planner: fix TiDB server panic when uses indexMerge with the virtual …

…generated column (#17065)

expression/integration_test.go

@@ -6378,3 +6378,13 @@ func (s *testIntegrationSuite) TestIssue16779(c *C) {
 	tk.MustExec("create table t1 (c0 int)")
 	tk.MustQuery("SELECT * FROM t1 LEFT JOIN t0 ON TRUE WHERE BINARY EXPORT_SET(0, 0, 0 COLLATE 'binary', t0.c0, 0 COLLATE 'binary')")
 }
+
+func (s *testIntegrationSuite) TestIssue17045(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t(a int,b varchar(20),c datetime,d double,e int,f int as(a+b),key(a),key(b),key(c),key(d),key(e),key(f));")
+	tk.MustExec("insert into t(a,b,e) values(null,\"5\",null);")
+	tk.MustExec("insert into t(a,b,e) values(\"5\",null,null);")
+	tk.MustQuery("select /*+ use_index_merge(t)*/ * from t where t.e=5 or t.a=5;").Check(testkit.Rows("5 <nil> <nil> <nil> <nil> <nil>"))
+}

planner/core/find_best_task.go

@@ -671,6 +671,7 @@ func (ds *DataSource) buildIndexMergeTableScan(prop *property.PhysicalProperty,
 		physicalTableID: ds.physicalTableID,
 	}.Init(ds.ctx, ds.blockOffset)
 	ts.SetSchema(ds.schema.Clone())
+	ts.Columns = ExpandVirtualColumn(ts.Columns, ts.schema, ts.Table.Columns)
 	if ts.Table.PKIsHandle {
 		if pkColInfo := ts.Table.GetPkColInfo(); pkColInfo != nil {
 			if ds.statisticTable.Columns[pkColInfo.ID] != nil {

planner/core/resolve_indices.go

@@ -300,6 +300,10 @@ func (p *PhysicalIndexLookUpReader) ResolveIndices() (err error) {
 
 // ResolveIndices implements Plan interface.
 func (p *PhysicalIndexMergeReader) ResolveIndices() (err error) {
+	err = resolveIndicesForVirtualColumn(p.tablePlan.Schema().Columns, p.schema)
+	if err != nil {
+		return err
+	}
 	if p.tablePlan != nil {
 		err = p.tablePlan.ResolveIndices()
 		if err != nil {