executor: vectorize the merge join executor by vecGroupChecker

executor/aggregate.go

@@ -1035,6 +1035,7 @@ func (e *vecGroupChecker) splitIntoGroups(chk *chunk.Chunk) (isFirstGroupSameAsP
 	e.nextGroupID = 0
 	if len(e.GroupByItems) == 0 {
 		e.groupOffset = append(e.groupOffset, numRows)
+		e.groupCount = 1
 		return true, nil
 	}
 

executor/benchmark_test.go

@@ -1280,17 +1280,16 @@ func prepare4MergeJoin(tc *mergeJoinTestCase, leftExec, rightExec *mockDataSourc
 		isOuterJoin: false,
 	}
 
-	e.outerIdx = 0
-
-	e.innerTable = &mergeJoinInnerTable{
-		reader:   rightExec,
-		joinKeys: innerJoinKeys,
+	e.innerTable = &mergeJoinTable{
+		isInner:    true,
+		childIndex: 1,
+		joinKeys:   innerJoinKeys,
 	}
 
-	e.outerTable = &mergeJoinOuterTable{
-		reader: leftExec,
-		filter: nil,
-		keys:   outerJoinKeys,
+	e.outerTable = &mergeJoinTable{
+		childIndex: 0,
+		filters:    nil,
+		joinKeys:   outerJoinKeys,
 	}
 
 	return e

executor/builder.go

@@ -985,37 +985,29 @@ func (b *executorBuilder) buildMergeJoin(v *plannercore.PhysicalMergeJoin) Execu
 		desc:        v.Desc,
 	}
 
-	leftKeys := v.LeftJoinKeys
-	rightKeys := v.RightJoinKeys
-
-	e.outerIdx = 0
-	innerFilter := v.RightConditions
-
-	e.innerTable = &mergeJoinInnerTable{
-		reader:   rightExec,
-		joinKeys: rightKeys,
+	leftTable := &mergeJoinTable{
+		childIndex: 0,
+		joinKeys:   v.LeftJoinKeys,
+		filters:    v.LeftConditions,
 	}
-
-	e.outerTable = &mergeJoinOuterTable{
-		reader: leftExec,
-		filter: v.LeftConditions,
-		keys:   leftKeys,
+	rightTable := &mergeJoinTable{
+		childIndex: 1,
+		joinKeys:   v.RightJoinKeys,
+		filters:    v.RightConditions,
 	}
 
 	if v.JoinType == plannercore.RightOuterJoin {
-		e.outerIdx = 1
-		e.outerTable.reader = rightExec
-		e.outerTable.filter = v.RightConditions
-		e.outerTable.keys = rightKeys
-
-		innerFilter = v.LeftConditions
-		e.innerTable.reader = leftExec
-		e.innerTable.joinKeys = leftKeys
+		e.innerTable = leftTable
+		e.outerTable = rightTable
+	} else {
+		e.innerTable = rightTable
+		e.outerTable = leftTable
 	}
+	e.innerTable.isInner = true
 
 	// optimizer should guarantee that filters on inner table are pushed down
 	// to tikv or extracted to a Selection.
-	if len(innerFilter) != 0 {
+	if len(e.innerTable.filters) != 0 {
 		b.err = errors.Annotate(ErrBuildExecutor, "merge join's inner filter should be empty.")
 		return nil
 	}