planner: fix index join on unmatched collation suffix columns paniced

expression/integration_test.go

@@ -8494,6 +8494,18 @@ func (s *testIntegrationSerialSuite) TestCollationIndexJoin(c *C) {
 	tk.MustQuery("select /*+ inl_merge_join(t1) */ t1.b, t2.b from t1 join t2 where t1.b=t2.b").Check(testkit.Rows("a A"))
 	tk.MustQuery("select /*+ inl_merge_join(t2) */ t1.b, t2.b from t1 join t2 where t1.b=t2.b").Check(testkit.Rows("a A"))
 	tk.MustQuery("show warnings").Check(testkit.Rows("Warning 1815 Optimizer Hint /*+ INL_MERGE_JOIN(t2) */ is inapplicable"))
+
+	tk.MustExec("drop table if exists a, b")
+	tk.MustExec("create table a(i int, k varbinary(40), v int, primary key(i, k) clustered)")
+	tk.MustExec("create table b(i int, k varchar(40), v int, primary key(i, k) clustered)")
+	tk.MustExec("insert into a select 3, 'nice mccarthy', 10")
+	tk.MustQuery("select * from a, b where a.i = b.i and a.k = b.k").Check(testkit.Rows())
+
+	tk.MustExec("drop table if exists a, b")
+	tk.MustExec("create table a(i int  NOT NULL, k varbinary(40)  NOT NULL, v int, key idx1(i, k))")
+	tk.MustExec("create table b(i int  NOT NULL, k varchar(40)  NOT NULL, v int, key idx1(i, k))")
+	tk.MustExec("insert into a select 3, 'nice mccarthy', 10")
+	tk.MustQuery(" select /*+ inl_join(b) */ b.i from a, b where a.i = b.i and a.k = b.k").Check(testkit.Rows())
 }
 
 func (s *testIntegrationSerialSuite) TestCollationMergeJoin(c *C) {

planner/core/exhaust_physical_plans.go

@@ -1212,14 +1212,21 @@ func (cwc *ColWithCmpFuncManager) String() string {
 	return buffer.String()
 }
 
-func (ijHelper *indexJoinBuildHelper) resetContextForIndex(innerKeys []*expression.Column, idxCols []*expression.Column, colLens []int) {
+func (ijHelper *indexJoinBuildHelper) resetContextForIndex(innerKeys []*expression.Column, idxCols []*expression.Column, colLens []int, outerKeys []*expression.Column) {
 	tmpSchema := expression.NewSchema(innerKeys...)
 	ijHelper.curIdxOff2KeyOff = make([]int, len(idxCols))
 	ijHelper.curNotUsedIndexCols = make([]*expression.Column, 0, len(idxCols))
 	ijHelper.curNotUsedColLens = make([]int, 0, len(idxCols))
 	for i, idxCol := range idxCols {
 		ijHelper.curIdxOff2KeyOff[i] = tmpSchema.ColumnIndex(idxCol)
 		if ijHelper.curIdxOff2KeyOff[i] >= 0 {
+			// Don't use the join columns if their collations are unmatched and the new collation is enabled.
+			if collate.NewCollationEnabled() && types.IsString(idxCol.RetType.Tp) && types.IsString(outerKeys[ijHelper.curIdxOff2KeyOff[i]].RetType.Tp) {
+				_, coll := expression.DeriveCollationFromExprs(nil, idxCol, outerKeys[ijHelper.curIdxOff2KeyOff[i]])
+				if !collate.CompatibleCollate(idxCol.GetType().Collate, coll) {
+					ijHelper.curIdxOff2KeyOff[i] = -1
+				}
+			}
 			continue
 		}
 		ijHelper.curNotUsedIndexCols = append(ijHelper.curNotUsedIndexCols, idxCol)
@@ -1294,12 +1301,8 @@ func (ijHelper *indexJoinBuildHelper) removeUselessEqAndInFunc(idxCols []*expres
 	ijHelper.curPossibleUsedKeys = make([]*expression.Column, 0, len(idxCols))
 	for idxColPos, notKeyColPos := 0, 0; idxColPos < len(idxCols); idxColPos++ {
 		if ijHelper.curIdxOff2KeyOff[idxColPos] != -1 {
-			// Check collation is the new collation is enabled.
-			_, coll := expression.DeriveCollationFromExprs(nil, idxCols[idxColPos], outerJoinKeys[ijHelper.curIdxOff2KeyOff[idxColPos]])
-			if !collate.NewCollationEnabled() || collate.CompatibleCollate(idxCols[idxColPos].GetType().Collate, coll) {
-				ijHelper.curPossibleUsedKeys = append(ijHelper.curPossibleUsedKeys, idxCols[idxColPos])
-				continue
-			}
+			ijHelper.curPossibleUsedKeys = append(ijHelper.curPossibleUsedKeys, idxCols[idxColPos])
+			continue
 		}
 		if notKeyColPos < len(notKeyEqAndIn) && ijHelper.curNotUsedIndexCols[notKeyColPos].Equal(nil, idxCols[idxColPos]) {
 			notKeyColPos++
@@ -1321,7 +1324,7 @@ func (ijHelper *indexJoinBuildHelper) analyzeLookUpFilters(path *util.AccessPath
 		return false, nil
 	}
 	accesses := make([]expression.Expression, 0, len(path.IdxCols))
-	ijHelper.resetContextForIndex(innerJoinKeys, path.IdxCols, path.IdxColLens)
+	ijHelper.resetContextForIndex(innerJoinKeys, path.IdxCols, path.IdxColLens, outerJoinKeys)
 	notKeyEqAndIn, remained, rangeFilterCandidates := ijHelper.findUsefulEqAndInFilters(innerPlan)
 	var remainedEqAndIn []expression.Expression
 	notKeyEqAndIn, remainedEqAndIn = ijHelper.removeUselessEqAndInFunc(path.IdxCols, notKeyEqAndIn, outerJoinKeys)