From d18cf71867ab1cb769948eb0956cefdac393c956 Mon Sep 17 00:00:00 2001
From: Hangjie Mo <mohangjie1995@gmail.com>
Date: Mon, 12 Dec 2022 12:11:16 +0800
Subject: [PATCH] ddl: fix unexpect fail when create expression index

---
 ddl/backfilling.go | 12 +++++++++++-
 ddl/column.go      |  4 ++--
 ddl/index.go       |  6 +++---
 3 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/ddl/backfilling.go b/ddl/backfilling.go
index f20e28f08b1f3..2c0ca5bb7919d 100644
--- a/ddl/backfilling.go
+++ b/ddl/backfilling.go
@@ -29,6 +29,7 @@ import (
 	ddlutil "github.com/pingcap/tidb/ddl/util"
 	"github.com/pingcap/tidb/expression"
 	"github.com/pingcap/tidb/kv"
+	"github.com/pingcap/tidb/meta"
 	"github.com/pingcap/tidb/metrics"
 	"github.com/pingcap/tidb/parser/model"
 	"github.com/pingcap/tidb/parser/terror"
@@ -805,12 +806,21 @@ func (b *backfillScheduler) Close() {
 //
 // The above operations are completed in a transaction.
 // Finally, update the concurrent processing of the total number of rows, and store the completed handle value.
-func (dc *ddlCtx) writePhysicalTableRecord(sessPool *sessionPool, t table.PhysicalTable, bfWorkerType backfillWorkerType, reorgInfo *reorgInfo) error {
+func (dc *ddlCtx) writePhysicalTableRecord(sess *session, sessPool *sessionPool, t table.PhysicalTable, bfWorkerType backfillWorkerType, reorgInfo *reorgInfo) error {
 	job := reorgInfo.Job
 	totalAddedCount := job.GetRowCount()
 
 	startKey, endKey := reorgInfo.StartKey, reorgInfo.EndKey
 	sessCtx := newContext(reorgInfo.d.store)
+	m, err := sess.Txn(true)
+	if err != nil {
+		return err
+	}
+	dbInfo, err := meta.NewMeta(m).GetDatabase(job.SchemaID)
+	if err != nil {
+		return err
+	}
+	sessCtx.GetSessionVars().CurrentDB = dbInfo.Name.O
 	decodeColMap, err := makeupDecodeColMap(sessCtx, t)
 	if err != nil {
 		return errors.Trace(err)
diff --git a/ddl/column.go b/ddl/column.go
index e9c353aacf2f5..37ad069900afc 100644
--- a/ddl/column.go
+++ b/ddl/column.go
@@ -1047,7 +1047,7 @@ func (w *worker) updatePhysicalTableRow(t table.Table, reorgInfo *reorgInfo) err
 			if p == nil {
 				return dbterror.ErrCancelledDDLJob.GenWithStack("Can not find partition id %d for table %d", reorgInfo.PhysicalTableID, t.Meta().ID)
 			}
-			err := w.writePhysicalTableRecord(w.sessPool, p, typeUpdateColumnWorker, reorgInfo)
+			err := w.writePhysicalTableRecord(w.sess, w.sessPool, p, typeUpdateColumnWorker, reorgInfo)
 			if err != nil {
 				return err
 			}
@@ -1059,7 +1059,7 @@ func (w *worker) updatePhysicalTableRow(t table.Table, reorgInfo *reorgInfo) err
 		return nil
 	}
 	if tbl, ok := t.(table.PhysicalTable); ok {
-		return w.writePhysicalTableRecord(w.sessPool, tbl, typeUpdateColumnWorker, reorgInfo)
+		return w.writePhysicalTableRecord(w.sess, w.sessPool, tbl, typeUpdateColumnWorker, reorgInfo)
 	}
 	return dbterror.ErrCancelledDDLJob.GenWithStack("internal error for phys tbl id: %d tbl id: %d", reorgInfo.PhysicalTableID, t.Meta().ID)
 }
diff --git a/ddl/index.go b/ddl/index.go
index 8ecc916e7b3f9..c252e213dc1da 100644
--- a/ddl/index.go
+++ b/ddl/index.go
@@ -1592,10 +1592,10 @@ func (w *addIndexWorker) BackfillDataInTxn(handleRange reorgBackfillTask) (taskC
 func (w *worker) addPhysicalTableIndex(t table.PhysicalTable, reorgInfo *reorgInfo) error {
 	if reorgInfo.mergingTmpIdx {
 		logutil.BgLogger().Info("[ddl] start to merge temp index", zap.String("job", reorgInfo.Job.String()), zap.String("reorgInfo", reorgInfo.String()))
-		return w.writePhysicalTableRecord(w.sessPool, t, typeAddIndexMergeTmpWorker, reorgInfo)
+		return w.writePhysicalTableRecord(w.sess, w.sessPool, t, typeAddIndexMergeTmpWorker, reorgInfo)
 	}
 	logutil.BgLogger().Info("[ddl] start to add table index", zap.String("job", reorgInfo.Job.String()), zap.String("reorgInfo", reorgInfo.String()))
-	return w.writePhysicalTableRecord(w.sessPool, t, typeAddIndexWorker, reorgInfo)
+	return w.writePhysicalTableRecord(w.sess, w.sessPool, t, typeAddIndexWorker, reorgInfo)
 }
 
 // addTableIndex handles the add index reorganization state for a table.
@@ -1804,7 +1804,7 @@ func (w *cleanUpIndexWorker) BackfillDataInTxn(handleRange reorgBackfillTask) (t
 // cleanupPhysicalTableIndex handles the drop partition reorganization state for a non-partitioned table or a partition.
 func (w *worker) cleanupPhysicalTableIndex(t table.PhysicalTable, reorgInfo *reorgInfo) error {
 	logutil.BgLogger().Info("[ddl] start to clean up index", zap.String("job", reorgInfo.Job.String()), zap.String("reorgInfo", reorgInfo.String()))
-	return w.writePhysicalTableRecord(w.sessPool, t, typeCleanUpIndexWorker, reorgInfo)
+	return w.writePhysicalTableRecord(w.sess, w.sessPool, t, typeCleanUpIndexWorker, reorgInfo)
 }
 
 // cleanupGlobalIndex handles the drop partition reorganization state to clean up index entries of partitions.