planner: check readEngines when building plan for index hint (#15723)

planner/core/integration_test.go

@@ -416,6 +416,45 @@ func (s *testIntegrationSuite) TestReadFromStorageHintAndIsolationRead(c *C) {
 	}
 }
 
+func (s *testIntegrationSuite) TestIsolationReadTiFlashUseIndexHint(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, index idx(a));")
+
+	// Create virtual tiflash replica info.
+	dom := domain.GetDomain(tk.Se)
+	is := dom.InfoSchema()
+	db, exists := is.SchemaByName(model.NewCIStr("test"))
+	c.Assert(exists, IsTrue)
+	for _, tblInfo := range db.Tables {
+		tblInfo.TiFlashReplica = &model.TiFlashReplicaInfo{
+			Count:     1,
+			Available: true,
+		}
+	}
+
+	tk.MustExec("set @@session.tidb_isolation_read_engines=\"tiflash\"")
+	var input []string
+	var output []struct {
+		SQL  string
+		Plan []string
+		Warn []string
+	}
+	s.testData.GetTestCases(c, &input, &output)
+	for i, tt := range input {
+		s.testData.OnRecord(func() {
+			output[i].SQL = tt
+			output[i].Plan = s.testData.ConvertRowsToStrings(tk.MustQuery(tt).Rows())
+			output[i].Warn = s.testData.ConvertSQLWarnToStrings(tk.Se.GetSessionVars().StmtCtx.GetWarnings())
+		})
+		res := tk.MustQuery(tt)
+		res.Check(testkit.Rows(output[i].Plan...))
+		c.Assert(s.testData.ConvertSQLWarnToStrings(tk.Se.GetSessionVars().StmtCtx.GetWarnings()), DeepEquals, output[i].Warn)
+	}
+}
+
 func (s *testIntegrationSuite) TestPartitionTableStats(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 

planner/core/planbuilder.go

@@ -564,13 +564,25 @@ func (b *PlanBuilder) getPossibleAccessPaths(indexHints []*ast.IndexHint, tblInf
 		}
 	}
 
+	_, isolationReadEnginesHasTiKV := b.ctx.GetSessionVars().GetIsolationReadEngines()[kv.TiKV]
 	for i, hint := range indexHints {
 		if hint.HintScope != ast.HintForScan {
 			continue
 		}
 
 		hasScanHint = true
 
+		if !isolationReadEnginesHasTiKV {
+			if hint.IndexNames != nil {
+				engineVals, _ := b.ctx.GetSessionVars().GetSystemVar(variable.TiDBIsolationReadEngines)
+				err := errors.New(fmt.Sprintf("TiDB doesn't support index in the isolation read engines(value: '%v')", engineVals))
+				if i < indexHintsLen {
+					return nil, err
+				}
+				b.ctx.GetSessionVars().StmtCtx.AppendWarning(err)
+			}
+			continue
+		}
 		// It is syntactically valid to omit index_list for USE INDEX, which means “use no indexes”.
 		// Omitting index_list for FORCE INDEX or IGNORE INDEX is a syntax error.
 		// See https://dev.mysql.com/doc/refman/8.0/en/index-hints.html.

planner/core/testdata/integration_suite_in.json

@@ -63,5 +63,14 @@
       "desc select /*+ read_from_storage(tikv[t]) */ avg(a) from t",
       "desc select /*+ read_from_storage(tiflash[t]) */ avg(a) from t"
     ]
+  },
+  {
+    "name": "TestIsolationReadTiFlashUseIndexHint",
+    "cases": [
+      "explain select * from t",
+      "explain select * from t use index();",
+      "explain select /*+ use_index(t, idx)*/ * from t",
+      "explain select /*+ use_index(t)*/ * from t"
+    ]
   }
 ]

planner/core/testdata/integration_suite_out.json

@@ -247,5 +247,44 @@
         ]
       }
     ]
+  },
+  {
+    "Name": "TestIsolationReadTiFlashUseIndexHint",
+    "Cases": [
+      {
+        "SQL": "explain select * from t",
+        "Plan": [
+          "TableReader_5 10000.00 root data:TableScan_4",
+          "└─TableScan_4 10000.00 cop[tiflash] table:t, range:[-inf,+inf], keep order:false, stats:pseudo"
+        ],
+        "Warn": null
+      },
+      {
+        "SQL": "explain select * from t use index();",
+        "Plan": [
+          "TableReader_5 10000.00 root data:TableScan_4",
+          "└─TableScan_4 10000.00 cop[tiflash] table:t, range:[-inf,+inf], keep order:false, stats:pseudo"
+        ],
+        "Warn": null
+      },
+      {
+        "SQL": "explain select /*+ use_index(t, idx)*/ * from t",
+        "Plan": [
+          "TableReader_5 10000.00 root data:TableScan_4",
+          "└─TableScan_4 10000.00 cop[tiflash] table:t, range:[-inf,+inf], keep order:false, stats:pseudo"
+        ],
+        "Warn": [
+          "TiDB doesn't support index in the isolation read engines(value: 'tiflash')"
+        ]
+      },
+      {
+        "SQL": "explain select /*+ use_index(t)*/ * from t",
+        "Plan": [
+          "TableReader_5 10000.00 root data:TableScan_4",
+          "└─TableScan_4 10000.00 cop[tiflash] table:t, range:[-inf,+inf], keep order:false, stats:pseudo"
+        ],
+        "Warn": null
+      }
+    ]
   }
 ]