ddl: fix adding multi-value index (#51884)

pkg/ddl/index.go

@@ -1782,6 +1782,7 @@ func writeChunkToLocal(
 	maxIdxColCnt := maxIndexColumnCount(indexes)
 	idxDataBuf := make([]types.Datum, maxIdxColCnt)
 	handleDataBuf := make([]types.Datum, len(c.HandleOutputOffsets))
+	var restoreDataBuf []types.Datum
 	count := 0
 	var lastHandle kv.Handle
 
@@ -1795,8 +1796,24 @@ func writeChunkToLocal(
 			unlock()
 		}
 	}()
+	needRestoreForIndexes := make([]bool, len(indexes))
+	restore := false
+	for i, index := range indexes {
+		needRestore := tables.NeedRestoredData(index.Meta().Columns, c.TableInfo.Columns)
+		needRestoreForIndexes[i] = needRestore
+		restore = restore || needRestore
+	}
+	if restore {
+		restoreDataBuf = make([]types.Datum, len(c.HandleOutputOffsets))
+	}
 	for row := iter.Begin(); row != iter.End(); row = iter.Next() {
 		handleDataBuf := extractDatumByOffsets(row, c.HandleOutputOffsets, c.ExprColumnInfos, handleDataBuf)
+		if restore {
+			// restoreDataBuf should not truncate index values.
+			for i, datum := range handleDataBuf {
+				restoreDataBuf[i] = *datum.Clone()
+			}
+		}
 		h, err := buildHandle(handleDataBuf, c.TableInfo, c.PrimaryKeyInfo, sCtx)
 		if err != nil {
 			return 0, nil, errors.Trace(err)
@@ -1806,7 +1823,10 @@ func writeChunkToLocal(
 			idxDataBuf = extractDatumByOffsets(
 				row, copCtx.IndexColumnOutputOffsets(idxID), c.ExprColumnInfos, idxDataBuf)
 			idxData := idxDataBuf[:len(index.Meta().Columns)]
-			rsData := getRestoreData(c.TableInfo, copCtx.IndexInfo(idxID), c.PrimaryKeyInfo, handleDataBuf)
+			var rsData []types.Datum
+			if needRestoreForIndexes[i] {
+				rsData = getRestoreData(c.TableInfo, copCtx.IndexInfo(idxID), c.PrimaryKeyInfo, restoreDataBuf)
+			}
 			err = writeOneKVToLocal(ctx, writers[i], index, sCtx, writeBufs, idxData, rsData, h)
 			if err != nil {
 				return 0, nil, errors.Trace(err)

tests/realtikvtest/addindextest/add_index_test.go

@@ -112,3 +112,26 @@ func TestAddForeignKeyWithAutoCreateIndex(t *testing.T) {
 	tk.MustExec("update employee set pid=id-1 where id>1 and pid is null")
 	tk.MustExec("alter table employee add foreign key fk_1(pid) references employee(id)")
 }
+
+func TestIssue51162(t *testing.T) {
+	store := realtikvtest.CreateMockStoreAndSetup(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec("set global tidb_enable_fast_table_check=0")
+	tk.MustExec(`CREATE TABLE tl (
+	 col_42 json NOT NULL,
+	 col_43 tinyint(1) DEFAULT NULL,
+	 col_44 char(168) CHARACTER SET gbk COLLATE gbk_bin DEFAULT NULL,
+	 col_45 json DEFAULT NULL,
+	 col_46 text COLLATE utf8mb4_unicode_ci NOT NULL,
+	 col_47 char(43) COLLATE utf8mb4_unicode_ci NOT NULL DEFAULT 'xW2YNb99pse4)',
+	 col_48 time NOT NULL DEFAULT '12:31:25',
+	 PRIMARY KEY (col_47,col_46(2)) /*T![clustered_index] CLUSTERED */
+	  ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;`)
+
+	tk.MustExec(`INSERT INTO tl VALUES
+	('[\"1\"]',0,'1','[1]','Wxup81','1','10:14:20');`)
+
+	tk.MustExec("alter table tl add index idx_16(`col_48`,(cast(`col_45` as signed array)),`col_46`(5));")
+	tk.MustExec("admin check table tl")
+}