ddl: use the correct timezone to encode record for adding index

ddl/index.go

@@ -1666,10 +1666,22 @@
 	return cnt, nextKey, nil
 }
 
+// setUTCTimezone sets the timezone to UTC for the session variable.
+// This is because the time value in coprocessor reader is in UTC.
+func setUTCTimezone(vars *stmtctx.StatementContext) (restore func()) {
+	originTZ := vars.TimeZone
+	vars.TimeZone = time.UTC
+	return func() {
+		vars.TimeZone = originTZ
+	}
+}
+
 func writeChunkToLocal(writer ingest.Writer,
 	index table.Index, copCtx *copContext, vars *variable.SessionVars,
 	copChunk *chunk.Chunk) (int, kv.Handle, error) {
 	sCtx, writeBufs := vars.StmtCtx, vars.GetWriteStmtBufs()
+	restore := setUTCTimezone(sCtx)
+	defer restore()
 	iter := chunk.NewIterator4Chunk(copChunk)
 	idxDataBuf := make([]types.Datum, len(copCtx.idxColOutputOffsets))
 	handleDataBuf := make([]types.Datum, len(copCtx.handleOutputOffsets))

ddl/ingest/BUILD.bazel

@@ -65,7 +65,7 @@ go_test(
     embed = [":ingest"],
     flaky = True,
     race = "on",
-    shard_count = 14,
+    shard_count = 15,
     deps = [
         "//config",
         "//ddl",

ddl/ingest/integration_test.go

@@ -323,3 +323,16 @@ func TestAddIndexIngestRecoverPartition(t *testing.T) {
 	tk.MustExec("alter table t add index idx(b);")
 	tk.MustExec("admin check table t;")
 }
+
+func TestAddIndexIngestTimezone(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test;")
+	defer injectMockBackendMgr(t, store)()
+
+	tk.MustExec("SET time_zone = '-06:00';")
+	tk.MustExec("create table t (`src` varchar(48),`t` timestamp,`timezone` varchar(100));")
+	tk.MustExec("insert into t values('2000-07-29 23:15:30 -0600','2000-07-29 23:15:30 -0600','-6:00');")
+	tk.MustExec("alter table t add index idx(t);")
+	tk.MustExec("admin check table t;")
+}