From 702c864300489aac9bd300bb506deb9b77c0f1c4 Mon Sep 17 00:00:00 2001
From: Ti Chi Robot <ti-community-prow-bot@tidb.io>
Date: Thu, 6 Jun 2024 17:20:56 +0800
Subject: [PATCH] *: check delete unique key's handle to handle corner case
 (#52975) (#53701)

close pingcap/tidb#52914
---
 table/tables/index.go | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/table/tables/index.go b/table/tables/index.go
index b8a164a9b2ece..ca51c03e2215b 100644
--- a/table/tables/index.go
+++ b/table/tables/index.go
@@ -340,9 +340,28 @@ func (c *index) Delete(sc *stmtctx.StatementContext, txn kv.Transaction, indexed
 
 	if distinct {
 		if len(key) > 0 {
-			err = txn.GetMemBuffer().DeleteWithFlags(key, kv.SetNeedLocked)
-			if err != nil {
-				return err
+			okToDelete := true
+			if c.idxInfo.BackfillState != model.BackfillStateInapplicable {
+				// #52914: the delete key is covered by the new ingested key, which shouldn't be deleted.
+				originVal, err := getKeyInTxn(context.TODO(), txn, key)
+				if err != nil {
+					return err
+				}
+				if len(originVal) > 0 {
+					oh, err := tablecodec.DecodeHandleInUniqueIndexValue(originVal, c.tblInfo.IsCommonHandle)
+					if err != nil {
+						return err
+					}
+					if !h.Equal(oh) {
+						okToDelete = false
+					}
+				}
+			}
+			if okToDelete {
+				err = txn.GetMemBuffer().DeleteWithFlags(key, kv.SetNeedLocked)
+				if err != nil {
+					return err
+				}
 			}
 		}
 		if len(tempKey) > 0 {