From d249d1d074c0db6e96b835abf0e54c8124721e1e Mon Sep 17 00:00:00 2001
From: naivewong <867245430@qq.com>
Date: Mon, 13 May 2019 21:53:28 +0800
Subject: [PATCH 01/19] Original version of the set optimization

Signed-off-by: naivewong <867245430@qq.com>
---
 labels/selector.go |  13 +-
 querier.go         | 362 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 369 insertions(+), 6 deletions(-)

diff --git a/labels/selector.go b/labels/selector.go
index a0565f57..c94ebb33 100644
--- a/labels/selector.go
+++ b/labels/selector.go
@@ -63,14 +63,15 @@ func NewEqualMatcher(name, value string) Matcher {
 	return &EqualMatcher{name: name, value: value}
 }
 
-type regexpMatcher struct {
+type RegexpMatcher struct {
 	name string
 	re   *regexp.Regexp
 }
 
-func (m regexpMatcher) Name() string          { return m.name }
-func (m regexpMatcher) Matches(v string) bool { return m.re.MatchString(v) }
-func (m regexpMatcher) String() string        { return fmt.Sprintf("%s=~%q", m.name, m.re.String()) }
+func (m RegexpMatcher) Name() string          { return m.name }
+func (m RegexpMatcher) Matches(v string) bool { return m.re.MatchString(v) }
+func (m RegexpMatcher) String() string        { return fmt.Sprintf("%s=~%q", m.name, m.re.String()) }
+func (m RegexpMatcher) Value() string         { return m.re.String() }
 
 // NewRegexpMatcher returns a new matcher verifying that a value matches
 // the regular expression pattern.
@@ -79,7 +80,7 @@ func NewRegexpMatcher(name, pattern string) (Matcher, error) {
 	if err != nil {
 		return nil, err
 	}
-	return &regexpMatcher{name: name, re: re}, nil
+	return &RegexpMatcher{name: name, re: re}, nil
 }
 
 // NewMustRegexpMatcher returns a new matcher verifying that a value matches
@@ -90,7 +91,7 @@ func NewMustRegexpMatcher(name, pattern string) Matcher {
 	if err != nil {
 		panic(err)
 	}
-	return &regexpMatcher{name: name, re: re}
+	return &RegexpMatcher{name: name, re: re}
 
 }
 
diff --git a/querier.go b/querier.go
index 9d99de08..99dc52c4 100644
--- a/querier.go
+++ b/querier.go
@@ -266,6 +266,350 @@ func (q *blockQuerier) Close() error {
 	return merr.Err()
 }
 
+func addStrToLevel(level []*strings.Builder, strs []string, idx int) []*strings.Builder {
+	levelSize := len(level) - idx
+	for j := idx + levelSize; j < idx + levelSize * len(strs); j ++ {
+		level = append(level, &strings.Builder{})
+		level[j].WriteString(level[j % levelSize + idx].String())
+	}
+	for i, s := range strs {
+		for j := idx + i * levelSize; j < idx + (i + 1) * levelSize; j ++ {
+			level[j].WriteString(s)
+		}
+	}
+	return level
+}
+
+func combineLevels(left []*strings.Builder, right []*strings.Builder, idx int) []*strings.Builder {
+	levelSize := len(left) - idx
+	for j := idx + levelSize; j < idx + levelSize * len(right); j ++ {
+		left = append(left, &strings.Builder{})
+		left[j].WriteString(left[idx + j % levelSize].String())
+	}
+	for i, s := range right {
+		for j := idx + i * levelSize; j < idx + (i + 1) * levelSize; j ++ {
+			left[j].WriteString(s.String())
+		}
+	}
+	return left
+}
+
+func handleEnd(pattern string, idx int) int {
+	escaped := false
+	for idx < len(pattern) {
+		switch c := pattern[idx]; {
+		case c == '$':
+			break
+		case c == '\\':
+			escaped = true
+			break
+		case c == 'B' && escaped:
+			escaped = false
+			break
+		default:
+
+		}
+		idx += 1
+	}
+	if idx == len(pattern) {
+		return idx
+	} else {
+		return -1
+	}
+}
+
+// Return empty array if not found.
+func findSetMatches(pattern string) []string {
+	// To detect the character '\'.
+	escaped := false
+	insideBrackets := false
+	insideBraces := false
+	combinePending := false
+	matches := []string{}
+	// This is to handle the nested parentheses.
+	levels := [][]*strings.Builder{[]*strings.Builder{&strings.Builder{}}}
+	barIdx := map[int]int{}
+	bracket := []string{}
+	i := 0
+	// Handle the beginning part of the pattern.
+Loop:
+	for i < len(pattern) {
+		switch c := pattern[i]; {
+		case c == '^':
+			break
+		case c == '\\':
+			escaped = true
+			break
+		case c == 'b' && escaped:
+			escaped = false
+			break
+		default:
+			break Loop
+		}
+		i += 1
+	}
+	// Handle the middle part of the pattern.
+	for i < len(pattern) {
+		if escaped {
+			switch c := pattern[i]; {
+			case c == 'B':
+				escaped = false
+				i = handleEnd(pattern, i + 1)
+				if i == -1 {
+					return []string{}
+				}
+				break
+			case c == '(' || c == ')' || c == '[' || c == '{' || c == '$' || c == '*' || c == '+' || c == '.' || c == '?' || c == '\\' || c == '^' || c == '|':
+				escaped = false
+				if idx, ok := barIdx[len(levels) - 1]; ok {
+					levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], []string{string(c)}, idx)
+				} else {
+					levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], []string{string(c)}, 0)
+				}
+			default:
+				return []string{}
+			}
+		} else if insideBrackets {
+			switch c := pattern[i]; {
+			case c == '^':
+				return []string{}
+			case c == ']':
+				if !(i + 1 < len(pattern) && pattern[i + 1] == '{') {
+					if idx, ok := barIdx[len(levels) - 1]; ok {
+						levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], bracket, idx)
+					} else {
+						levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], bracket, 0)
+					}
+					bracket = bracket[:0]
+				}
+				insideBrackets = false
+				break
+			case c == '-':
+				for ch := pattern[i - 1] + 1; ch <= pattern[i + 1]; ch ++ {
+					bracket = append(bracket, string(ch))
+				}
+				i += 1
+				break;
+			default:
+				bracket = append(bracket, string(pattern[i]))
+				break
+			}
+		} else if insideBraces {
+			start := 0
+			end := 0
+			left := false
+			comma := false
+			right := false
+			j := i
+			for pattern[j] != '}' {
+				if '0' <= pattern[j] && pattern[j] <= '9' {
+					if !comma {
+						left = true
+						start = start * 10 + int(pattern[j] - '0')
+					} else {
+						right = true
+						end = end * 10 + int(pattern[j] - '0')
+					}
+				} else if pattern[j] == ',' {
+					comma = true
+				} else {
+					return []string{}
+				}
+				j += 1
+			}
+			if !left {
+				if len(bracket) > 0 {
+					if idx, ok := barIdx[len(levels) - 1]; ok {
+						levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], bracket, idx)
+					} else {
+						levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], bracket, 0)
+					}
+					bracket = bracket[:0]
+				}
+				if idx, ok := barIdx[len(levels) - 1]; ok {
+					levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], []string{pattern[i - 1: j + 1]}, idx)
+				} else {
+					levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], []string{pattern[i - 1: j + 1]}, 0)
+				}
+			} else if comma {
+				if !right {
+					return []string{}
+				} else {
+					// Need further discussion.
+					l := 1
+					if len(bracket) > l {
+						l = len(bracket)
+					}
+					if combinePending && len(levels[len(levels) - 1]) > l {
+						l = len(levels[len(levels) - 1])
+					}
+					addStrs := make([]string, 0, (end - start + 1) * l)
+					if combinePending {
+						idx, ok := barIdx[len(levels) - 1]
+						if !ok {
+							idx = 0
+						}
+						for k := start; k <= end; k ++ {
+							for _, s := range levels[len(levels) - 1] {
+								addStrs = append(addStrs, strings.Repeat(s.String(), k))
+							}
+						}
+						levels[len(levels) - 1] = levels[len(levels) - 1][: idx + 1]
+						levels[len(levels) - 1][idx].Reset()
+						// Delete the bar index on the top level.
+						if _, ok = barIdx[len(levels) - 1]; ok {
+							delete(barIdx, len(levels) - 1)
+						}
+						levels = levels[: len(levels) - 1]
+						combinePending = false
+					} else if len(bracket) > 0 {
+						for k := start; k <= end; k ++ {
+							for _, s := range bracket {
+								addStrs = append(addStrs, strings.Repeat(s, k))
+							}
+						}
+						bracket = bracket[:0]
+					} else {
+						for k := start; k <= end; k ++ {
+							addStrs = append(addStrs, strings.Repeat(string(pattern[i - 2]), k))
+						}
+					}
+					if idx, ok := barIdx[len(levels) - 1]; ok {
+						levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], addStrs, idx)
+					} else {
+						levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], addStrs, 0)
+					}
+				}
+			} else {
+				l := 1
+				if len(bracket) > l {
+					l = len(bracket)
+				}
+				if combinePending && len(levels[len(levels) - 1]) > l {
+					l = len(levels[len(levels) - 1])
+				}
+				addStrs := make([]string, 0, l)
+				if combinePending {
+					idx, ok := barIdx[len(levels) - 1]
+					if !ok {
+						idx = 0
+					}
+					for _, s := range levels[len(levels) - 1] {
+						addStrs = append(addStrs, strings.Repeat(s.String(), start))
+					}
+					levels[len(levels) - 1] = levels[len(levels) - 1][: idx + 1]
+					levels[len(levels) - 1][idx].Reset()
+					// Delete the bar index on the top level.
+					if _, ok = barIdx[len(levels) - 1]; ok {
+						delete(barIdx, len(levels) - 1)
+					}
+					levels = levels[: len(levels) - 1]
+					combinePending = false
+				} else if len(bracket) > 0 {
+					for _, s := range bracket {
+						addStrs = append(addStrs, strings.Repeat(s, start))
+					}
+					bracket = bracket[:0]
+				} else {
+					addStrs = append(addStrs, strings.Repeat(string(pattern[i - 2]), start))
+				}
+				// fmt.Println("len addStrs", len(addStrs))
+				if idx, ok := barIdx[len(levels) - 1]; ok {
+					levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], addStrs, idx)
+				} else {
+					levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], addStrs, 0)
+				}
+			}
+			if combinePending {
+				if idx, ok := barIdx[len(levels) - 2]; ok {
+					levels[len(levels) - 2] = combineLevels(levels[len(levels) - 2], levels[len(levels) - 1], idx)
+				} else {
+					levels[len(levels) - 2] = combineLevels(levels[len(levels) - 2], levels[len(levels) - 1], 0)
+				}
+				// Delete the bar index on the top level.
+				if _, ok := barIdx[len(levels) - 1]; ok {
+					delete(barIdx, len(levels) - 1)
+				}
+				levels = levels[: len(levels) - 1]
+				combinePending = false
+			}
+			i = j
+			insideBraces = false
+		} else {
+			switch c := pattern[i]; {
+			case c == '*' || c == '+' || c == '.' || c == '?':
+				return []string{}
+			case c == '$':
+				i = handleEnd(pattern, i + 1)
+				if i == -1 {
+					return []string{}
+				}
+				break
+			case c == '\\':
+				escaped = true
+				break
+			case c == '[':
+				insideBrackets = true
+				break 
+			case c == '{':
+				insideBraces = true
+				break
+			case c == '(':
+				if i + 2 < len(pattern) && pattern[i + 1] == '?' && pattern[i + 2] == ':' {
+					i += 2
+				}
+				levels = append(levels, []*strings.Builder{&strings.Builder{}})
+				break
+			case c == ')':
+				// fmt.Println(len(levels))
+				if i + 1 < len(pattern) && pattern[i + 1] == '{' {
+					combinePending = true
+				} else {
+					if idx, ok := barIdx[len(levels) - 2]; ok {
+						levels[len(levels) - 2] = combineLevels(levels[len(levels) - 2], levels[len(levels) - 1], idx)
+					} else {
+						levels[len(levels) - 2] = combineLevels(levels[len(levels) - 2], levels[len(levels) - 1], 0)
+					}
+					// Delete the bar index on the top level.
+					if _, ok := barIdx[len(levels) - 1]; ok {
+						delete(barIdx, len(levels) - 1)
+					}
+					levels = levels[: len(levels) - 1]
+				}
+				break
+			case c == '|':
+				levels[len(levels) - 1] = append(levels[len(levels) - 1], &strings.Builder{})
+				barIdx[len(levels) - 1] = len(levels[len(levels) - 1]) - 1
+				break
+			default:
+				if len(bracket) > 0 {
+					if idx, ok := barIdx[len(levels) - 1]; ok {
+						levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], bracket, idx)
+					} else {
+						levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], bracket, 0)
+					}
+					bracket = bracket[:0]
+				} 
+				if !(i + 1 < len(pattern) && pattern[i + 1] == '{') {
+					if idx, ok := barIdx[len(levels) - 1]; ok {
+						levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], []string{string(c)}, idx)
+					} else {
+						levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], []string{string(c)}, 0)
+					}
+				}
+				break
+			}
+		}
+		i += 1
+	}
+	for _, s := range levels[0] {
+		if s.Len() > 0{
+			matches = append(matches, s.String())
+		}
+	}
+	return matches
+}
+
 // PostingsForMatchers assembles a single postings iterator against the index reader
 // based on the given matchers.
 func PostingsForMatchers(ix IndexReader, ms ...labels.Matcher) (index.Postings, error) {
@@ -346,6 +690,14 @@ func postingsForMatcher(ix IndexReader, m labels.Matcher) (index.Postings, error
 		return ix.Postings(em.Name(), em.Value())
 	}
 
+	// Fast-path for set matching.
+	if em, ok := m.(*labels.RegexpMatcher); ok {
+		setMatches := findSetMatches(em.Value())
+		if len(setMatches) > 0 {
+			return postingsForSetMatcher(ix, em.Name(), setMatches)
+		}
+	}
+
 	tpls, err := ix.LabelValues(m.Name())
 	if err != nil {
 		return nil, err
@@ -411,6 +763,16 @@ func inversePostingsForMatcher(ix IndexReader, m labels.Matcher) (index.Postings
 	return index.Merge(rit...), nil
 }
 
+func postingsForSetMatcher(ix IndexReader, name string, matches []string) (index.Postings, error) {
+	var its []index.Postings
+	for _, match := range matches {
+		if it, err := ix.Postings(name, match); err == nil {
+			its = append(its, it)
+		}
+	}
+	return index.Merge(its...), nil
+}
+
 func mergeStrings(a, b []string) []string {
 	maxl := len(a)
 	if len(b) > len(a) {

From 32080decc7755b2680e5f6841911429a7780ec75 Mon Sep 17 00:00:00 2001
From: naivewong <867245430@qq.com>
Date: Tue, 14 May 2019 12:16:37 +0800
Subject: [PATCH 02/19] simple set matcher

Signed-off-by: naivewong <867245430@qq.com>
---
 querier.go      | 348 ++++--------------------------------------------
 querier_test.go |  87 ++++++++++++
 2 files changed, 115 insertions(+), 320 deletions(-)

diff --git a/querier.go b/querier.go
index 99dc52c4..24db4bed 100644
--- a/querier.go
+++ b/querier.go
@@ -266,344 +266,52 @@ func (q *blockQuerier) Close() error {
 	return merr.Err()
 }
 
-func addStrToLevel(level []*strings.Builder, strs []string, idx int) []*strings.Builder {
-	levelSize := len(level) - idx
-	for j := idx + levelSize; j < idx + levelSize * len(strs); j ++ {
-		level = append(level, &strings.Builder{})
-		level[j].WriteString(level[j % levelSize + idx].String())
-	}
-	for i, s := range strs {
-		for j := idx + i * levelSize; j < idx + (i + 1) * levelSize; j ++ {
-			level[j].WriteString(s)
-		}
-	}
-	return level
-}
+// Bitmap used by func special to check whether a character needs to be escaped.
+var specialBytes [16]byte
 
-func combineLevels(left []*strings.Builder, right []*strings.Builder, idx int) []*strings.Builder {
-	levelSize := len(left) - idx
-	for j := idx + levelSize; j < idx + levelSize * len(right); j ++ {
-		left = append(left, &strings.Builder{})
-		left[j].WriteString(left[idx + j % levelSize].String())
-	}
-	for i, s := range right {
-		for j := idx + i * levelSize; j < idx + (i + 1) * levelSize; j ++ {
-			left[j].WriteString(s.String())
-		}
-	}
-	return left
+// special reports whether byte b needs to be escaped.
+func special(b byte) bool {
+	return b < utf8.RuneSelf && specialBytes[b%16]&(1<<(b/16)) != 0
 }
 
-func handleEnd(pattern string, idx int) int {
-	escaped := false
-	for idx < len(pattern) {
-		switch c := pattern[idx]; {
-		case c == '$':
-			break
-		case c == '\\':
-			escaped = true
-			break
-		case c == 'B' && escaped:
-			escaped = false
-			break
-		default:
-
-		}
-		idx += 1
-	}
-	if idx == len(pattern) {
-		return idx
-	} else {
-		return -1
+func init() {
+	for _, b := range []byte(`.+*?()|[]{}^$`) {
+		specialBytes[b%16] |= 1 << (b / 16)
 	}
 }
 
-// Return empty array if not found.
 func findSetMatches(pattern string) []string {
-	// To detect the character '\'.
 	escaped := false
-	insideBrackets := false
-	insideBraces := false
-	combinePending := false
-	matches := []string{}
-	// This is to handle the nested parentheses.
-	levels := [][]*strings.Builder{[]*strings.Builder{&strings.Builder{}}}
-	barIdx := map[int]int{}
-	bracket := []string{}
-	i := 0
-	// Handle the beginning part of the pattern.
-Loop:
-	for i < len(pattern) {
-		switch c := pattern[i]; {
-		case c == '^':
-			break
-		case c == '\\':
-			escaped = true
-			break
-		case c == 'b' && escaped:
-			escaped = false
-			break
-		default:
-			break Loop
-		}
-		i += 1
-	}
-	// Handle the middle part of the pattern.
-	for i < len(pattern) {
+	sets := []*strings.Builder{&strings.Builder{}}
+	for i := 0; i < len(pattern); i ++ {
 		if escaped {
-			switch c := pattern[i]; {
-			case c == 'B':
-				escaped = false
-				i = handleEnd(pattern, i + 1)
-				if i == -1 {
-					return []string{}
-				}
-				break
-			case c == '(' || c == ')' || c == '[' || c == '{' || c == '$' || c == '*' || c == '+' || c == '.' || c == '?' || c == '\\' || c == '^' || c == '|':
-				escaped = false
-				if idx, ok := barIdx[len(levels) - 1]; ok {
-					levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], []string{string(c)}, idx)
-				} else {
-					levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], []string{string(c)}, 0)
-				}
-			default:
-				return []string{}
-			}
-		} else if insideBrackets {
-			switch c := pattern[i]; {
-			case c == '^':
-				return []string{}
-			case c == ']':
-				if !(i + 1 < len(pattern) && pattern[i + 1] == '{') {
-					if idx, ok := barIdx[len(levels) - 1]; ok {
-						levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], bracket, idx)
-					} else {
-						levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], bracket, 0)
-					}
-					bracket = bracket[:0]
-				}
-				insideBrackets = false
-				break
-			case c == '-':
-				for ch := pattern[i - 1] + 1; ch <= pattern[i + 1]; ch ++ {
-					bracket = append(bracket, string(ch))
-				}
-				i += 1
-				break;
-			default:
-				bracket = append(bracket, string(pattern[i]))
-				break
-			}
-		} else if insideBraces {
-			start := 0
-			end := 0
-			left := false
-			comma := false
-			right := false
-			j := i
-			for pattern[j] != '}' {
-				if '0' <= pattern[j] && pattern[j] <= '9' {
-					if !comma {
-						left = true
-						start = start * 10 + int(pattern[j] - '0')
-					} else {
-						right = true
-						end = end * 10 + int(pattern[j] - '0')
-					}
-				} else if pattern[j] == ',' {
-					comma = true
-				} else {
-					return []string{}
-				}
-				j += 1
-			}
-			if !left {
-				if len(bracket) > 0 {
-					if idx, ok := barIdx[len(levels) - 1]; ok {
-						levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], bracket, idx)
-					} else {
-						levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], bracket, 0)
-					}
-					bracket = bracket[:0]
-				}
-				if idx, ok := barIdx[len(levels) - 1]; ok {
-					levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], []string{pattern[i - 1: j + 1]}, idx)
-				} else {
-					levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], []string{pattern[i - 1: j + 1]}, 0)
-				}
-			} else if comma {
-				if !right {
-					return []string{}
-				} else {
-					// Need further discussion.
-					l := 1
-					if len(bracket) > l {
-						l = len(bracket)
-					}
-					if combinePending && len(levels[len(levels) - 1]) > l {
-						l = len(levels[len(levels) - 1])
-					}
-					addStrs := make([]string, 0, (end - start + 1) * l)
-					if combinePending {
-						idx, ok := barIdx[len(levels) - 1]
-						if !ok {
-							idx = 0
-						}
-						for k := start; k <= end; k ++ {
-							for _, s := range levels[len(levels) - 1] {
-								addStrs = append(addStrs, strings.Repeat(s.String(), k))
-							}
-						}
-						levels[len(levels) - 1] = levels[len(levels) - 1][: idx + 1]
-						levels[len(levels) - 1][idx].Reset()
-						// Delete the bar index on the top level.
-						if _, ok = barIdx[len(levels) - 1]; ok {
-							delete(barIdx, len(levels) - 1)
-						}
-						levels = levels[: len(levels) - 1]
-						combinePending = false
-					} else if len(bracket) > 0 {
-						for k := start; k <= end; k ++ {
-							for _, s := range bracket {
-								addStrs = append(addStrs, strings.Repeat(s, k))
-							}
-						}
-						bracket = bracket[:0]
-					} else {
-						for k := start; k <= end; k ++ {
-							addStrs = append(addStrs, strings.Repeat(string(pattern[i - 2]), k))
-						}
-					}
-					if idx, ok := barIdx[len(levels) - 1]; ok {
-						levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], addStrs, idx)
-					} else {
-						levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], addStrs, 0)
-					}
-				}
+			// Add the escaped special character to the sets.
+			if special(pattern[i]) {
+				sets[len(sets)-1].WriteByte(pattern[i])
+			} else if pattern[i] == '\\' {
+				sets[len(sets)-1].WriteByte('\\')
 			} else {
-				l := 1
-				if len(bracket) > l {
-					l = len(bracket)
-				}
-				if combinePending && len(levels[len(levels) - 1]) > l {
-					l = len(levels[len(levels) - 1])
-				}
-				addStrs := make([]string, 0, l)
-				if combinePending {
-					idx, ok := barIdx[len(levels) - 1]
-					if !ok {
-						idx = 0
-					}
-					for _, s := range levels[len(levels) - 1] {
-						addStrs = append(addStrs, strings.Repeat(s.String(), start))
-					}
-					levels[len(levels) - 1] = levels[len(levels) - 1][: idx + 1]
-					levels[len(levels) - 1][idx].Reset()
-					// Delete the bar index on the top level.
-					if _, ok = barIdx[len(levels) - 1]; ok {
-						delete(barIdx, len(levels) - 1)
-					}
-					levels = levels[: len(levels) - 1]
-					combinePending = false
-				} else if len(bracket) > 0 {
-					for _, s := range bracket {
-						addStrs = append(addStrs, strings.Repeat(s, start))
-					}
-					bracket = bracket[:0]
-				} else {
-					addStrs = append(addStrs, strings.Repeat(string(pattern[i - 2]), start))
-				}
-				// fmt.Println("len addStrs", len(addStrs))
-				if idx, ok := barIdx[len(levels) - 1]; ok {
-					levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], addStrs, idx)
-				} else {
-					levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], addStrs, 0)
-				}
-			}
-			if combinePending {
-				if idx, ok := barIdx[len(levels) - 2]; ok {
-					levels[len(levels) - 2] = combineLevels(levels[len(levels) - 2], levels[len(levels) - 1], idx)
-				} else {
-					levels[len(levels) - 2] = combineLevels(levels[len(levels) - 2], levels[len(levels) - 1], 0)
-				}
-				// Delete the bar index on the top level.
-				if _, ok := barIdx[len(levels) - 1]; ok {
-					delete(barIdx, len(levels) - 1)
-				}
-				levels = levels[: len(levels) - 1]
-				combinePending = false
+				return []string{}
 			}
-			i = j
-			insideBraces = false
+			escaped = false
 		} else {
-			switch c := pattern[i]; {
-			case c == '*' || c == '+' || c == '.' || c == '?':
-				return []string{}
-			case c == '$':
-				i = handleEnd(pattern, i + 1)
-				if i == -1 {
+			// Return empty sets when there are special characters excluding '|'.
+			if special(pattern[i]) {
+				if pattern[i] == '|' {
+					sets = append(sets, &strings.Builder{})
+				} else {
 					return []string{}
 				}
-				break
-			case c == '\\':
+			} else if pattern[i] == '\\' {
 				escaped = true
-				break
-			case c == '[':
-				insideBrackets = true
-				break 
-			case c == '{':
-				insideBraces = true
-				break
-			case c == '(':
-				if i + 2 < len(pattern) && pattern[i + 1] == '?' && pattern[i + 2] == ':' {
-					i += 2
-				}
-				levels = append(levels, []*strings.Builder{&strings.Builder{}})
-				break
-			case c == ')':
-				// fmt.Println(len(levels))
-				if i + 1 < len(pattern) && pattern[i + 1] == '{' {
-					combinePending = true
-				} else {
-					if idx, ok := barIdx[len(levels) - 2]; ok {
-						levels[len(levels) - 2] = combineLevels(levels[len(levels) - 2], levels[len(levels) - 1], idx)
-					} else {
-						levels[len(levels) - 2] = combineLevels(levels[len(levels) - 2], levels[len(levels) - 1], 0)
-					}
-					// Delete the bar index on the top level.
-					if _, ok := barIdx[len(levels) - 1]; ok {
-						delete(barIdx, len(levels) - 1)
-					}
-					levels = levels[: len(levels) - 1]
-				}
-				break
-			case c == '|':
-				levels[len(levels) - 1] = append(levels[len(levels) - 1], &strings.Builder{})
-				barIdx[len(levels) - 1] = len(levels[len(levels) - 1]) - 1
-				break
-			default:
-				if len(bracket) > 0 {
-					if idx, ok := barIdx[len(levels) - 1]; ok {
-						levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], bracket, idx)
-					} else {
-						levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], bracket, 0)
-					}
-					bracket = bracket[:0]
-				} 
-				if !(i + 1 < len(pattern) && pattern[i + 1] == '{') {
-					if idx, ok := barIdx[len(levels) - 1]; ok {
-						levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], []string{string(c)}, idx)
-					} else {
-						levels[len(levels) - 1] = addStrToLevel(levels[len(levels) - 1], []string{string(c)}, 0)
-					}
-				}
-				break
+			} else {
+				sets[len(sets)-1].WriteByte(pattern[i])
 			}
 		}
-		i += 1
 	}
-	for _, s := range levels[0] {
-		if s.Len() > 0{
+	matches := make([]string, 0, len(sets))
+	for _, s := range sets {
+		if s.Len() > 0 {
 			matches = append(matches, s.String())
 		}
 	}
diff --git a/querier_test.go b/querier_test.go
index cb53462a..de3ca405 100644
--- a/querier_test.go
+++ b/querier_test.go
@@ -1691,6 +1691,57 @@ func BenchmarkQuerySeek(b *testing.B) {
 	}
 }
 
+// Refer to https://github.com/prometheus/prometheus/issues/2651.
+func TestFindSetMatches(t *testing.T) {
+	cases := []struct {
+		pattern string
+		exp     []string
+	}{
+		// Simple sets.
+		{
+			pattern: "foo|bar|baz",
+			exp: []string{
+				"foo", 
+				"bar", 
+				"baz",
+			},
+		},
+		// Simple sets containing escaped characters.
+		{
+			pattern: "fo\\.o|bar\\?|\\^baz",
+			exp: []string{
+				"fo.o", 
+				"bar?", 
+				"^baz",
+			},
+		},
+		// Simple sets containing special characters without escaping.
+		{
+			pattern: "fo.o|bar?|^baz",
+			exp:     []string{},
+		},
+	}
+
+	for _, c := range cases {
+		matches := findSetMatches(c.pattern)
+		if len(c.exp) == 0 {
+			if len(matches) != 0 {
+				t.Errorf("Evaluating %s, unexpected result %v", c.pattern, matches)
+			}
+		} else {
+			if len(matches) != len(c.exp) {
+				t.Errorf("Evaluating %s, length of result not equal to exp", c.pattern)
+			} else {
+				for i := 0; i < len(c.exp); i ++ {
+					if c.exp[i] != matches[i] {
+						t.Errorf("Evaluating %s, unexpected result %s", c.pattern, matches[i])
+					}
+				}
+			}
+		}
+	}
+}
+
 func TestPostingsForMatchers(t *testing.T) {
 	h, err := NewHead(nil, nil, nil, 1000)
 	testutil.Ok(t, err)
@@ -1703,6 +1754,7 @@ func TestPostingsForMatchers(t *testing.T) {
 	app.Add(labels.FromStrings("n", "1", "i", "a"), 0, 0)
 	app.Add(labels.FromStrings("n", "1", "i", "b"), 0, 0)
 	app.Add(labels.FromStrings("n", "2"), 0, 0)
+	app.Add(labels.FromStrings("n", "2.5"), 0, 0)
 	testutil.Ok(t, app.Commit())
 
 	cases := []struct {
@@ -1735,6 +1787,7 @@ func TestPostingsForMatchers(t *testing.T) {
 				labels.FromStrings("n", "1", "i", "a"),
 				labels.FromStrings("n", "1", "i", "b"),
 				labels.FromStrings("n", "2"),
+				labels.FromStrings("n", "2.5"),
 			},
 		},
 		// Not equals.
@@ -1742,6 +1795,7 @@ func TestPostingsForMatchers(t *testing.T) {
 			matchers: []labels.Matcher{labels.Not(labels.NewEqualMatcher("n", "1"))},
 			exp: []labels.Labels{
 				labels.FromStrings("n", "2"),
+				labels.FromStrings("n", "2.5"),
 			},
 		},
 		{
@@ -1796,6 +1850,7 @@ func TestPostingsForMatchers(t *testing.T) {
 			exp: []labels.Labels{
 				labels.FromStrings("n", "1"),
 				labels.FromStrings("n", "2"),
+				labels.FromStrings("n", "2.5"),
 			},
 		},
 		{
@@ -1824,6 +1879,7 @@ func TestPostingsForMatchers(t *testing.T) {
 			matchers: []labels.Matcher{labels.Not(labels.NewMustRegexpMatcher("n", "^1$"))},
 			exp: []labels.Labels{
 				labels.FromStrings("n", "2"),
+				labels.FromStrings("n", "2.5"),
 			},
 		},
 		{
@@ -1869,6 +1925,37 @@ func TestPostingsForMatchers(t *testing.T) {
 				labels.FromStrings("n", "1", "i", "a"),
 			},
 		},
+		// Set optimization for Regex.
+		// Refer to https://github.com/prometheus/prometheus/issues/2651.
+		{
+			matchers: []labels.Matcher{labels.NewMustRegexpMatcher("n", "1|2")},
+			exp: []labels.Labels{
+				labels.FromStrings("n", "1"),
+				labels.FromStrings("n", "1", "i", "a"),
+				labels.FromStrings("n", "1", "i", "b"),
+				labels.FromStrings("n", "2"),
+			},
+		},
+		{
+			matchers: []labels.Matcher{labels.NewMustRegexpMatcher("i", "a|b")},
+			exp: []labels.Labels{
+				labels.FromStrings("n", "1", "i", "a"),
+				labels.FromStrings("n", "1", "i", "b"),
+			},
+		},
+		{
+			matchers: []labels.Matcher{labels.NewMustRegexpMatcher("n", "x1|2")},
+			exp: []labels.Labels{
+				labels.FromStrings("n", "2"),
+			},
+		},
+		{
+			matchers: []labels.Matcher{labels.NewMustRegexpMatcher("n", "2|2\\.5")},
+			exp: []labels.Labels{
+				labels.FromStrings("n", "2"),
+				labels.FromStrings("n", "2.5"),
+			},
+		},
 	}
 
 	ir, err := h.Index()

From 3f60bf8a877ae636b6499d5d8fc9567d10daf331 Mon Sep 17 00:00:00 2001
From: naivewong <867245430@qq.com>
Date: Tue, 14 May 2019 12:23:46 +0800
Subject: [PATCH 03/19] simple set matcher

Signed-off-by: naivewong <867245430@qq.com>
---
 querier.go | 1 +
 1 file changed, 1 insertion(+)

diff --git a/querier.go b/querier.go
index 24db4bed..9acf651d 100644
--- a/querier.go
+++ b/querier.go
@@ -17,6 +17,7 @@ import (
 	"fmt"
 	"sort"
 	"strings"
+	"unicode/utf8"
 
 	"github.com/pkg/errors"
 	"github.com/prometheus/tsdb/chunkenc"

From 02dfa44a19b197e3c8128bd3f70b37ea8f42091d Mon Sep 17 00:00:00 2001
From: naivewong <867245430@qq.com>
Date: Tue, 14 May 2019 12:37:48 +0800
Subject: [PATCH 04/19] update

Signed-off-by: naivewong <867245430@qq.com>
---
 querier.go      |  2 +-
 querier_test.go | 10 +++++-----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/querier.go b/querier.go
index 9acf651d..97d989c4 100644
--- a/querier.go
+++ b/querier.go
@@ -284,7 +284,7 @@ func init() {
 func findSetMatches(pattern string) []string {
 	escaped := false
 	sets := []*strings.Builder{&strings.Builder{}}
-	for i := 0; i < len(pattern); i ++ {
+	for i := 0; i < len(pattern); i++ {
 		if escaped {
 			// Add the escaped special character to the sets.
 			if special(pattern[i]) {
diff --git a/querier_test.go b/querier_test.go
index de3ca405..45fc2a48 100644
--- a/querier_test.go
+++ b/querier_test.go
@@ -1701,8 +1701,8 @@ func TestFindSetMatches(t *testing.T) {
 		{
 			pattern: "foo|bar|baz",
 			exp: []string{
-				"foo", 
-				"bar", 
+				"foo",
+				"bar",
 				"baz",
 			},
 		},
@@ -1710,8 +1710,8 @@ func TestFindSetMatches(t *testing.T) {
 		{
 			pattern: "fo\\.o|bar\\?|\\^baz",
 			exp: []string{
-				"fo.o", 
-				"bar?", 
+				"fo.o",
+				"bar?",
 				"^baz",
 			},
 		},
@@ -1732,7 +1732,7 @@ func TestFindSetMatches(t *testing.T) {
 			if len(matches) != len(c.exp) {
 				t.Errorf("Evaluating %s, length of result not equal to exp", c.pattern)
 			} else {
-				for i := 0; i < len(c.exp); i ++ {
+				for i := 0; i < len(c.exp); i++ {
 					if c.exp[i] != matches[i] {
 						t.Errorf("Evaluating %s, unexpected result %s", c.pattern, matches[i])
 					}

From 842e2a465dcc18ff29782b9de294c2b4678f7968 Mon Sep 17 00:00:00 2001
From: naivewong <867245430@qq.com>
Date: Tue, 14 May 2019 17:45:56 +0800
Subject: [PATCH 05/19] update

Signed-off-by: naivewong <867245430@qq.com>
---
 querier.go      |  6 +++++-
 querier_test.go | 19 ++++++++++++-------
 2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/querier.go b/querier.go
index 97d989c4..f6f7f658 100644
--- a/querier.go
+++ b/querier.go
@@ -282,9 +282,13 @@ func init() {
 }
 
 func findSetMatches(pattern string) []string {
+	// Return empty matches if the wrapper from Prometheus is missing.
+	if len(pattern) < 6 || pattern[:4] != "^(?:" || pattern[len(pattern)-2:] != ")$" {
+		return []string{}
+	}
 	escaped := false
 	sets := []*strings.Builder{&strings.Builder{}}
-	for i := 0; i < len(pattern); i++ {
+	for i := 4; i < len(pattern)-2; i++ {
 		if escaped {
 			// Add the escaped special character to the sets.
 			if special(pattern[i]) {
diff --git a/querier_test.go b/querier_test.go
index 45fc2a48..15138467 100644
--- a/querier_test.go
+++ b/querier_test.go
@@ -1699,7 +1699,7 @@ func TestFindSetMatches(t *testing.T) {
 	}{
 		// Simple sets.
 		{
-			pattern: "foo|bar|baz",
+			pattern: "^(?:foo|bar|baz)$",
 			exp: []string{
 				"foo",
 				"bar",
@@ -1708,7 +1708,7 @@ func TestFindSetMatches(t *testing.T) {
 		},
 		// Simple sets containing escaped characters.
 		{
-			pattern: "fo\\.o|bar\\?|\\^baz",
+			pattern: "^(?:fo\\.o|bar\\?|\\^baz)$",
 			exp: []string{
 				"fo.o",
 				"bar?",
@@ -1717,7 +1717,12 @@ func TestFindSetMatches(t *testing.T) {
 		},
 		// Simple sets containing special characters without escaping.
 		{
-			pattern: "fo.o|bar?|^baz",
+			pattern: "^(?:fo.o|bar?|^baz)$",
+			exp:     []string{},
+		},
+		// Missing wrapper.
+		{
+			pattern: "foo|bar|baz",
 			exp:     []string{},
 		},
 	}
@@ -1928,7 +1933,7 @@ func TestPostingsForMatchers(t *testing.T) {
 		// Set optimization for Regex.
 		// Refer to https://github.com/prometheus/prometheus/issues/2651.
 		{
-			matchers: []labels.Matcher{labels.NewMustRegexpMatcher("n", "1|2")},
+			matchers: []labels.Matcher{labels.NewMustRegexpMatcher("n", "^(?:1|2)$")},
 			exp: []labels.Labels{
 				labels.FromStrings("n", "1"),
 				labels.FromStrings("n", "1", "i", "a"),
@@ -1937,20 +1942,20 @@ func TestPostingsForMatchers(t *testing.T) {
 			},
 		},
 		{
-			matchers: []labels.Matcher{labels.NewMustRegexpMatcher("i", "a|b")},
+			matchers: []labels.Matcher{labels.NewMustRegexpMatcher("i", "^(?:a|b)$")},
 			exp: []labels.Labels{
 				labels.FromStrings("n", "1", "i", "a"),
 				labels.FromStrings("n", "1", "i", "b"),
 			},
 		},
 		{
-			matchers: []labels.Matcher{labels.NewMustRegexpMatcher("n", "x1|2")},
+			matchers: []labels.Matcher{labels.NewMustRegexpMatcher("n", "^(?:x1|2)$")},
 			exp: []labels.Labels{
 				labels.FromStrings("n", "2"),
 			},
 		},
 		{
-			matchers: []labels.Matcher{labels.NewMustRegexpMatcher("n", "2|2\\.5")},
+			matchers: []labels.Matcher{labels.NewMustRegexpMatcher("n", "^(?:2|2\\.5)$")},
 			exp: []labels.Labels{
 				labels.FromStrings("n", "2"),
 				labels.FromStrings("n", "2.5"),

From 1e3cf631d7cadf8a032801484df7fc743373176a Mon Sep 17 00:00:00 2001
From: naivewong <867245430@qq.com>
Date: Wed, 15 May 2019 11:09:47 +0800
Subject: [PATCH 06/19] add benchmark

Signed-off-by: naivewong <867245430@qq.com>
---
 querier_test.go | 112 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 112 insertions(+)

diff --git a/querier_test.go b/querier_test.go
index 15138467..feae89c3 100644
--- a/querier_test.go
+++ b/querier_test.go
@@ -1691,6 +1691,118 @@ func BenchmarkQuerySeek(b *testing.B) {
 	}
 }
 
+func BenchmarkSetMatcher(b *testing.B) {
+	cases := []struct {
+		numBlocks                   int
+		numSeries                   int
+		numSamplesPerSeriesPerBlock int
+		setPattern                  string
+		regexPattern                string
+	}{
+		{
+			numBlocks:                   1,
+			numSeries:                   15,
+			numSamplesPerSeriesPerBlock: 10,
+			setPattern:                  "^(?:1|2|3)$",
+			regexPattern:                "1|2|3",
+		},
+		{
+			numBlocks:                   1,
+			numSeries:                   15,
+			numSamplesPerSeriesPerBlock: 10, 
+			setPattern:                  "^(?:1|2|3|4|5|6|7|8|9|10)$",
+			regexPattern:                "1|2|3|4|5|6|7|8|9|10",
+		},
+		{
+			numBlocks:                   1,
+			numSeries:                   200,
+			numSamplesPerSeriesPerBlock: 10,
+			setPattern:                  "^(?:1|2|3)$",
+			regexPattern:                "1|2|3",
+		},
+		{
+			numBlocks:                   1,
+			numSeries:                   200,
+			numSamplesPerSeriesPerBlock: 10, 
+			setPattern:                  "^(?:1|2|3|4|5|6|7|8|9|10)$",
+			regexPattern:                "1|2|3|4|5|6|7|8|9|10",
+		},
+	}
+
+	for _, c := range cases {
+		dir, err := ioutil.TempDir("", "bench_postings_for_matchers")
+		testutil.Ok(b, err)
+		defer func() {
+			testutil.Ok(b, os.RemoveAll(dir))
+		}()
+
+		var (
+			blocks          []*Block
+			prefilledLabels []map[string]string
+			generatedSeries []Series
+		)
+		for i := int64(0); i < int64(c.numBlocks); i++ {
+			mint := i*int64(c.numSamplesPerSeriesPerBlock)
+			maxt := mint + int64(c.numSamplesPerSeriesPerBlock) - 1
+			if len(prefilledLabels) == 0 {
+				generatedSeries = make([]Series, c.numSeries)
+				for i := 0; i < c.numSeries; i++ {
+					lbls := make(map[string]string, 10)
+					// The first label pair is {"test", "i"} which is for benchmarking set matcher.
+					lbls["test"] = strconv.Itoa(i)
+					for len(lbls) < 10 {
+						lbls[randString()] = randString()
+					}
+					samples := make([]tsdbutil.Sample, 0, maxt-mint+1)
+					for t := mint; t <= maxt; t++ {
+						samples = append(samples, sample{t: t, v: rand.Float64()})
+					}
+					generatedSeries[i] = newSeries(lbls, samples)
+				}
+				for _, s := range generatedSeries {
+					prefilledLabels = append(prefilledLabels, s.Labels().Map())
+				}
+			} else {
+				generatedSeries = populateSeries(prefilledLabels, mint, maxt)
+			}
+			block, err := OpenBlock(nil, createBlock(b, dir, generatedSeries), nil)
+			testutil.Ok(b, err)
+			blocks = append(blocks, block)
+			defer block.Close()
+		}
+
+		que := &querier{
+			blocks: make([]Querier, 0, len(blocks)),
+		}
+		for _, blk := range blocks {
+			q, err := NewBlockQuerier(blk, math.MinInt64, math.MaxInt64)
+			testutil.Ok(b, err)
+			que.blocks = append(que.blocks, q)
+		}
+		defer que.Close()
+
+		benchMsg1 := fmt.Sprintf("SetMatch,nSeries=%d,pattern=\"%s\"", c.numSeries, c.setPattern)
+		benchMsg2 := fmt.Sprintf("RegexMatch,nSeries=%d,pattern=\"%s\"", c.numSeries, c.regexPattern)
+		b.Run(benchMsg1, func(b *testing.B) {
+			b.ResetTimer()
+			b.ReportAllocs()
+			for n := 0; n < b.N; n++ {
+				_, err := que.Select(labels.NewMustRegexpMatcher("test", c.setPattern))
+				testutil.Ok(b, err)
+
+			}
+		})
+		b.Run(benchMsg2, func(b *testing.B) {
+			b.ResetTimer()
+			b.ReportAllocs()
+			for n := 0; n < b.N; n++ {
+				_, err := que.Select(labels.NewMustRegexpMatcher("test", c.regexPattern))
+				testutil.Ok(b, err)
+			}
+		})
+	}
+}
+
 // Refer to https://github.com/prometheus/prometheus/issues/2651.
 func TestFindSetMatches(t *testing.T) {
 	cases := []struct {

From 4a66e349951a8555d0e43bd46118377d9261560b Mon Sep 17 00:00:00 2001
From: naivewong <867245430@qq.com>
Date: Wed, 15 May 2019 11:12:56 +0800
Subject: [PATCH 07/19] update

Signed-off-by: naivewong <867245430@qq.com>
---
 querier_test.go | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/querier_test.go b/querier_test.go
index feae89c3..2d713435 100644
--- a/querier_test.go
+++ b/querier_test.go
@@ -1709,7 +1709,7 @@ func BenchmarkSetMatcher(b *testing.B) {
 		{
 			numBlocks:                   1,
 			numSeries:                   15,
-			numSamplesPerSeriesPerBlock: 10, 
+			numSamplesPerSeriesPerBlock: 10,
 			setPattern:                  "^(?:1|2|3|4|5|6|7|8|9|10)$",
 			regexPattern:                "1|2|3|4|5|6|7|8|9|10",
 		},
@@ -1723,7 +1723,7 @@ func BenchmarkSetMatcher(b *testing.B) {
 		{
 			numBlocks:                   1,
 			numSeries:                   200,
-			numSamplesPerSeriesPerBlock: 10, 
+			numSamplesPerSeriesPerBlock: 10,
 			setPattern:                  "^(?:1|2|3|4|5|6|7|8|9|10)$",
 			regexPattern:                "1|2|3|4|5|6|7|8|9|10",
 		},
@@ -1742,7 +1742,7 @@ func BenchmarkSetMatcher(b *testing.B) {
 			generatedSeries []Series
 		)
 		for i := int64(0); i < int64(c.numBlocks); i++ {
-			mint := i*int64(c.numSamplesPerSeriesPerBlock)
+			mint := i * int64(c.numSamplesPerSeriesPerBlock)
 			maxt := mint + int64(c.numSamplesPerSeriesPerBlock) - 1
 			if len(prefilledLabels) == 0 {
 				generatedSeries = make([]Series, c.numSeries)

From 87c3186db6fcc1dbad6a9bbac8cc670109cd7a2a Mon Sep 17 00:00:00 2001
From: naivewong <867245430@qq.com>
Date: Wed, 15 May 2019 11:20:42 +0800
Subject: [PATCH 08/19] update

Signed-off-by: naivewong <867245430@qq.com>
---
 querier_test.go | 1 +
 1 file changed, 1 insertion(+)

diff --git a/querier_test.go b/querier_test.go
index 2d713435..17e80218 100644
--- a/querier_test.go
+++ b/querier_test.go
@@ -21,6 +21,7 @@ import (
 	"os"
 	"path/filepath"
 	"sort"
+	"strconv"
 	"testing"
 
 	"github.com/pkg/errors"

From 017871f2b62c5a3b65cfe61f499f6a47176ebfcb Mon Sep 17 00:00:00 2001
From: naivewong <867245430@qq.com>
Date: Wed, 15 May 2019 16:03:57 +0800
Subject: [PATCH 09/19] update benchmark

Signed-off-by: naivewong <867245430@qq.com>
---
 querier_test.go | 49 ++++++++++++++++++-------------------------------
 1 file changed, 18 insertions(+), 31 deletions(-)

diff --git a/querier_test.go b/querier_test.go
index 17e80218..18d23a58 100644
--- a/querier_test.go
+++ b/querier_test.go
@@ -1692,41 +1692,37 @@ func BenchmarkQuerySeek(b *testing.B) {
 	}
 }
 
+// Refer to https://github.com/prometheus/prometheus/issues/2651.
 func BenchmarkSetMatcher(b *testing.B) {
 	cases := []struct {
 		numBlocks                   int
 		numSeries                   int
 		numSamplesPerSeriesPerBlock int
-		setPattern                  string
-		regexPattern                string
+		pattern                     string
 	}{
 		{
 			numBlocks:                   1,
 			numSeries:                   15,
 			numSamplesPerSeriesPerBlock: 10,
-			setPattern:                  "^(?:1|2|3)$",
-			regexPattern:                "1|2|3",
+			pattern:                     "^(?:1|2|3)$",
 		},
 		{
 			numBlocks:                   1,
 			numSeries:                   15,
-			numSamplesPerSeriesPerBlock: 10,
-			setPattern:                  "^(?:1|2|3|4|5|6|7|8|9|10)$",
-			regexPattern:                "1|2|3|4|5|6|7|8|9|10",
+			numSamplesPerSeriesPerBlock: 10, 
+			pattern:                     "^(?:1|2|3|4|5|6|7|8|9|10)$",
 		},
 		{
-			numBlocks:                   1,
-			numSeries:                   200,
+			numBlocks:                   20,
+			numSeries:                   1000,
 			numSamplesPerSeriesPerBlock: 10,
-			setPattern:                  "^(?:1|2|3)$",
-			regexPattern:                "1|2|3",
+			pattern:                     "^(?:1|2|3)$",
 		},
 		{
-			numBlocks:                   1,
-			numSeries:                   200,
-			numSamplesPerSeriesPerBlock: 10,
-			setPattern:                  "^(?:1|2|3|4|5|6|7|8|9|10)$",
-			regexPattern:                "1|2|3|4|5|6|7|8|9|10",
+			numBlocks:                   20,
+			numSeries:                   1000,
+			numSamplesPerSeriesPerBlock: 10, 
+			pattern:                     "^(?:1|2|3|4|5|6|7|8|9|10)$",
 		},
 	}
 
@@ -1743,14 +1739,14 @@ func BenchmarkSetMatcher(b *testing.B) {
 			generatedSeries []Series
 		)
 		for i := int64(0); i < int64(c.numBlocks); i++ {
-			mint := i * int64(c.numSamplesPerSeriesPerBlock)
+			mint := i*int64(c.numSamplesPerSeriesPerBlock)
 			maxt := mint + int64(c.numSamplesPerSeriesPerBlock) - 1
 			if len(prefilledLabels) == 0 {
 				generatedSeries = make([]Series, c.numSeries)
 				for i := 0; i < c.numSeries; i++ {
 					lbls := make(map[string]string, 10)
-					// The first label pair is {"test", "i"} which is for benchmarking set matcher.
-					lbls["test"] = strconv.Itoa(i)
+					// The first label pair is {"test", "i%50"} which is for benchmarking set matcher.
+					lbls["test"] = strconv.Itoa(i%50)
 					for len(lbls) < 10 {
 						lbls[randString()] = randString()
 					}
@@ -1782,25 +1778,16 @@ func BenchmarkSetMatcher(b *testing.B) {
 		}
 		defer que.Close()
 
-		benchMsg1 := fmt.Sprintf("SetMatch,nSeries=%d,pattern=\"%s\"", c.numSeries, c.setPattern)
-		benchMsg2 := fmt.Sprintf("RegexMatch,nSeries=%d,pattern=\"%s\"", c.numSeries, c.regexPattern)
-		b.Run(benchMsg1, func(b *testing.B) {
+		benchMsg := fmt.Sprintf("nSeries=%d,pattern=\"%s\"", c.numSeries, c.pattern)
+		b.Run(benchMsg, func(b *testing.B) {
 			b.ResetTimer()
 			b.ReportAllocs()
 			for n := 0; n < b.N; n++ {
-				_, err := que.Select(labels.NewMustRegexpMatcher("test", c.setPattern))
+				_, err := que.Select(labels.NewMustRegexpMatcher("test", c.pattern))
 				testutil.Ok(b, err)
 
 			}
 		})
-		b.Run(benchMsg2, func(b *testing.B) {
-			b.ResetTimer()
-			b.ReportAllocs()
-			for n := 0; n < b.N; n++ {
-				_, err := que.Select(labels.NewMustRegexpMatcher("test", c.regexPattern))
-				testutil.Ok(b, err)
-			}
-		})
 	}
 }
 

From b81e86b2e62ce08857afd8ba49382f3a4a1f3b4d Mon Sep 17 00:00:00 2001
From: naivewong <867245430@qq.com>
Date: Wed, 15 May 2019 16:07:24 +0800
Subject: [PATCH 10/19] update

Signed-off-by: naivewong <867245430@qq.com>
---
 querier_test.go | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/querier_test.go b/querier_test.go
index 18d23a58..3dd67b3c 100644
--- a/querier_test.go
+++ b/querier_test.go
@@ -1709,7 +1709,7 @@ func BenchmarkSetMatcher(b *testing.B) {
 		{
 			numBlocks:                   1,
 			numSeries:                   15,
-			numSamplesPerSeriesPerBlock: 10, 
+			numSamplesPerSeriesPerBlock: 10,
 			pattern:                     "^(?:1|2|3|4|5|6|7|8|9|10)$",
 		},
 		{
@@ -1721,7 +1721,7 @@ func BenchmarkSetMatcher(b *testing.B) {
 		{
 			numBlocks:                   20,
 			numSeries:                   1000,
-			numSamplesPerSeriesPerBlock: 10, 
+			numSamplesPerSeriesPerBlock: 10,
 			pattern:                     "^(?:1|2|3|4|5|6|7|8|9|10)$",
 		},
 	}
@@ -1739,14 +1739,14 @@ func BenchmarkSetMatcher(b *testing.B) {
 			generatedSeries []Series
 		)
 		for i := int64(0); i < int64(c.numBlocks); i++ {
-			mint := i*int64(c.numSamplesPerSeriesPerBlock)
+			mint := i * int64(c.numSamplesPerSeriesPerBlock)
 			maxt := mint + int64(c.numSamplesPerSeriesPerBlock) - 1
 			if len(prefilledLabels) == 0 {
 				generatedSeries = make([]Series, c.numSeries)
 				for i := 0; i < c.numSeries; i++ {
 					lbls := make(map[string]string, 10)
 					// The first label pair is {"test", "i%50"} which is for benchmarking set matcher.
-					lbls["test"] = strconv.Itoa(i%50)
+					lbls["test"] = strconv.Itoa(i % 50)
 					for len(lbls) < 10 {
 						lbls[randString()] = randString()
 					}

From 0f88eed28e9565e22e103d62002c1ef9afa352ff Mon Sep 17 00:00:00 2001
From: naivewong <867245430@qq.com>
Date: Wed, 15 May 2019 20:25:22 +0800
Subject: [PATCH 11/19] update benchmark

Signed-off-by: naivewong <867245430@qq.com>
---
 querier_test.go | 31 ++++++++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/querier_test.go b/querier_test.go
index 3dd67b3c..5fb43194 100644
--- a/querier_test.go
+++ b/querier_test.go
@@ -1700,11 +1700,13 @@ func BenchmarkSetMatcher(b *testing.B) {
 		numSamplesPerSeriesPerBlock int
 		pattern                     string
 	}{
+		// The first three cases are to find out whether the set
+		// matcher is always faster than regex matcher.
 		{
 			numBlocks:                   1,
-			numSeries:                   15,
+			numSeries:                   1,
 			numSamplesPerSeriesPerBlock: 10,
-			pattern:                     "^(?:1|2|3)$",
+			pattern:                     "^(?:1|2|3|4|5|6|7|8|9|10)$",
 		},
 		{
 			numBlocks:                   1,
@@ -1712,6 +1714,13 @@ func BenchmarkSetMatcher(b *testing.B) {
 			numSamplesPerSeriesPerBlock: 10,
 			pattern:                     "^(?:1|2|3|4|5|6|7|8|9|10)$",
 		},
+		{
+			numBlocks:                   1,
+			numSeries:                   15,
+			numSamplesPerSeriesPerBlock: 10,
+			pattern:                     "^(?:1|2|3)$",
+		},
+		// Big data sizes benchmarks.
 		{
 			numBlocks:                   20,
 			numSeries:                   1000,
@@ -1724,6 +1733,18 @@ func BenchmarkSetMatcher(b *testing.B) {
 			numSamplesPerSeriesPerBlock: 10,
 			pattern:                     "^(?:1|2|3|4|5|6|7|8|9|10)$",
 		},
+		{
+			numBlocks:                   1,
+			numSeries:                   100000,
+			numSamplesPerSeriesPerBlock: 10,
+			pattern:                     "^(?:1|2|3|4|5|6|7|8|9|10)$",
+		},
+		{
+			numBlocks:                   1,
+			numSeries:                   500000,
+			numSamplesPerSeriesPerBlock: 10,
+			pattern:                     "^(?:1|2|3|4|5|6|7|8|9|10)$",
+		},
 	}
 
 	for _, c := range cases {
@@ -1745,8 +1766,8 @@ func BenchmarkSetMatcher(b *testing.B) {
 				generatedSeries = make([]Series, c.numSeries)
 				for i := 0; i < c.numSeries; i++ {
 					lbls := make(map[string]string, 10)
-					// The first label pair is {"test", "i%50"} which is for benchmarking set matcher.
-					lbls["test"] = strconv.Itoa(i % 50)
+					// The first label pair is {"test", "i%100"} which is for benchmarking set matcher.
+					lbls["test"] = strconv.Itoa(i % 100)
 					for len(lbls) < 10 {
 						lbls[randString()] = randString()
 					}
@@ -1778,7 +1799,7 @@ func BenchmarkSetMatcher(b *testing.B) {
 		}
 		defer que.Close()
 
-		benchMsg := fmt.Sprintf("nSeries=%d,pattern=\"%s\"", c.numSeries, c.pattern)
+		benchMsg := fmt.Sprintf("nSeries=%d,nBlocks=%d,pattern=\"%s\"", c.numSeries, c.numBlocks, c.pattern)
 		b.Run(benchMsg, func(b *testing.B) {
 			b.ResetTimer()
 			b.ReportAllocs()

From 81cb0282e5c9ebad52153a8b98f02014afb68f63 Mon Sep 17 00:00:00 2001
From: naivewong <867245430@qq.com>
Date: Wed, 15 May 2019 21:03:09 +0800
Subject: [PATCH 12/19] update benchmark

Signed-off-by: naivewong <867245430@qq.com>
---
 querier_test.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/querier_test.go b/querier_test.go
index 5fb43194..4183cd66 100644
--- a/querier_test.go
+++ b/querier_test.go
@@ -1745,6 +1745,12 @@ func BenchmarkSetMatcher(b *testing.B) {
 			numSamplesPerSeriesPerBlock: 10,
 			pattern:                     "^(?:1|2|3|4|5|6|7|8|9|10)$",
 		},
+		{
+			numBlocks:                   10,
+			numSeries:                   500000,
+			numSamplesPerSeriesPerBlock: 10,
+			pattern:                     "^(?:1|2|3|4|5|6|7|8|9|10)$",
+		},
 	}
 
 	for _, c := range cases {

From 954df56feb971bc1a9ec1ae36b38d54153de9879 Mon Sep 17 00:00:00 2001
From: naivewong <867245430@qq.com>
Date: Thu, 16 May 2019 11:40:03 +0800
Subject: [PATCH 13/19] update benchmark

Signed-off-by: naivewong <867245430@qq.com>
---
 querier_test.go | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/querier_test.go b/querier_test.go
index 4183cd66..5d070125 100644
--- a/querier_test.go
+++ b/querier_test.go
@@ -1698,6 +1698,7 @@ func BenchmarkSetMatcher(b *testing.B) {
 		numBlocks                   int
 		numSeries                   int
 		numSamplesPerSeriesPerBlock int
+		cardinality                 int
 		pattern                     string
 	}{
 		// The first three cases are to find out whether the set
@@ -1706,18 +1707,21 @@ func BenchmarkSetMatcher(b *testing.B) {
 			numBlocks:                   1,
 			numSeries:                   1,
 			numSamplesPerSeriesPerBlock: 10,
+			cardinality:                 100,
 			pattern:                     "^(?:1|2|3|4|5|6|7|8|9|10)$",
 		},
 		{
 			numBlocks:                   1,
 			numSeries:                   15,
 			numSamplesPerSeriesPerBlock: 10,
+			cardinality:                 100,
 			pattern:                     "^(?:1|2|3|4|5|6|7|8|9|10)$",
 		},
 		{
 			numBlocks:                   1,
 			numSeries:                   15,
 			numSamplesPerSeriesPerBlock: 10,
+			cardinality:                 100,
 			pattern:                     "^(?:1|2|3)$",
 		},
 		// Big data sizes benchmarks.
@@ -1725,30 +1729,43 @@ func BenchmarkSetMatcher(b *testing.B) {
 			numBlocks:                   20,
 			numSeries:                   1000,
 			numSamplesPerSeriesPerBlock: 10,
+			cardinality:                 100,
 			pattern:                     "^(?:1|2|3)$",
 		},
 		{
 			numBlocks:                   20,
 			numSeries:                   1000,
 			numSamplesPerSeriesPerBlock: 10,
+			cardinality:                 100,
 			pattern:                     "^(?:1|2|3|4|5|6|7|8|9|10)$",
 		},
+		// Increase cardinality.
 		{
 			numBlocks:                   1,
 			numSeries:                   100000,
 			numSamplesPerSeriesPerBlock: 10,
+			cardinality:                 100000,
 			pattern:                     "^(?:1|2|3|4|5|6|7|8|9|10)$",
 		},
 		{
 			numBlocks:                   1,
 			numSeries:                   500000,
 			numSamplesPerSeriesPerBlock: 10,
+			cardinality:                 500000,
 			pattern:                     "^(?:1|2|3|4|5|6|7|8|9|10)$",
 		},
 		{
 			numBlocks:                   10,
 			numSeries:                   500000,
 			numSamplesPerSeriesPerBlock: 10,
+			cardinality:                 500000,
+			pattern:                     "^(?:1|2|3|4|5|6|7|8|9|10)$",
+		},
+		{
+			numBlocks:                   1,
+			numSeries:                   1000000,
+			numSamplesPerSeriesPerBlock: 10,
+			cardinality:                 1000000,
 			pattern:                     "^(?:1|2|3|4|5|6|7|8|9|10)$",
 		},
 	}
@@ -1772,8 +1789,8 @@ func BenchmarkSetMatcher(b *testing.B) {
 				generatedSeries = make([]Series, c.numSeries)
 				for i := 0; i < c.numSeries; i++ {
 					lbls := make(map[string]string, 10)
-					// The first label pair is {"test", "i%100"} which is for benchmarking set matcher.
-					lbls["test"] = strconv.Itoa(i % 100)
+					// The first label pair is {"test", "i%cardinality"} which is for benchmarking set matcher.
+					lbls["test"] = strconv.Itoa(i % c.cardinality)
 					for len(lbls) < 10 {
 						lbls[randString()] = randString()
 					}

From c929d7ad0243b9a9faaea9de7f7a270cd3536466 Mon Sep 17 00:00:00 2001
From: naivewong <867245430@qq.com>
Date: Thu, 16 May 2019 11:46:07 +0800
Subject: [PATCH 14/19] update

Signed-off-by: naivewong <867245430@qq.com>
---
 querier_test.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/querier_test.go b/querier_test.go
index 5d070125..287ea04d 100644
--- a/querier_test.go
+++ b/querier_test.go
@@ -1822,7 +1822,7 @@ func BenchmarkSetMatcher(b *testing.B) {
 		}
 		defer que.Close()
 
-		benchMsg := fmt.Sprintf("nSeries=%d,nBlocks=%d,pattern=\"%s\"", c.numSeries, c.numBlocks, c.pattern)
+		benchMsg := fmt.Sprintf("nSeries=%d,nBlocks=%d,cardinality=%d,pattern=\"%s\"", c.numSeries, c.numBlocks, c.cardinality, c.pattern)
 		b.Run(benchMsg, func(b *testing.B) {
 			b.ResetTimer()
 			b.ReportAllocs()

From 959158eb3ad63e7f2591736d7b2a26e80adbf804 Mon Sep 17 00:00:00 2001
From: naivewong <867245430@qq.com>
Date: Thu, 16 May 2019 17:07:05 +0800
Subject: [PATCH 15/19] update

Signed-off-by: naivewong <867245430@qq.com>
---
 querier_test.go | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/querier_test.go b/querier_test.go
index 287ea04d..25f32165 100644
--- a/querier_test.go
+++ b/querier_test.go
@@ -1791,8 +1791,10 @@ func BenchmarkSetMatcher(b *testing.B) {
 					lbls := make(map[string]string, 10)
 					// The first label pair is {"test", "i%cardinality"} which is for benchmarking set matcher.
 					lbls["test"] = strconv.Itoa(i % c.cardinality)
+					j := 1
 					for len(lbls) < 10 {
-						lbls[randString()] = randString()
+						lbls["labelName"+strconv.Itoa(j)] = "labelValue" + strconv.Itoa(j)
+						j += 1
 					}
 					samples := make([]tsdbutil.Sample, 0, maxt-mint+1)
 					for t := mint; t <= maxt; t++ {

From 591ae7caab693050638bf4936427dff591ac85c6 Mon Sep 17 00:00:00 2001
From: naivewong <867245430@qq.com>
Date: Thu, 16 May 2019 17:54:48 +0800
Subject: [PATCH 16/19] update

Signed-off-by: naivewong <867245430@qq.com>
---
 querier.go      | 36 +++++++++++++++++++-----------------
 querier_test.go |  4 ++--
 2 files changed, 21 insertions(+), 19 deletions(-)

diff --git a/querier.go b/querier.go
index f6f7f658..253102b0 100644
--- a/querier.go
+++ b/querier.go
@@ -267,49 +267,49 @@ func (q *blockQuerier) Close() error {
 	return merr.Err()
 }
 
-// Bitmap used by func special to check whether a character needs to be escaped.
-var specialBytes [16]byte
+// Bitmap used by func isRegexMetaCharacter to check whether a character needs to be escaped.
+var regexMetaCharacterBytes [16]byte
 
-// special reports whether byte b needs to be escaped.
-func special(b byte) bool {
-	return b < utf8.RuneSelf && specialBytes[b%16]&(1<<(b/16)) != 0
+// isRegexMetaCharacter reports whether byte b needs to be escaped.
+func isRegexMetaCharacter(b byte) bool {
+	return b < utf8.RuneSelf && regexMetaCharacterBytes[b%16]&(1<<(b/16)) != 0
 }
 
 func init() {
 	for _, b := range []byte(`.+*?()|[]{}^$`) {
-		specialBytes[b%16] |= 1 << (b / 16)
+		regexMetaCharacterBytes[b%16] |= 1 << (b / 16)
 	}
 }
 
 func findSetMatches(pattern string) []string {
 	// Return empty matches if the wrapper from Prometheus is missing.
 	if len(pattern) < 6 || pattern[:4] != "^(?:" || pattern[len(pattern)-2:] != ")$" {
-		return []string{}
+		return nil
 	}
 	escaped := false
 	sets := []*strings.Builder{&strings.Builder{}}
 	for i := 4; i < len(pattern)-2; i++ {
 		if escaped {
-			// Add the escaped special character to the sets.
-			if special(pattern[i]) {
+			switch {
+			case isRegexMetaCharacter(pattern[i]):
 				sets[len(sets)-1].WriteByte(pattern[i])
-			} else if pattern[i] == '\\' {
+			case pattern[i] == '\\':
 				sets[len(sets)-1].WriteByte('\\')
-			} else {
-				return []string{}
+			default:
+				return nil
 			}
 			escaped = false
 		} else {
-			// Return empty sets when there are special characters excluding '|'.
-			if special(pattern[i]) {
+			switch {
+			case isRegexMetaCharacter(pattern[i]):
 				if pattern[i] == '|' {
 					sets = append(sets, &strings.Builder{})
 				} else {
-					return []string{}
+					return nil
 				}
-			} else if pattern[i] == '\\' {
+			case pattern[i] == '\\':
 				escaped = true
-			} else {
+			default:
 				sets[len(sets)-1].WriteByte(pattern[i])
 			}
 		}
@@ -481,6 +481,8 @@ func postingsForSetMatcher(ix IndexReader, name string, matches []string) (index
 	for _, match := range matches {
 		if it, err := ix.Postings(name, match); err == nil {
 			its = append(its, it)
+		} else {
+			return nil, err
 		}
 	}
 	return index.Merge(its...), nil
diff --git a/querier_test.go b/querier_test.go
index 25f32165..af94a77e 100644
--- a/querier_test.go
+++ b/querier_test.go
@@ -1864,12 +1864,12 @@ func TestFindSetMatches(t *testing.T) {
 		// Simple sets containing special characters without escaping.
 		{
 			pattern: "^(?:fo.o|bar?|^baz)$",
-			exp:     []string{},
+			exp:     nil,
 		},
 		// Missing wrapper.
 		{
 			pattern: "foo|bar|baz",
-			exp:     []string{},
+			exp:     nil,
 		},
 	}
 

From 2749e565529f2951dab594fa51b415213395bb3f Mon Sep 17 00:00:00 2001
From: naivewong <867245430@qq.com>
Date: Fri, 17 May 2019 11:08:56 +0800
Subject: [PATCH 17/19] update

Signed-off-by: naivewong <867245430@qq.com>
---
 querier_test.go | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/querier_test.go b/querier_test.go
index af94a77e..1b0ba271 100644
--- a/querier_test.go
+++ b/querier_test.go
@@ -2107,6 +2107,15 @@ func TestPostingsForMatchers(t *testing.T) {
 				labels.FromStrings("n", "2.5"),
 			},
 		},
+		// Empty value.
+		{
+			matchers: []labels.Matcher{labels.NewMustRegexpMatcher("i", "^(?:c||d)$")},
+			exp: []labels.Labels{
+				labels.FromStrings("n", "1"),
+				labels.FromStrings("n", "2"),
+				labels.FromStrings("n", "2.5"),
+			},
+		},
 	}
 
 	ir, err := h.Index()

From d30f3a2e797740be349a52b146aea7983aaf3a09 Mon Sep 17 00:00:00 2001
From: naivewong <867245430@qq.com>
Date: Fri, 17 May 2019 22:25:01 +0800
Subject: [PATCH 18/19] use genSeries from #467

Signed-off-by: naivewong <867245430@qq.com>
---
 block_test.go   | 39 +++++++++------------------------------
 querier_test.go |  1 -
 2 files changed, 9 insertions(+), 31 deletions(-)

diff --git a/block_test.go b/block_test.go
index bdfd58fb..3ae2ec24 100644
--- a/block_test.go
+++ b/block_test.go
@@ -21,6 +21,7 @@ import (
 	"math/rand"
 	"os"
 	"path/filepath"
+	"strconv"
 	"testing"
 
 	"github.com/go-kit/kit/log"
@@ -184,6 +185,11 @@ func createBlock(tb testing.TB, dir string, series []Series) string {
 	return filepath.Join(dir, ulid.String())
 }
 
+const (
+	defaultLabelName  = "labelName"
+	defaultLabelValue = "labelValue"
+)
+
 // genSeries generates series with a given number of labels and values.
 func genSeries(totalSeries, labelCount int, mint, maxt int64) []Series {
 	if totalSeries == 0 || labelCount == 0 {
@@ -193,8 +199,9 @@ func genSeries(totalSeries, labelCount int, mint, maxt int64) []Series {
 	series := make([]Series, totalSeries)
 	for i := 0; i < totalSeries; i++ {
 		lbls := make(map[string]string, labelCount)
-		for len(lbls) < labelCount {
-			lbls[randString()] = randString()
+		lbls[defaultLabelName] = strconv.Itoa(i)
+		for j := 1; len(lbls) < labelCount; j++ {
+			lbls[defaultLabelName+strconv.Itoa(j)] = defaultLabelValue + strconv.Itoa(j)
 		}
 		samples := make([]tsdbutil.Sample, 0, maxt-mint+1)
 		for t := mint; t <= maxt; t++ {
@@ -224,31 +231,3 @@ func populateSeries(lbls []map[string]string, mint, maxt int64) []Series {
 	}
 	return series
 }
-
-const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
-const (
-	letterIdxBits = 6                    // 6 bits to represent a letter index
-	letterIdxMask = 1<<letterIdxBits - 1 // All 1-bits, as many as letterIdxBits
-	letterIdxMax  = 63 / letterIdxBits   // # of letter indices fitting in 63 bits
-)
-
-// randString generates random string.
-func randString() string {
-	maxLength := int32(50)
-	length := rand.Int31n(maxLength)
-	b := make([]byte, length+1)
-	// A rand.Int63() generates 63 random bits, enough for letterIdxMax characters!
-	for i, cache, remain := length, rand.Int63(), letterIdxMax; i >= 0; {
-		if remain == 0 {
-			cache, remain = rand.Int63(), letterIdxMax
-		}
-		if idx := int(cache & letterIdxMask); idx < len(letterBytes) {
-			b[i] = letterBytes[idx]
-			i--
-		}
-		cache >>= letterIdxBits
-		remain--
-	}
-
-	return string(b)
-}
diff --git a/querier_test.go b/querier_test.go
index 1b0ba271..ff27cdc1 100644
--- a/querier_test.go
+++ b/querier_test.go
@@ -21,7 +21,6 @@ import (
 	"os"
 	"path/filepath"
 	"sort"
-	"strconv"
 	"testing"
 
 	"github.com/pkg/errors"

From 6049a19ad8bac905422d5ecf960459c768410695 Mon Sep 17 00:00:00 2001
From: naivewong <867245430@qq.com>
Date: Fri, 17 May 2019 22:35:18 +0800
Subject: [PATCH 19/19] update

Signed-off-by: naivewong <867245430@qq.com>
---
 querier_test.go | 17 +----------------
 1 file changed, 1 insertion(+), 16 deletions(-)

diff --git a/querier_test.go b/querier_test.go
index ff27cdc1..dfbc6a75 100644
--- a/querier_test.go
+++ b/querier_test.go
@@ -1785,22 +1785,7 @@ func BenchmarkSetMatcher(b *testing.B) {
 			mint := i * int64(c.numSamplesPerSeriesPerBlock)
 			maxt := mint + int64(c.numSamplesPerSeriesPerBlock) - 1
 			if len(prefilledLabels) == 0 {
-				generatedSeries = make([]Series, c.numSeries)
-				for i := 0; i < c.numSeries; i++ {
-					lbls := make(map[string]string, 10)
-					// The first label pair is {"test", "i%cardinality"} which is for benchmarking set matcher.
-					lbls["test"] = strconv.Itoa(i % c.cardinality)
-					j := 1
-					for len(lbls) < 10 {
-						lbls["labelName"+strconv.Itoa(j)] = "labelValue" + strconv.Itoa(j)
-						j += 1
-					}
-					samples := make([]tsdbutil.Sample, 0, maxt-mint+1)
-					for t := mint; t <= maxt; t++ {
-						samples = append(samples, sample{t: t, v: rand.Float64()})
-					}
-					generatedSeries[i] = newSeries(lbls, samples)
-				}
+				generatedSeries = genSeries(c.numSeries, 10, mint, maxt)
 				for _, s := range generatedSeries {
 					prefilledLabels = append(prefilledLabels, s.Labels().Map())
 				}