planner: add Fix52592 control to disallow fast path (#56097)

close #52592

pkg/planner/core/find_best_task.go

@@ -1420,6 +1420,9 @@ func findBestTask4DS(ds *DataSource, prop *property.PhysicalProperty, planCounte
 		}
 
 		canConvertPointGet := len(path.Ranges) > 0 && path.StoreType == kv.TiKV && isPointGetConvertableSchema(ds)
+		if fixcontrol.GetBoolWithDefault(ds.SCtx().GetSessionVars().OptimizerFixControl, fixcontrol.Fix52592, false) {
+			canConvertPointGet = false
+		}
 
 		if canConvertPointGet && path.Index != nil && path.Index.MVIndex {
 			canConvertPointGet = false // cannot use PointGet upon MVIndex

pkg/planner/core/point_get_plan.go

@@ -41,6 +41,7 @@ import (
 	"github.com/pingcap/tidb/pkg/planner/property"
 	"github.com/pingcap/tidb/pkg/planner/util"
 	"github.com/pingcap/tidb/pkg/planner/util/costusage"
+	"github.com/pingcap/tidb/pkg/planner/util/fixcontrol"
 	"github.com/pingcap/tidb/pkg/planner/util/optimizetrace"
 	"github.com/pingcap/tidb/pkg/privilege"
 	"github.com/pingcap/tidb/pkg/sessionctx"
@@ -883,8 +884,9 @@ type PointPlanVal struct {
 
 // TryFastPlan tries to use the PointGetPlan for the query.
 func TryFastPlan(ctx base.PlanContext, node *resolve.NodeW) (p base.Plan) {
-	if checkStableResultMode(ctx) {
+	if checkStableResultMode(ctx) || fixcontrol.GetBoolWithDefault(ctx.GetSessionVars().OptimizerFixControl, fixcontrol.Fix52592, false) {
 		// the rule of stabilizing results has not taken effect yet, so cannot generate a plan here in this mode
+		// or Fix52592 is turn on to disable fast path for select, update and delete
 		return nil
 	}
 

pkg/planner/core/point_get_plan_test.go

@@ -226,3 +226,52 @@ func TestIssue18042(t *testing.T) {
 	require.Equal(t, uint64(100), tk.Session().GetSessionVars().StmtCtx.MaxExecutionTime)
 	tk.MustExec("drop table t")
 }
+
+func TestIssue52592(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec(`set @@tidb_opt_fix_control = "52592:OFF"`) // affect hit counter in this ut
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t(a bigint unsigned primary key, b int, c int, key idx_bc(b,c))")
+	tk.MustExec("insert into t values(1, 1, 1), (2, 2, 2), (3, 3, 3)")
+	tk.MustQuery("explain format = 'brief' select * from t where a = 1").Check(testkit.Rows(
+		"Point_Get 1.00 root table:t handle:1",
+	))
+	tk.MustQuery("explain format = 'brief' select * from t where 1 = a").Check(testkit.Rows(
+		"Point_Get 1.00 root table:t handle:1",
+	))
+	tk.MustQuery("explain format = 'brief' update t set b=b+1, c=c+1 where a = 1").Check(testkit.Rows(
+		"Update N/A root  N/A",
+		"└─Point_Get 1.00 root table:t handle:1",
+	))
+	tk.MustQuery("explain format = 'brief' delete from t where a = 1").Check(testkit.Rows(
+		"Delete N/A root  N/A",
+		"└─Point_Get 1.00 root table:t handle:1",
+	))
+	tk.MustQuery("explain format = 'brief' select a from t where a = -1").Check(testkit.Rows(
+		"TableDual 0.00 root  rows:0",
+	))
+	tk.MustExec(`set @@tidb_opt_fix_control = "52592:ON"`)
+	tk.MustQuery("explain format = 'brief' select * from t where a = 1").Check(testkit.Rows(
+		"TableReader 1.00 root  data:TableRangeScan",
+		"└─TableRangeScan 1.00 cop[tikv] table:t range:[1,1], keep order:false, stats:pseudo",
+	))
+	tk.MustQuery("explain format = 'brief' select * from t where 1 = a").Check(testkit.Rows(
+		"TableReader 1.00 root  data:TableRangeScan",
+		"└─TableRangeScan 1.00 cop[tikv] table:t range:[1,1], keep order:false, stats:pseudo",
+	))
+	tk.MustQuery("explain format = 'brief' update t set b=b+1, c=c+1 where a = 1").Check(testkit.Rows(
+		"Update N/A root  N/A",
+		"└─TableReader 1.00 root  data:TableRangeScan",
+		"  └─TableRangeScan 1.00 cop[tikv] table:t range:[1,1], keep order:false, stats:pseudo",
+	))
+	tk.MustQuery("explain format = 'brief' delete from t where a = 1").Check(testkit.Rows(
+		"Delete N/A root  N/A",
+		"└─TableReader 1.00 root  data:TableRangeScan",
+		"  └─TableRangeScan 1.00 cop[tikv] table:t range:[1,1], keep order:false, stats:pseudo",
+	))
+	tk.MustQuery("explain format = 'brief' select a from t where a = -1").Check(testkit.Rows(
+		"TableDual 0.00 root  rows:0",
+	))
+}

pkg/planner/util/fixcontrol/get.go

@@ -23,6 +23,16 @@ import (
 )
 
 const (
+	// Fix52592 controls whether to disallow fast path for Get and BatchGet.
+	// Fast path does not support column projection, so we need to disable it when column projection is required.
+	// Here are the common cases that column projection is required:
+	// 1. Wide tables with many columns, where applications only query a few columns.
+	// 2. JSON fields with large column values, where queries may not necessarily retrieve the values of JSON columns
+	//    or only extract specific small JSON content.
+	// By default, fast path is enabled, when it's disabled, the optimizer will fallback to coproccessor.
+	// It should be only disabled when fast path is more expensive than coprocessor.
+	// See #52592
+	Fix52592 uint64 = 52592
 	// Fix33031 controls whether to disallow plan cache for partitioned
 	// tables (both prepared statments and non-prepared statements)
 	// See #33031