cherry pick pingcap#35475 to release-6.0

Signed-off-by: ti-srebot <ti-srebot@pingcap.com>

expression/integration_serial_test.go

@@ -815,9 +815,16 @@ func TestCollateStringFunction(t *testing.T) {
 	tk.MustQuery("select locate('S', 'a' collate utf8mb4_general_ci);").Check(testkit.Rows("0"))
 	// MySQL return 0 here, I believe it is a bug in MySQL since 'ß' == 's' under utf8mb4_general_ci collation.
 	tk.MustQuery("select locate('ß', 's' collate utf8mb4_general_ci);").Check(testkit.Rows("1"))
+	tk.MustQuery("select locate('world', 'hello world' collate utf8mb4_general_ci);").Check(testkit.Rows("7"))
+	tk.MustQuery("select locate(' ', 'hello world' collate utf8mb4_general_ci);").Check(testkit.Rows("6"))
+	tk.MustQuery("select locate('  ', 'hello world' collate utf8mb4_general_ci);").Check(testkit.Rows("0"))
+
 	tk.MustQuery("select locate('S', 's' collate utf8mb4_unicode_ci);").Check(testkit.Rows("1"))
 	tk.MustQuery("select locate('S', 'a' collate utf8mb4_unicode_ci);").Check(testkit.Rows("0"))
 	tk.MustQuery("select locate('ß', 'ss' collate utf8mb4_unicode_ci);").Check(testkit.Rows("1"))
+	tk.MustQuery("select locate('world', 'hello world' collate utf8mb4_unicode_ci);").Check(testkit.Rows("7"))
+	tk.MustQuery("select locate(' ', 'hello world' collate utf8mb4_unicode_ci);").Check(testkit.Rows("6"))
+	tk.MustQuery("select locate('  ', 'hello world' collate utf8mb4_unicode_ci);").Check(testkit.Rows("0"))
 
 	tk.MustExec("truncate table t1;")
 	tk.MustExec("insert into t1 (a) values (1);")

expression/util.go

@@ -547,8 +547,8 @@ func SubstituteCorCol2Constant(expr Expression) (Expression, error) {
 
 func locateStringWithCollation(str, substr, coll string) int64 {
 	collator := collate.GetCollator(coll)
-	strKey := collator.Key(str)
-	subStrKey := collator.Key(substr)
+	strKey := collator.KeyWithoutTrimRightSpace(str)
+	subStrKey := collator.KeyWithoutTrimRightSpace(substr)
 
 	index := bytes.Index(strKey, subStrKey)
 	if index == -1 || index == 0 {
@@ -560,8 +560,8 @@ func locateStringWithCollation(str, substr, coll string) int64 {
 	for {
 		r, size := utf8.DecodeRuneInString(str)
 		count += 1
-		index -= len(collator.Key(string(r)))
-		if index == 0 {
+		index -= len(collator.KeyWithoutTrimRightSpace(string(r)))
+		if index <= 0 {
 			return count + 1
 		}
 		str = str[size:]

util/collate/bin.go

@@ -33,6 +33,11 @@ func (bc *binCollator) Key(str string) []byte {
 	return []byte(str)
 }
 
+// KeyWithoutTrimRightSpace implement Collator interface.
+func (bc *binCollator) KeyWithoutTrimRightSpace(str string) []byte {
+	return []byte(str)
+}
+
 // Pattern implements Collator interface.
 func (bc *binCollator) Pattern() WildcardPattern {
 	return &binPattern{}
@@ -49,6 +54,11 @@ func (bpc *binPaddingCollator) Key(str string) []byte {
 	return []byte(truncateTailingSpace(str))
 }
 
+// KeyWithoutTrimRightSpace implement Collator interface.
+func (bpc *binPaddingCollator) KeyWithoutTrimRightSpace(str string) []byte {
+	return []byte(str)
+}
+
 // Pattern implements Collator interface.
 // Notice that trailing spaces are significant.
 func (bpc *binPaddingCollator) Pattern() WildcardPattern {

util/collate/collate.go

@@ -66,6 +66,8 @@ type Collator interface {
 	Compare(a, b string) int
 	// Key returns the collate key for str. If the collation is padding, make sure the PadLen >= len(rune[]str) in opt.
 	Key(str string) []byte
+	// KeyWithoutTrimRightSpace returns the collate key for str. The difference with Key is str will not be trimed.
+	KeyWithoutTrimRightSpace(str string) []byte
 	// Pattern get a collation-aware WildcardPattern.
 	Pattern() WildcardPattern
 }

util/collate/gbk_bin.go

@@ -58,7 +58,11 @@ func (g *gbkBinCollator) Compare(a, b string) int {
 
 // Key implement Collator interface.
 func (g *gbkBinCollator) Key(str string) []byte {
-	str = truncateTailingSpace(str)
+	return g.KeyWithoutTrimRightSpace(truncateTailingSpace(str))
+}
+
+// KeyWithoutTrimRightSpace implement Collator interface.
+func (g *gbkBinCollator) KeyWithoutTrimRightSpace(str string) []byte {
 	buf := make([]byte, 0, len(str))
 	for len(str) > 0 {
 		l := runeLen(str[0])

util/collate/gbk_chinese_ci.go

@@ -40,7 +40,11 @@ func (g *gbkChineseCICollator) Compare(a, b string) int {
 
 // Key implements Collator interface.
 func (g *gbkChineseCICollator) Key(str string) []byte {
-	str = truncateTailingSpace(str)
+	return g.KeyWithoutTrimRightSpace(truncateTailingSpace(str))
+}
+
+// KeyWithoutTrimRightSpace implement Collator interface.
+func (g *gbkChineseCICollator) KeyWithoutTrimRightSpace(str string) []byte {
 	buf := make([]byte, 0, len(str)*2)
 	i := 0
 	r := rune(0)

util/collate/general_ci.go

@@ -41,7 +41,11 @@ func (gc *generalCICollator) Compare(a, b string) int {
 
 // Key implements Collator interface.
 func (gc *generalCICollator) Key(str string) []byte {
-	str = truncateTailingSpace(str)
+	return gc.KeyWithoutTrimRightSpace(truncateTailingSpace(str))
+}
+
+// KeyWithoutTrimRightSpace implements Collator interface.
+func (gc *generalCICollator) KeyWithoutTrimRightSpace(str string) []byte {
 	buf := make([]byte, 0, len(str))
 	i := 0
 	r := rune(0)

util/collate/pinyin_tidb_as_cs.go

@@ -28,6 +28,11 @@ func (py *zhPinyinTiDBASCSCollator) Key(str string) []byte {
 	panic("implement me")
 }
 
+// Collator interface, no implements now.
+func (py *zhPinyinTiDBASCSCollator) KeyWithoutTrimRightSpace(str string) []byte {
+	panic("implement me")
+}
+
 // Collator interface, no implements now.
 func (py *zhPinyinTiDBASCSCollator) Pattern() WildcardPattern {
 	panic("implement me")

util/collate/unicode_ci.go

@@ -85,7 +85,11 @@ func (uc *unicodeCICollator) Compare(a, b string) int {
 
 // Key implements Collator interface.
 func (uc *unicodeCICollator) Key(str string) []byte {
-	str = truncateTailingSpace(str)
+	return uc.KeyWithoutTrimRightSpace(truncateTailingSpace(str))
+}
+
+// KeyWithoutTrimRightSpace implements Collator interface.
+func (uc *unicodeCICollator) KeyWithoutTrimRightSpace(str string) []byte {
 	buf := make([]byte, 0, len(str)*2)
 	r := rune(0)
 	si := 0                        // decode index of s