rm unused replaceAll for \Z

Author: elianddb

enginetest/queries/alter_table_queries.go

@@ -1047,6 +1047,21 @@ var AlterTableScripts = []ScriptTest{
 			},
 		},
 	},
+	{
+		Name: "alter table supports non-escaped \\Z",
+		SetUpScript: []string{
+			"create table t (i int);",
+			`alter table t modify column i int comment "ctrlz \\Z \\Z"`,
+		},
+		Assertions: []ScriptTestAssertion{
+			{
+				Query: "show create table t",
+				Expected: []sql.Row{{"t", "CREATE TABLE `t` (\n" +
+					"  `i` int COMMENT 'ctrlz \\Z \\Z'\n" +
+					") ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin"}},
+			},
+		},
+	},
 }
 
 var RenameTableScripts = []ScriptTest{

enginetest/queries/create_table_queries.go

@@ -58,6 +58,12 @@ var CreateTableQueries = []WriteQueryTest{
 		SelectQuery:         "SHOW CREATE TABLE tableWithComment",
 		ExpectedSelect:      []sql.Row{{"tableWithComment", "CREATE TABLE `tableWithComment` (\n  `pk` int\n) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin COMMENT='newline \\n | return \\r | backslash \\\\ | NUL \\0 x00 | ctrlz \x1A x1A'"}},
 	},
+	{
+		WriteQuery:          `create table tableWithComment (pk int) COMMENT "ctrlz \Z \x1A \\Z \\\Z"`,
+		ExpectedWriteResult: []sql.Row{{types.NewOkResult(0)}},
+		SelectQuery:         "SHOW CREATE TABLE tableWithComment",
+		ExpectedSelect:      []sql.Row{{"tableWithComment", "CREATE TABLE `tableWithComment` (\n  `pk` int\n) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin COMMENT='ctrlz \x1A x1A \\\\Z \\\\\x1A'"}},
+	},
 	{
 		WriteQuery:          `create table tableWithColumnComment (pk int COMMENT "'")`,
 		ExpectedWriteResult: []sql.Row{{types.NewOkResult(0)}},

sql/parser.go

@@ -138,7 +138,6 @@ func EscapeSpecialCharactersInComment(comment string) string {
 	commentString := comment
 	commentString = strings.ReplaceAll(commentString, "'", "''")
 	commentString = strings.ReplaceAll(commentString, "\\", "\\\\")
-	commentString = strings.ReplaceAll(commentString, "\\Z", "\x1A") // MYSQL handles \\ first, then \Z
 	commentString = strings.ReplaceAll(commentString, "\"", "\\\"")
 	commentString = strings.ReplaceAll(commentString, "\n", "\\n")
 	commentString = strings.ReplaceAll(commentString, "\r", "\\r")