From ecf132933e52f4ecc25be9b5c6d61b8a0eb7458d Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@gmail.com>
Date: Mon, 15 Feb 2021 16:24:08 +0200
Subject: [PATCH] lib/storage: increase match cost for negative tag filters,
 since they need to scan all the label pairs

---
 lib/storage/index_db.go    |  2 +-
 lib/storage/tag_filters.go | 14 ++++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/lib/storage/index_db.go b/lib/storage/index_db.go
index 49aa87814..d7f29d73a 100644
--- a/lib/storage/index_db.go
+++ b/lib/storage/index_db.go
@@ -2804,7 +2804,7 @@ func (is *indexSearch) getMetricIDsForDateAndFilters(date uint64, tfs *TagFilter
 		if a.seconds != b.seconds {
 			return a.seconds < b.seconds
 		}
-		return a.tf.matchCost < b.tf.matchCost
+		return a.tf.Less(b.tf)
 	})
 
 	// Populate metricIDs for the first non-negative filter.
diff --git a/lib/storage/tag_filters.go b/lib/storage/tag_filters.go
index 60b340d9e..eae02771f 100644
--- a/lib/storage/tag_filters.go
+++ b/lib/storage/tag_filters.go
@@ -240,6 +240,9 @@ type tagFilter struct {
 func (tf *tagFilter) Less(other *tagFilter) bool {
 	// Move regexp and negative filters to the end, since they require scanning
 	// all the entries for the given label.
+	if tf.matchCost != other.matchCost {
+		return tf.matchCost < other.matchCost
+	}
 	if tf.isRegexp != other.isRegexp {
 		return !tf.isRegexp
 	}
@@ -312,6 +315,9 @@ func (tf *tagFilter) InitFromGraphiteQuery(commonPrefix, query []byte, paths []s
 	tf.prefix = marshalTagValueNoTrailingTagSeparator(tf.prefix, []byte(prefix))
 	tf.orSuffixes = append(tf.orSuffixes[:0], orSuffixes...)
 	tf.reSuffixMatch, tf.matchCost = newMatchFuncForOrSuffixes(orSuffixes)
+	if isNegative {
+		tf.matchCost *= negativeMatchCostMultiplier
+	}
 }
 
 func getCommonPrefix(ss []string) (string, []string) {
@@ -379,6 +385,9 @@ func (tf *tagFilter) Init(commonPrefix, key, value []byte, isNegative, isRegexp
 		tf.orSuffixes = append(tf.orSuffixes[:0], "")
 		tf.isEmptyMatch = len(prefix) == 0
 		tf.matchCost = fullMatchCost
+		if isNegative {
+			tf.matchCost *= negativeMatchCostMultiplier
+		}
 		return nil
 	}
 	rcv, err := getRegexpFromCache(expr)
@@ -388,6 +397,9 @@ func (tf *tagFilter) Init(commonPrefix, key, value []byte, isNegative, isRegexp
 	tf.orSuffixes = append(tf.orSuffixes[:0], rcv.orValues...)
 	tf.reSuffixMatch = rcv.reMatch
 	tf.matchCost = rcv.reCost
+	if isNegative {
+		tf.matchCost *= negativeMatchCostMultiplier
+	}
 	tf.isEmptyMatch = len(prefix) == 0 && tf.reSuffixMatch(nil)
 	if !tf.isNegative && len(key) == 0 && strings.IndexByte(rcv.literalSuffix, '.') >= 0 {
 		// Reverse suffix is needed only for non-negative regexp filters on __name__ that contains dots.
@@ -559,6 +571,8 @@ const (
 	reMatchCost      = 100
 )
 
+const negativeMatchCostMultiplier = 1000
+
 func getOptimizedReMatchFuncExt(reMatch func(b []byte) bool, sre *syntax.Regexp) (func(b []byte) bool, string, uint64) {
 	if isDotStar(sre) {
 		// '.*'