planner, executor: support point get as a option of DataSource

cmd/explaintest/r/explain_easy.result

@@ -86,9 +86,8 @@ IndexLookUp_11	11.08	root
   └─TableRowIDScan_9	33.33	cop[tikv]	table:t1, keep order:false, stats:pseudo
 explain select * from t1 where c1 = 1 and c2 > 1;
 id	estRows	task	operator info
-TableReader_7	0.33	root	data:Selection_6
-└─Selection_6	0.33	cop[tikv]	gt(test.t1.c2, 1)
-  └─TableRangeScan_5	1.00	cop[tikv]	table:t1, range:[1,1], keep order:false, stats:pseudo
+Selection_6	0.33	root	gt(test.t1.c2, 1)
+└─Point_Get_5	1.00	root	table:t1, handle:1
 explain select sum(t1.c1 in (select c1 from t2)) from t1;
 id	estRows	task	operator info
 StreamAgg_12	1.00	root	funcs:sum(Column#10)->Column#8

cmd/explaintest/r/explain_easy_stats.result

@@ -86,9 +86,8 @@ IndexLookUp_11	0.00	root
   └─TableRowIDScan_9	0.00	cop[tikv]	table:t1, keep order:false
 explain select * from t1 where c1 = 1 and c2 > 1;
 id	estRows	task	operator info
-TableReader_7	0.50	root	data:Selection_6
-└─Selection_6	0.50	cop[tikv]	gt(test.t1.c2, 1)
-  └─TableRangeScan_5	1.00	cop[tikv]	table:t1, range:[1,1], keep order:false
+Selection_6	0.50	root	gt(test.t1.c2, 1)
+└─Point_Get_5	1.00	root	table:t1, handle:1
 explain select c1 from t1 where c1 in (select c2 from t2);
 id	estRows	task	operator info
 HashLeftJoin_19	1985.00	root	inner join, inner:HashAgg_23, equal:[eq(test.t1.c1, test.t2.c2)]
@@ -162,16 +161,12 @@ id	estRows	task	operator info
 TableDual_5	0.00	root	rows:0
 explain select * from index_prune WHERE a = 1010010404050976781 AND b = 26467085526790 LIMIT 1, 1;
 id	estRows	task	operator info
-IndexLookUp_14	1.00	root	limit embedded(offset:1, count:1)
-├─Limit_13(Build)	1.00	cop[tikv]	offset:0, count:2
-│ └─IndexRangeScan_11	1.00	cop[tikv]	table:index_prune, index:a, b, range:[1010010404050976781 26467085526790,1010010404050976781 26467085526790], keep order:false
-└─TableRowIDScan_12(Probe)	1.00	cop[tikv]	table:index_prune, keep order:false, stats:pseudo
+Limit_9	1.00	root	offset:1, count:1
+└─Point_Get_11	1.00	root	table:index_prune, index:a b
 explain select * from index_prune WHERE a = 1010010404050976781 AND b = 26467085526790 LIMIT 1, 0;
 id	estRows	task	operator info
-IndexLookUp_14	0.00	root	limit embedded(offset:1, count:0)
-├─Limit_13(Build)	1.00	cop[tikv]	offset:0, count:1
-│ └─IndexRangeScan_11	1.00	cop[tikv]	table:index_prune, index:a, b, range:[1010010404050976781 26467085526790,1010010404050976781 26467085526790], keep order:false
-└─TableRowIDScan_12(Probe)	0.00	cop[tikv]	table:index_prune, keep order:false, stats:pseudo
+Limit_9	0.00	root	offset:1, count:0
+└─Point_Get_11	1.00	root	table:index_prune, index:a b
 explain select * from index_prune WHERE a = 1010010404050976781 AND b = 26467085526790 LIMIT 0, 1;
 id	estRows	task	operator info
 Point_Get_1	1.00	root	table:index_prune, index:a b

cmd/explaintest/r/partition_pruning.result

@@ -334,50 +334,43 @@ a
 1
 EXPLAIN SELECT * FROM t1 WHERE a = 1;
 id	estRows	task	operator info
-TableReader_7	1.00	root	data:TableRangeScan_6
-└─TableRangeScan_6	1.00	cop[tikv]	table:t1, partition:p1, range:[1,1], keep order:false, stats:pseudo
+Point_Get_6	1.00	root	table:t1, handle:1, partition:p1
 SELECT * FROM t1 WHERE a = 2 order by a;
 a
 2
 EXPLAIN SELECT * FROM t1 WHERE a = 2;
 id	estRows	task	operator info
-TableReader_7	1.00	root	data:TableRangeScan_6
-└─TableRangeScan_6	1.00	cop[tikv]	table:t1, partition:p2, range:[2,2], keep order:false, stats:pseudo
+Point_Get_6	1.00	root	table:t1, handle:2, partition:p2
 SELECT * FROM t1 WHERE a = 3 order by a;
 a
 3
 EXPLAIN SELECT * FROM t1 WHERE a = 3;
 id	estRows	task	operator info
-TableReader_7	1.00	root	data:TableRangeScan_6
-└─TableRangeScan_6	1.00	cop[tikv]	table:t1, partition:p3, range:[3,3], keep order:false, stats:pseudo
+Point_Get_6	1.00	root	table:t1, handle:3, partition:p3
 SELECT * FROM t1 WHERE a = 4 order by a;
 a
 4
 EXPLAIN SELECT * FROM t1 WHERE a = 4;
 id	estRows	task	operator info
-TableReader_7	1.00	root	data:TableRangeScan_6
-└─TableRangeScan_6	1.00	cop[tikv]	table:t1, partition:p4, range:[4,4], keep order:false, stats:pseudo
+Point_Get_6	1.00	root	table:t1, handle:4, partition:p4
 SELECT * FROM t1 WHERE a = 5 order by a;
 a
 5
 EXPLAIN SELECT * FROM t1 WHERE a = 5;
 id	estRows	task	operator info
-TableReader_7	1.00	root	data:TableRangeScan_6
-└─TableRangeScan_6	1.00	cop[tikv]	table:t1, partition:p5, range:[5,5], keep order:false, stats:pseudo
+Point_Get_6	1.00	root	table:t1, handle:5, partition:p5
 SELECT * FROM t1 WHERE a = 6 order by a;
 a
 6
 EXPLAIN SELECT * FROM t1 WHERE a = 6;
 id	estRows	task	operator info
-TableReader_7	1.00	root	data:TableRangeScan_6
-└─TableRangeScan_6	1.00	cop[tikv]	table:t1, partition:max, range:[6,6], keep order:false, stats:pseudo
+Point_Get_6	1.00	root	table:t1, handle:6, partition:max
 SELECT * FROM t1 WHERE a = 7 order by a;
 a
 7
 EXPLAIN SELECT * FROM t1 WHERE a = 7;
 id	estRows	task	operator info
-TableReader_7	1.00	root	data:TableRangeScan_6
-└─TableRangeScan_6	1.00	cop[tikv]	table:t1, partition:max, range:[7,7], keep order:false, stats:pseudo
+Point_Get_6	1.00	root	table:t1, handle:7, partition:max
 SELECT * FROM t1 WHERE a >= 1 order by a;
 a
 1
@@ -812,43 +805,37 @@ a
 1
 EXPLAIN SELECT * FROM t1 WHERE a = 1;
 id	estRows	task	operator info
-TableReader_7	1.00	root	data:TableRangeScan_6
-└─TableRangeScan_6	1.00	cop[tikv]	table:t1, partition:p1, range:[1,1], keep order:false, stats:pseudo
+Point_Get_6	1.00	root	table:t1, handle:1, partition:p1
 SELECT * FROM t1 WHERE a = 2;
 a
 2
 EXPLAIN SELECT * FROM t1 WHERE a = 2;
 id	estRows	task	operator info
-TableReader_7	1.00	root	data:TableRangeScan_6
-└─TableRangeScan_6	1.00	cop[tikv]	table:t1, partition:p2, range:[2,2], keep order:false, stats:pseudo
+Point_Get_6	1.00	root	table:t1, handle:2, partition:p2
 SELECT * FROM t1 WHERE a = 3;
 a
 3
 EXPLAIN SELECT * FROM t1 WHERE a = 3;
 id	estRows	task	operator info
-TableReader_7	1.00	root	data:TableRangeScan_6
-└─TableRangeScan_6	1.00	cop[tikv]	table:t1, partition:p3, range:[3,3], keep order:false, stats:pseudo
+Point_Get_6	1.00	root	table:t1, handle:3, partition:p3
 SELECT * FROM t1 WHERE a = 4;
 a
 4
 EXPLAIN SELECT * FROM t1 WHERE a = 4;
 id	estRows	task	operator info
-TableReader_7	1.00	root	data:TableRangeScan_6
-└─TableRangeScan_6	1.00	cop[tikv]	table:t1, partition:p4, range:[4,4], keep order:false, stats:pseudo
+Point_Get_6	1.00	root	table:t1, handle:4, partition:p4
 SELECT * FROM t1 WHERE a = 5;
 a
 5
 EXPLAIN SELECT * FROM t1 WHERE a = 5;
 id	estRows	task	operator info
-TableReader_7	1.00	root	data:TableRangeScan_6
-└─TableRangeScan_6	1.00	cop[tikv]	table:t1, partition:max, range:[5,5], keep order:false, stats:pseudo
+Point_Get_6	1.00	root	table:t1, handle:5, partition:max
 SELECT * FROM t1 WHERE a = 6;
 a
 6
 EXPLAIN SELECT * FROM t1 WHERE a = 6;
 id	estRows	task	operator info
-TableReader_7	1.00	root	data:TableRangeScan_6
-└─TableRangeScan_6	1.00	cop[tikv]	table:t1, partition:max, range:[6,6], keep order:false, stats:pseudo
+Point_Get_6	1.00	root	table:t1, handle:6, partition:max
 SELECT * FROM t1 WHERE a >= 1 order by a;
 a
 1

executor/batch_point_get.go

@@ -15,6 +15,7 @@ package executor
 
 import (
 	"context"
+	"sort"
 
 	"github.com/pingcap/failpoint"
 	"github.com/pingcap/parser/model"
@@ -44,6 +45,8 @@ type BatchPointGetExec struct {
 	values     [][]byte
 	index      int
 	rowDecoder *rowcodec.ChunkDecoder
+	keepOrder  bool
+	desc       bool
 }
 
 // Open implements the Executor interface.
@@ -118,6 +121,14 @@ func (e *BatchPointGetExec) initialize(ctx context.Context) error {
 			dedup[s] = struct{}{}
 			keys = append(keys, idxKey)
 		}
+		if e.keepOrder {
+			sort.Slice(keys, func(i int, j int) bool {
+				if e.desc {
+					return keys[i].Cmp(keys[j]) > 0
+				}
+				return keys[i].Cmp(keys[j]) < 0
+			})
+		}
 
 		// Fetch all handles.
 		handleVals, err = batchGetter.BatchGet(ctx, keys)
@@ -151,6 +162,13 @@ func (e *BatchPointGetExec) initialize(ctx context.Context) error {
 			// Wait `UPDATE` finished
 			failpoint.InjectContext(ctx, "batchPointGetRepeatableReadTest-step2", nil)
 		})
+	} else if e.keepOrder {
+		sort.Slice(e.handles, func(i int, j int) bool {
+			if e.desc {
+				return e.handles[i] > e.handles[j]
+			}
+			return e.handles[i] < e.handles[j]
+		})
 	}
 
 	keys := make([]kv.Key, len(e.handles))

executor/builder.go

@@ -2403,6 +2403,7 @@ func (b *executorBuilder) buildIndexLookUpReader(v *plannercore.PhysicalIndexLoo
 
 	ret.ranges = is.Ranges
 	executorCounterIndexLookUpExecutor.Inc()
+
 	sctx := b.ctx.GetSessionVars().StmtCtx
 	sctx.IndexNames = append(sctx.IndexNames, is.Table.Name.O+":"+is.Index.Name.O)
 	sctx.TableIDs = append(sctx.TableIDs, ts.Table.ID)
@@ -2908,6 +2909,8 @@ func (b *executorBuilder) buildBatchPointGet(plan *plannercore.BatchPointGetPlan
 		idxInfo:      plan.IndexInfo,
 		rowDecoder:   decoder,
 		startTS:      startTS,
+		keepOrder:    plan.KeepOrder,
+		desc:         plan.Desc,
 		lock:         plan.Lock,
 		waitTime:     plan.LockWaitTime,
 	}

executor/executor_test.go

@@ -2090,7 +2090,7 @@ func (s *testSuiteP2) TestIsPointGet(c *C) {
 	ctx := tk.Se.(sessionctx.Context)
 	tests := map[string]bool{
 		"select * from help_topic where name='aaa'":         false,
-		"select 1 from help_topic where name='aaa'":         true,
+		"select 1 from help_topic where name='aaa'":         false,
 		"select * from help_topic where help_topic_id=1":    true,
 		"select * from help_topic where help_category_id=1": false,
 	}

expression/testdata/partition_pruner_out.json

@@ -5,9 +5,8 @@
       {
         "SQL": "explain select * from t1 where id = 7 and a = 6",
         "Result": [
-          "TableReader_8 0.00 root data:Selection_7",
-          "└─Selection_7 0.00 cop[tikv] eq(test_partition.t1.a, 6)",
-          "  └─TableRangeScan_6 1.00 cop[tikv] table:t1, partition:p7, range:[7,7], keep order:false, stats:pseudo"
+          "Selection_7 0.00 root eq(test_partition.t1.a, 6)",
+          "└─Point_Get_6 1.00 root table:t1, handle:7, partition:p7"
         ]
       },
       {
@@ -19,16 +18,13 @@
       {
         "SQL": "explain select * from t2 where id = 9 and a = -110",
         "Result": [
-          "IndexLookUp_8 1.00 root ",
-          "├─IndexRangeScan_6(Build) 1.00 cop[tikv] table:t2, partition:p1, index:id, a, range:[9 -110,9 -110], keep order:false, stats:pseudo",
-          "└─TableRowIDScan_7(Probe) 1.00 cop[tikv] table:t2, partition:p1, keep order:false, stats:pseudo"
+          "Point_Get_6 1.00 root table:t2, index:id a, partition:p1"
         ]
       },
       {
         "SQL": "explain select * from t1 where id = -17",
         "Result": [
-          "TableReader_7 1.00 root data:TableRangeScan_6",
-          "└─TableRangeScan_6 1.00 cop[tikv] table:t1, partition:p7, range:[-17,-17], keep order:false, stats:pseudo"
+          "Point_Get_6 1.00 root table:t1, handle:-17, partition:p7"
         ]
       },
       {
@@ -42,34 +38,25 @@
       {
         "SQL": "explain select * from t1 join t2 on (t1.id = t2.id) where t1.id = 5 and t2.a = 7",
         "Result": [
-          "HashLeftJoin_10 1.00 root CARTESIAN inner join, inner:IndexLookUp_16",
-          "├─IndexLookUp_16(Build) 1.00 root ",
-          "│ ├─IndexRangeScan_14(Build) 1.00 cop[tikv] table:t2, partition:p2, index:id, a, range:[5 7,5 7], keep order:false, stats:pseudo",
-          "│ └─TableRowIDScan_15(Probe) 1.00 cop[tikv] table:t2, partition:p2, keep order:false, stats:pseudo",
-          "└─TableReader_13(Probe) 1.00 root data:TableRangeScan_12",
-          "  └─TableRangeScan_12 1.00 cop[tikv] table:t1, partition:p5, range:[5,5], keep order:false, stats:pseudo"
+          "HashLeftJoin_10 1.00 root CARTESIAN inner join, inner:Point_Get_13",
+          "├─Point_Get_13(Build) 1.00 root table:t2, index:id a, partition:p2",
+          "└─Point_Get_12(Probe) 1.00 root table:t1, handle:5, partition:p5"
         ]
       },
       {
         "SQL": "explain select * from t1 left join t2 on t1.id = 1 and t2.a = 2 where t2.id = 7",
         "Result": [
-          "HashLeftJoin_9 1.00 root CARTESIAN inner join, inner:IndexLookUp_15",
-          "├─IndexLookUp_15(Build) 1.00 root ",
-          "│ ├─IndexRangeScan_13(Build) 1.00 cop[tikv] table:t2, partition:p9, index:id, a, range:[7 2,7 2], keep order:false, stats:pseudo",
-          "│ └─TableRowIDScan_14(Probe) 1.00 cop[tikv] table:t2, partition:p9, keep order:false, stats:pseudo",
-          "└─TableReader_12(Probe) 1.00 root data:TableRangeScan_11",
-          "  └─TableRangeScan_11 1.00 cop[tikv] table:t1, partition:p1, range:[1,1], keep order:false, stats:pseudo"
+          "HashLeftJoin_9 1.00 root CARTESIAN inner join, inner:Point_Get_12",
+          "├─Point_Get_12(Build) 1.00 root table:t2, index:id a, partition:p9",
+          "└─Point_Get_11(Probe) 1.00 root table:t1, handle:1, partition:p1"
         ]
       },
       {
         "SQL": "explain select * from t2 join t1 on t1.id = t2.id and t2.a = t1.id and t2.id = 12",
         "Result": [
-          "HashLeftJoin_9 1.00 root CARTESIAN inner join, inner:TableReader_15",
-          "├─TableReader_15(Build) 1.00 root data:TableRangeScan_14",
-          "│ └─TableRangeScan_14 1.00 cop[tikv] table:t1, partition:p2, range:[12,12], keep order:false, stats:pseudo",
-          "└─IndexLookUp_13(Probe) 1.00 root ",
-          "  ├─IndexRangeScan_11(Build) 1.00 cop[tikv] table:t2, partition:p4, index:id, a, range:[12 12,12 12], keep order:false, stats:pseudo",
-          "  └─TableRowIDScan_12(Probe) 1.00 cop[tikv] table:t2, partition:p4, keep order:false, stats:pseudo"
+          "HashLeftJoin_9 1.00 root CARTESIAN inner join, inner:Point_Get_12",
+          "├─Point_Get_12(Build) 1.00 root table:t1, handle:12, partition:p2",
+          "└─Point_Get_11(Probe) 1.00 root table:t2, index:id a, partition:p4"
         ]
       },
       {