planner: handle the expected row count for pushed-down selection in m…

…pp (#36195) close #36194
pingcap · Jul 13, 2022 · 24eb419 · 24eb419
1 parent 2f934d6
commit 24eb419
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Showing 3 changed files with 32 additions and 4 deletions.
diff --git a/planner/core/find_best_task.go b/planner/core/find_best_task.go
@@ -1917,7 +1917,7 @@ func (ds *DataSource) convertToTableScan(prop *property.PhysicalProperty, candid
 			ColumnNames:    ds.names,
 		}
 		ts.cost = cost
-		mppTask = ts.addPushedDownSelectionToMppTask(mppTask, ds.stats)
+		mppTask = ts.addPushedDownSelectionToMppTask(mppTask, ds.stats.ScaleByExpectCnt(prop.ExpectedCnt))
 		return mppTask, nil
 	}
 	copTask := &copTask{

diff --git a/planner/core/integration_test.go b/planner/core/integration_test.go
@@ -6989,3 +6989,31 @@ func TestIssue25813(t *testing.T) {
 		"  └─TableReader(Probe) 10000.00 root  data:TableFullScan",
 		"    └─TableFullScan 10000.00 cop[tikv] table:t1 keep order:false, stats:pseudo"))
 }
+
+func TestIssue36194(t *testing.T) {
+	store, dom, clean := testkit.CreateMockStoreAndDomain(t)
+	defer clean()
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t(a int)")
+	// create virtual tiflash replica.
+	is := dom.InfoSchema()
+	db, exists := is.SchemaByName(model.NewCIStr("test"))
+	require.True(t, exists)
+	for _, tblInfo := range db.Tables {
+		if tblInfo.Name.L == "t" {
+			tblInfo.TiFlashReplica = &model.TiFlashReplicaInfo{
+				Count:     1,
+				Available: true,
+			}
+		}
+	}
+	tk.MustQuery("explain format = 'brief' select * from t where a + 1 > 20 limit 100;;").Check(testkit.Rows(
+		"Limit 100.00 root  offset:0, count:100",
+		"└─TableReader 100.00 root  data:ExchangeSender",
+		"  └─ExchangeSender 100.00 mpp[tiflash]  ExchangeType: PassThrough",
+		"    └─Limit 100.00 mpp[tiflash]  offset:0, count:100",
+		"      └─Selection 100.00 mpp[tiflash]  gt(plus(test.t.a, 1), 20)",
+		"        └─TableFullScan 125.00 mpp[tiflash] table:t keep order:false, stats:pseudo"))
+}
diff --git a/planner/core/testdata/integration_suite_out.json b/planner/core/testdata/integration_suite_out.json
@@ -5952,7 +5952,7 @@
           "        │ └─ExchangeSender 9990.00 mpp[tiflash]  ExchangeType: Broadcast",
           "        │   └─Selection 9990.00 mpp[tiflash]  not(isnull(test.t.id))",
           "        │     └─TableFullScan 10000.00 mpp[tiflash] table:t keep order:false, stats:pseudo",
-          "        └─Selection(Probe) 9990.00 mpp[tiflash]  not(isnull(test.t.id))",
+          "        └─Selection(Probe) 0.80 mpp[tiflash]  not(isnull(test.t.id))",
           "          └─TableFullScan 0.80 mpp[tiflash] table:t1 keep order:false, stats:pseudo"
         ]
       },
@@ -5968,7 +5968,7 @@
           "        │ └─ExchangeSender 9990.00 mpp[tiflash]  ExchangeType: Broadcast",
           "        │   └─Selection 9990.00 mpp[tiflash]  not(isnull(test.t.id))",
           "        │     └─TableFullScan 10000.00 mpp[tiflash] table:t keep order:false, stats:pseudo",
-          "        └─Selection(Probe) 9990.00 mpp[tiflash]  not(isnull(test.t.id))",
+          "        └─Selection(Probe) 0.80 mpp[tiflash]  not(isnull(test.t.id))",
           "          └─TableFullScan 0.80 mpp[tiflash] table:t1 keep order:false, stats:pseudo"
         ]
       },
@@ -5985,7 +5985,7 @@
           "          │ └─ExchangeSender 9990.00 mpp[tiflash]  ExchangeType: Broadcast",
           "          │   └─Selection 9990.00 mpp[tiflash]  not(isnull(test.t.id))",
           "          │     └─TableFullScan 10000.00 mpp[tiflash] table:t keep order:false, stats:pseudo",
-          "          └─Selection(Probe) 9990.00 mpp[tiflash]  not(isnull(test.t.id))",
+          "          └─Selection(Probe) 16.00 mpp[tiflash]  not(isnull(test.t.id))",
           "            └─TableFullScan 16.02 mpp[tiflash] table:t1 keep order:false, stats:pseudo"
         ]
       }