/vmalert: fix description
* app/vmalert: simplify API for /api/v1/rule
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* app/vmalert: simplify API for /api/v1/rule
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* app/vmalert: simplify API for /api/v1/rule
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* app/vmalert: simplify API for /api/v1/rule
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* app/vmalert: simplify API for /api/v1/rule
Signed-off-by: hagen1778 <roman@victoriametrics.com>
---------
Signed-off-by: hagen1778 <roman@victoriametrics.com>
Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
Co-authored-by: hagen1778 <roman@victoriametrics.com>
Previously concurrency for static and fast queries was limited with the -search.maxConcurrentRequests
command-line flag. This could complicate identifying heavy queries via `vmui` at `Top queries` and `Active queries` pages,
since `vmui` and these pages couldn't be opened on overloaded vmselect.
Thanks to @f41gh7 for the idea.
* prevent /api/v1 from panic on parsing rows
* add tests for Extract function for v1 and v2 api's
* separate request types in different pools to prevent different objects mixing
* add changelog line
543f218fe9
Signed-off-by: hagen1778 <roman@victoriametrics.com>
Co-authored-by: Andrew Chubatiuk <andrew.chubatiuk@motional.com>
Co-authored-by: Nikolay <https://github.com/f41gh7>
Co-authored-by: Roman Khavronenko <roman@victoriametrics.com>
- Add Try* prefix to functions, which return bool result in order to improve readability and reduce the probability of missing check
for the result returned from these functions.
- Call the adjustSampleValues() only once on input samples. Previously it was called on every attempt to flush data to peristent queue.
- Properly restore the initial state of WriteRequest passed to tryPushWriteRequest() before returning from this function
after unsuccessful push to persistent queue. Previously a part of WriteRequest samples may be lost in such case.
- Add -remoteWrite.dropSamplesOnOverload command-line flag, which can be used for dropping incoming samples instead
of returning 429 Too Many Requests error to the client when -remoteWrite.disableOnDiskQueue is set and the remote storage
cannot keep up with the data ingestion rate.
- Add vmagent_remotewrite_samples_dropped_total metric, which counts the number of dropped samples.
- Add vmagent_remotewrite_push_failures_total metric, which counts the number of unsuccessful attempts to push
data to persistent queue when -remoteWrite.disableOnDiskQueue is set.
- Remove vmagent_remotewrite_aggregation_metrics_dropped_total and vm_promscrape_push_samples_dropped_total metrics,
because they are replaced with vmagent_remotewrite_samples_dropped_total metric.
- Update 'Disabling on-disk persistence' docs at docs/vmagent.md
- Update stale comments in the code
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5088
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/2110
* app/vmagent: allow to disabled on-disk queue
Previously, it wasn't possible to build data processing pipeline with a
chain of vmagents. In case when remoteWrite for the last vmagent in the
chain wasn't accessible, it persisted data only when it has enough disk
capacity. If disk queue is full, it started to silently drop ingested
metrics.
New flags allows to disable on-disk persistent and immediatly return an
error if remoteWrite is not accessible anymore. It blocks any writes and
notify client, that data ingestion isn't possible.
Main use case for this feature - use external queue such as kafka for
data persistence.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/2110
* adds test, updates readme
* apply review suggestions
* update docs for vmagent
* makes linter happy
---------
Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
Tests showed that importing a single line with 70MB size takes 5.3GiB
RSS memory for VictoriaMetrics single-node.
In the scenario when user exports and imports data from one VM to another,
it could possibly lead to OOM exception for destination VM.
Importing a single line with 16MB size taks 1.3GiB RSS memory.
Hence, the limit for `import.maxLineLen` was decreased from 100MB to 10MB
to improve reliability of VictoriaMetrics during imports.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
Previously the number of memory allocations inside copyTimeseriesShallow() was equal to 1+len(tss)
Reduce this number to 2 by pre-allocating a slice of timeseries structs with len(tss) length.
evalRollupFuncNoCache() may return time series with identical labels (aka duplicate series)
when performing queries satisfying all the following conditions:
- It must select time series with multiple metric names. For example, {__name__=~"foo|bar"}
- The series selector must be wrapped into rollup function, which drops metric names. For example, rate({__name__=~"foo|bar"})
- The rollup function must be wrapped into aggregate function, which has no streaming optimization.
For example, quantile(0.9, rate({__name__=~"foo|bar"})
In this case VictoriaMetrics shouldn't return `cannot merge series: duplicate series found` error.
Instead, it should fall back to query execution with disabled cache.
Also properly store the merged results. Previously they were incorrectly stored because of a typo
introduced in the commit 41a0fdaf39
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5332
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5337
- If min_over_time(m[offset] @ timestamp) <= min_over_time(m[offset] @ (timestamp-window)),
then the optimization can be applied.
- If max_over_time(m[offset] @ timestamp) >= max_over_time(m[offset] @ (timestamp-window)),
then the optimization can be applied.
* vmui: reduced the number of server requests
* run `make vmui-update vmui-logs-update`
---------
Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
Previously the `Host` header was remained unchanged when passing it in requests to backends.
This may improperly work if the backend uses host-based routing.
While at it, allows http/2.0 requests to backends. While VictoriaMetrics components
do not accept http/2.0 requests, other backends can require such requests.
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5240
- Re-use identically configured http.Transport across multiple users.
This fixes handling of the limit on the number of connection, which can be established per each backend
via -maxIdleConnsPerBackend command-line flag. This limit stopped working after 323f3720ed
- Add docs about backend TLS setup at https://docs.victoriametrics.com/vmauth.html#backend-tls-setup
- Add ability to disable backend TLS verification for all the users via -backend.tlsInsecureSkipVerify command-line flag.
This flag may be useful when -auth.config contains big number of users, and every user must disable backend TLS verification.
- Add ability to specify TLS Root CA via tls_ca_file option at per-user basis and via -backend.tlsCAFile command-line flag
across all the users.
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5240
* app/vmalert: update remote-write process
* automatically retry remote-write requests on closed connections. The change should reduce the amount of logs produced in environments with short-living connections or environments without support of keep-alive on network balancers.
* increment `vmalert_remotewrite_errors_total` metric if all retries to send remote-write request failed. Before, this metric was incremented only if remote-write client's buffer is overloaded.
* increment `vmalert_remotewrite_dropped_rows_total` amd `vmalert_remotewrite_dropped_bytes_total` metrics if remote-write client's buffer is overloaded. Before, these metrics were incremented only after unsuccessful HTTP calls.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* Update docs/CHANGELOG.md
---------
Signed-off-by: hagen1778 <roman@victoriametrics.com>
Co-authored-by: Hui Wang <haley@victoriametrics.com>
Add `tls_insecure_skip_verify` option on per-user basis which allows to disable TLS verification for all requests to backend on behalf of this user.
See: https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5240
Signed-off-by: Zakhar Bessarab <z.bessarab@victoriametrics.com>
reduce the number of queries for restoring alerts state on start-up.
The change should speed up the restore process and reduce pressure on `remoteRead.url`.
* vmauth: add browser authorization request for http requests without credentials to a route that is not in the `unauthorized_user` section (when `unauthorized_user` is specified).
* add link to issue in CHANGELOG
* Extend vmauth docs
* wip
---------
Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
This reduction is based on production testing.
Also expose -search.minWindowForInstantRollupOptimization command-line flag, so users could fine-tune this arg for their needs
vmalert expects string value for stats.seriesFetched, so it is impossible
switching to number without breaking compatibility with old vmalert releases :(
It is still unclear why stats.seriesFetched has string type in the first place...
Repeated instant queries with long lookbehind windows, which contain one of the following rollup functions,
are optimized via partial result caching:
- sum_over_time()
- count_over_time()
- avg_over_time()
- increase()
- rate()
The basic idea of optimization is to calculate
rf(m[d] @ t)
as
rf(m[offset] @ t) + rf(m[d] @ (t-offset)) - rf(m[offset] @ (t-d))
where rf(m[d] @ (t-offset)) is cached query result, which was calculated previously
The offset may be in the range of up to 1 hour.
