lib/storage: properly handle {__name__=~"prefix(suffix1|suffix2)",other_label="..."} queries

They were broken in the commit 00cbb099b6

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1644

docs/CHANGELOG.md

@@ -9,6 +9,7 @@ sort: 15
 * FEATURE: vmagent: add `vm_promscrape_max_scrape_size_exceeded_errors_total` metric for counting of the failed scrapes due to the exceeded response size (the response size limit can be configured via `-promscrape.maxScrapeSize` command-line flag). See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1639).
 
 * BUGFIX: vmalert: properly reload rule groups if only the `interval` config option is changed. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1641).
+* BUGFIX: properly handle `{__name__=~"prefix(suffix1|suffix2)",other_label="..."}` queries. They may return unexpected empty responses since v1.66.0. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1644).
 
 
 ## [v1.66.1](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.66.1)

lib/storage/tag_filters.go

@@ -29,6 +29,7 @@ func convertToCompositeTagFilters(tfs *TagFilters) []*TagFilters {
 	var tfssCompiled []*TagFilters
 	// Search for filters on metric name, which will be used for creating composite filters.
 	var names [][]byte
+	namePrefix := ""
 	hasPositiveFilter := false
 	for _, tf := range tfs.tfs {
 		if len(tf.key) == 0 {
@@ -42,6 +43,7 @@ func convertToCompositeTagFilters(tfs *TagFilters) []*TagFilters {
 				for _, orSuffix := range tf.orSuffixes {
 					names = append(names, []byte(orSuffix))
 				}
+				namePrefix = tf.regexpPrefix
 			}
 		} else if !tf.isNegative && !tf.isEmptyMatch {
 			hasPositiveFilter = true
@@ -53,7 +55,7 @@ func convertToCompositeTagFilters(tfs *TagFilters) []*TagFilters {
 	}
 
 	// Create composite filters for the found names.
-	var compositeKey []byte
+	var compositeKey, nameWithPrefix []byte
 	for _, name := range names {
 		compositeFilters := 0
 		tfsNew := make([]tagFilter, 0, len(tfs.tfs))
@@ -94,7 +96,9 @@ func convertToCompositeTagFilters(tfs *TagFilters) []*TagFilters {
 				continue
 			}
 			// Create composite filter on (name, tf)
-			compositeKey = marshalCompositeTagKey(compositeKey[:0], name, tf.key)
+			nameWithPrefix = append(nameWithPrefix[:0], namePrefix...)
+			nameWithPrefix = append(nameWithPrefix, name...)
+			compositeKey = marshalCompositeTagKey(compositeKey[:0], nameWithPrefix, tf.key)
 			var tfNew tagFilter
 			if err := tfNew.Init(tfs.commonPrefix, compositeKey, tf.value, tf.isNegative, tf.isRegexp); err != nil {
 				logger.Panicf("BUG: unexpected error when creating composite tag filter for name=%q and key=%q: %s", name, tf.key, err)
@@ -229,13 +233,18 @@ type tagFilter struct {
 	// matchCost is a cost for matching a filter against a single string.
 	matchCost uint64
 
+	// contains the prefix for regexp filter if isRegexp==true.
+	regexpPrefix string
+
 	// Prefix always contains {nsPrefixTagToMetricIDs, key}.
 	// Additionally it contains:
 	//  - value if !isRegexp.
-	//  - non-regexp prefix if isRegexp.
+	//  - regexpPrefix if isRegexp.
 	prefix []byte
 
-	// or values obtained from regexp suffix if it equals to "foo|bar|..."
+	// `or` values obtained from regexp suffix if it equals to "foo|bar|..."
+	//
+	// the regexp prefix is stored in regexpPrefix.
 	//
 	// This array is also populated with matching Graphite metrics if key="__graphite__"
 	orSuffixes []string
@@ -334,6 +343,7 @@ func (tf *tagFilter) InitFromGraphiteQuery(commonPrefix, query []byte, paths []s
 	tf.value = append(tf.value[:0], query...)
 	tf.isNegative = isNegative
 	tf.isRegexp = true // this is needed for tagFilter.matchSuffix
+	tf.regexpPrefix = prefix
 	tf.prefix = append(tf.prefix[:0], commonPrefix...)
 	tf.prefix = marshalTagValue(tf.prefix, nil)
 	tf.prefix = marshalTagValueNoTrailingTagSeparator(tf.prefix, []byte(prefix))
@@ -379,6 +389,7 @@ func (tf *tagFilter) Init(commonPrefix, key, value []byte, isNegative, isRegexp
 	tf.isRegexp = isRegexp
 	tf.matchCost = 0
 
+	tf.regexpPrefix = ""
 	tf.prefix = tf.prefix[:0]
 
 	tf.orSuffixes = tf.orSuffixes[:0]
@@ -396,6 +407,8 @@ func (tf *tagFilter) Init(commonPrefix, key, value []byte, isNegative, isRegexp
 		if len(expr) == 0 {
 			tf.value = append(tf.value[:0], prefix...)
 			tf.isRegexp = false
+		} else {
+			tf.regexpPrefix = string(prefix)
 		}
 	}
 	tf.prefix = marshalTagValueNoTrailingTagSeparator(tf.prefix, prefix)

lib/storage/tag_filters_test.go

@@ -410,6 +410,44 @@ func TestConvertToCompositeTagFilters(t *testing.T) {
 		},
 	})
 
+	// Multiple values regexp filter, which can be converted to non-regexp.
+	f([]TagFilter{
+		{
+			Key:        nil,
+			Value:      []byte("bar|foo"),
+			IsNegative: false,
+			IsRegexp:   true,
+		},
+	}, [][]TagFilter{
+		{
+			{
+				Key:        nil,
+				Value:      []byte("bar|foo"),
+				IsNegative: false,
+				IsRegexp:   true,
+			},
+		},
+	})
+
+	// Multiple values regexp filter with common prefix, which can be converted to non-regexp.
+	f([]TagFilter{
+		{
+			Key:        nil,
+			Value:      []byte("xxx(bar|foo)"),
+			IsNegative: false,
+			IsRegexp:   true,
+		},
+	}, [][]TagFilter{
+		{
+			{
+				Key:        nil,
+				Value:      []byte("xxx(bar|foo)"),
+				IsNegative: false,
+				IsRegexp:   true,
+			},
+		},
+	})
+
 	// Multiple values regexp filter, which can be converted to non-regexp, with non-name filter.
 	f([]TagFilter{
 		{
@@ -443,6 +481,39 @@ func TestConvertToCompositeTagFilters(t *testing.T) {
 		},
 	})
 
+	// Multiple values regexp filter with common prefix, which can be converted to non-regexp, with non-name filter.
+	f([]TagFilter{
+		{
+			Key:        nil,
+			Value:      []byte("xxx(bar|foox)"),
+			IsNegative: false,
+			IsRegexp:   true,
+		},
+		{
+			Key:        []byte("foo"),
+			Value:      []byte("abc"),
+			IsNegative: false,
+			IsRegexp:   false,
+		},
+	}, [][]TagFilter{
+		{
+			{
+				Key:        []byte("\xfe\x06xxxbarfoo"),
+				Value:      []byte("abc"),
+				IsNegative: false,
+				IsRegexp:   false,
+			},
+		},
+		{
+			{
+				Key:        []byte("\xfe\x07xxxfooxfoo"),
+				Value:      []byte("abc"),
+				IsNegative: false,
+				IsRegexp:   false,
+			},
+		},
+	})
+
 	// Two multiple values regexp filter, which can be converted to non-regexp, with non-name filter.
 	f([]TagFilter{
 		{