planner: isolation read do not filter system tables (#17556) (#17719)

Signed-off-by: sre-bot <sre-bot@pingcap.com> Co-authored-by: Zhuomin(Charming) Liu <lzmhhh123@gmail.com>
pingcap · Jun 6, 2020 · 203ec5a · 203ec5a
1 parent a0ad6f6
commit 203ec5a
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Showing 4 changed files with 54 additions and 1 deletion.
diff --git a/planner/core/integration_test.go b/planner/core/integration_test.go
@@ -532,6 +532,27 @@ func (s *testIntegrationSerialSuite) TestIsolationReadTiFlashUseIndexHint(c *C)
 	}
 }
 
+func (s *testIntegrationSerialSuite) TestIsolationReadDoNotFilterSystemDB(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+
+	tk.MustExec("use test")
+	tk.MustExec("set @@tidb_isolation_read_engines = \"tiflash\"")
+	var input []string
+	var output []struct {
+		SQL  string
+		Plan []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())
+		})
+		res := tk.MustQuery(tt)
+		res.Check(testkit.Rows(output[i].Plan...))
+	}
+}
+
 func (s *testIntegrationSuite) TestPartitionTableStats(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 

diff --git a/planner/core/planbuilder.go b/planner/core/planbuilder.go
@@ -828,7 +828,7 @@ func (b *PlanBuilder) filterPathByIsolationRead(paths []*util.AccessPath, dbName
 			}
 			availableEngineStr += paths[i].StoreType.Name()
 		}
-		if _, ok := isolationReadEngines[paths[i].StoreType]; !ok {
+		if _, ok := isolationReadEngines[paths[i].StoreType]; !ok && paths[i].StoreType != kv.TiDB {
 			paths = append(paths[:i], paths[i+1:]...)
 		}
 	}

diff --git a/planner/core/testdata/integration_serial_suite_in.json b/planner/core/testdata/integration_serial_suite_in.json
@@ -42,6 +42,14 @@
       "desc select /*+ read_from_storage(tiflash[t]) */ avg(a) from t"
     ]
   },
+  {
+    "name": "TestIsolationReadDoNotFilterSystemDB",
+    "cases": [
+      "desc select * from metrics_schema.tidb_query_duration where time >= '2019-12-23 16:10:13' and time <= '2019-12-23 16:30:13'",
+      "desc select * from information_schema.tables",
+      "desc select * from mysql.stats_meta"
+    ]
+  },
   {
     "name": "TestIsolationReadTiFlashNotChoosePointGet",
     "cases": [

diff --git a/planner/core/testdata/integration_serial_suite_out.json b/planner/core/testdata/integration_serial_suite_out.json
@@ -240,6 +240,30 @@
       }
     ]
   },
+  {
+    "Name": "TestIsolationReadDoNotFilterSystemDB",
+    "Cases": [
+      {
+        "SQL": "desc select * from metrics_schema.tidb_query_duration where time >= '2019-12-23 16:10:13' and time <= '2019-12-23 16:30:13'",
+        "Plan": [
+          "MemTableScan_5 10000.00 root table:tidb_query_duration PromQL:histogram_quantile(0.9, sum(rate(tidb_server_handle_query_duration_seconds_bucket{}[60s])) by (le,sql_type,instance)), start_time:2019-12-23 16:10:13, end_time:2019-12-23 16:30:13, step:1m0s"
+        ]
+      },
+      {
+        "SQL": "desc select * from information_schema.tables",
+        "Plan": [
+          "MemTableScan_4 10000.00 root table:TABLES "
+        ]
+      },
+      {
+        "SQL": "desc select * from mysql.stats_meta",
+        "Plan": [
+          "TableReader_5 10000.00 root  data:TableFullScan_4",
+          "└─TableFullScan_4 10000.00 cop[tikv] table:stats_meta keep order:false, stats:pseudo"
+        ]
+      }
+    ]
+  },
   {
     "Name": "TestIsolationReadTiFlashNotChoosePointGet",
     "Cases": [