ddl: fix creating partition table with unique prefix index (#17196)

ddl/column.go

@@ -623,13 +623,13 @@ func generateOriginDefaultValue(col *model.ColumnInfo) (interface{}, error) {
 	return odValue, nil
 }
 
-func findColumnInIndexCols(c string, cols []*model.IndexColumn) bool {
+func findColumnInIndexCols(c string, cols []*model.IndexColumn) *model.IndexColumn {
 	for _, c1 := range cols {
 		if c == c1.Name.L {
-			return true
+			return c1
 		}
 	}
-	return false
+	return nil
 }
 
 func getColumnInfoByName(tbInfo *model.TableInfo, column string) *model.ColumnInfo {

ddl/db_partition_test.go

@@ -1216,6 +1216,22 @@ func (s *testIntegrationSuite5) TestPartitionUniqueKeyNeedAllFieldsInPf(c *C) {
                partition p2 values less than (11, 22)
         )`
 	tk.MustGetErrCode(sql11, tmysql.ErrUniqueKeyNeedAllFieldsInPf)
+
+	sql12 := `create table part12 (a varchar(20), b binary, unique index (a(5))) partition by range columns (a) (
+			partition p0 values less than ('aaaaa'),
+			partition p1 values less than ('bbbbb'),
+			partition p2 values less than ('ccccc'))`
+	tk.MustGetErrCode(sql12, tmysql.ErrUniqueKeyNeedAllFieldsInPf)
+	tk.MustExec(`create table part12 (a varchar(20), b binary) partition by range columns (a) (
+			partition p0 values less than ('aaaaa'),
+			partition p1 values less than ('bbbbb'),
+			partition p2 values less than ('ccccc'))`)
+	tk.MustGetErrCode("alter table part12 add unique index (a(5))", tmysql.ErrUniqueKeyNeedAllFieldsInPf)
+	sql13 := `create table part13 (a varchar(20), b varchar(10), unique index (a(5),b)) partition by range columns (b) (
+			partition p0 values less than ('aaaaa'),
+			partition p1 values less than ('bbbbb'),
+			partition p2 values less than ('ccccc'))`
+	tk.MustExec(sql13)
 }
 
 func (s *testIntegrationSuite2) TestPartitionDropPrimaryKey(c *C) {

ddl/partition.go

@@ -861,7 +861,13 @@ type stringSlice interface {
 func checkUniqueKeyIncludePartKey(partCols stringSlice, idxCols []*model.IndexColumn) bool {
 	for i := 0; i < partCols.Len(); i++ {
 		partCol := partCols.At(i)
-		if !findColumnInIndexCols(partCol, idxCols) {
+		idxCol := findColumnInIndexCols(partCol, idxCols)
+		if idxCol == nil {
+			// Partition column is not found in the index columns.
+			return false
+		}
+		if idxCol.Length > 0 {
+			// The partition column is found in the index columns, but the index column is a prefix index
 			return false
 		}
 	}