executor: optimize (left outer) (anti) semi join which has no other condition

pkg/executor/cte.go

@@ -633,13 +633,14 @@ func (p *cteProducer) checkHasDup(probeKey uint64,
 	curChk *chunk.Chunk,
 	storage cteutil.Storage,
 	hashTbl baseHashTable) (hasDup bool, err error) {
-	ptrs := hashTbl.Get(probeKey)
+	entry := hashTbl.Get(probeKey)
 
-	if len(ptrs) == 0 {
+	if entry == nil {
 		return false, nil
 	}
 
-	for _, ptr := range ptrs {
+	for ; entry != nil; entry = entry.next {
+		ptr := entry.ptr
 		var matchedRow chunk.Row
 		if curChk != nil {
 			matchedRow = curChk.GetRow(int(ptr.RowIdx))

pkg/executor/hash_table.go

@@ -152,6 +152,47 @@ func (c *hashRowContainer) GetMatchedRows(probeKey uint64, probeRow chunk.Row, h
 	return matchedRows, err
 }
 
+// GetOneMatchedRow get one matched rows from probeRow.
+func (c *hashRowContainer) GetOneMatchedRow(probeKey uint64, probeRow chunk.Row, hCtx *hashContext) (*chunk.Row, error) {
+	var err error
+	innerEntry := c.hashTable.Get(probeKey)
+	if innerEntry == nil {
+		return nil, err
+	}
+	var matchedRow chunk.Row
+
+	if c.chkBuf != nil {
+		c.chkBuf.Reset()
+	}
+	capacity := 0
+
+	for i := 0; innerEntry != nil; i, innerEntry = i+1, innerEntry.next {
+		ptr := innerEntry.ptr
+		matchedRow, c.chkBuf, err = c.rowContainer.GetRowAndAppendToChunkIfInDisk(ptr, c.chkBuf)
+		if err != nil {
+			return nil, err
+		}
+		var ok bool
+		ok, err = c.matchJoinKey(matchedRow, probeRow, hCtx)
+		if err != nil {
+			return nil, err
+		}
+		if ok {
+			return &matchedRow, nil
+		}
+		atomic.AddInt64(&c.stat.probeCollision, 1)
+		if i == 0 {
+			capacity = c.chkBuf.Capacity()
+			if capacity < 128 {
+				capacity = 128
+			}
+		} else if (i+1)%capacity == 0 {
+			c.chkBuf.Reset()
+		}
+	}
+	return nil, err
+}
+
 func (c *hashRowContainer) GetAllMatchedRows(probeHCtx *hashContext, probeSideRow chunk.Row,
 	probeKeyNullBits *bitmap.ConcurrentBitmap, matched []chunk.Row, needCheckBuildColPos, needCheckProbeColPos []int, needCheckBuildTypes, needCheckProbeTypes []*types.FieldType) ([]chunk.Row, error) {
 	// for NAAJ probe row with null, we should match them with all build rows.
@@ -232,7 +273,12 @@ const rowPtrSize = int64(unsafe.Sizeof(chunk.RowPtr{}))
 // h and buf.
 func (c *hashRowContainer) GetMatchedRowsAndPtrs(probeKey uint64, probeRow chunk.Row, hCtx *hashContext, matched []chunk.Row, matchedPtrs []chunk.RowPtr, needPtr bool) ([]chunk.Row, []chunk.RowPtr, error) {
 	var err error
-	innerPtrs := c.hashTable.Get(probeKey)
+	innerEntry := c.hashTable.Get(probeKey)
+	var innerPtrs []chunk.RowPtr
+	for innerEntry != nil {
+		innerPtrs = append(innerPtrs, innerEntry.ptr)
+		innerEntry = innerEntry.next
+	}
 	if len(innerPtrs) == 0 {
 		return nil, nil, err
 	}
@@ -565,7 +611,7 @@ func (es *entryStore) GetStore() (e *entry, memDelta int64) {
 
 type baseHashTable interface {
 	Put(hashKey uint64, rowPtr chunk.RowPtr)
-	Get(hashKey uint64) (rowPtrs []chunk.RowPtr)
+	Get(hashKey uint64) *entry
 	Len() uint64
 	// GetAndCleanMemoryDelta gets and cleans the memDelta of the baseHashTable. Memory delta will be cleared after each fetch.
 	// It indicates the memory delta of the baseHashTable since the last calling GetAndCleanMemoryDelta().
@@ -611,13 +657,9 @@ func (ht *unsafeHashTable) Put(hashKey uint64, rowPtr chunk.RowPtr) {
 }
 
 // Get gets the values of the "key" and appends them to "values".
-func (ht *unsafeHashTable) Get(hashKey uint64) (rowPtrs []chunk.RowPtr) {
+func (ht *unsafeHashTable) Get(hashKey uint64) *entry {
 	entryAddr := ht.hashMap[hashKey]
-	for entryAddr != nil {
-		rowPtrs = append(rowPtrs, entryAddr.ptr)
-		entryAddr = entryAddr.next
-	}
-	return
+	return entryAddr
 }
 
 // Len returns the number of rowPtrs in the unsafeHashTable, the number of keys may be less than Len
@@ -674,13 +716,9 @@ func (ht *concurrentMapHashTable) Put(hashKey uint64, rowPtr chunk.RowPtr) {
 }
 
 // Get gets the values of the "key" and appends them to "values".
-func (ht *concurrentMapHashTable) Get(hashKey uint64) (rowPtrs []chunk.RowPtr) {
+func (ht *concurrentMapHashTable) Get(hashKey uint64) *entry {
 	entryAddr, _ := ht.hashMap.Get(hashKey)
-	for entryAddr != nil {
-		rowPtrs = append(rowPtrs, entryAddr.ptr)
-		entryAddr = entryAddr.next
-	}
-	return
+	return entryAddr
 }
 
 // Iter gets the every value of the hash table.

pkg/executor/index_lookup_hash_join.go

@@ -87,7 +87,6 @@ type indexHashJoinOuterWorker struct {
 
 type indexHashJoinInnerWorker struct {
 	innerWorker
-	matchedOuterPtrs  []chunk.RowPtr
 	joiner            joiner
 	joinChkResourceCh chan *chunk.Chunk
 	// resultCh is valid only when indexNestedLoopHashJoin do not need to keep
@@ -436,7 +435,6 @@ func (e *IndexNestedLoopHashJoin) newInnerWorker(taskCh chan *indexHashJoinTask,
 		joiner:            e.joiners[workerID],
 		joinChkResourceCh: e.joinChkResourceCh[workerID],
 		resultCh:          e.resultCh,
-		matchedOuterPtrs:  make([]chunk.RowPtr, 0, e.MaxChunkSize()),
 		joinKeyBuf:        make([]byte, 1),
 		outerRowStatus:    make([]outerRowStatusFlag, 0, e.MaxChunkSize()),
 		rowIter:           chunk.NewIterator4Slice([]chunk.Row{}).(*chunk.Iterator4Slice),
@@ -712,15 +710,14 @@ func (iw *indexHashJoinInnerWorker) getMatchedOuterRows(innerRow chunk.Row, task
 	if err != nil {
 		return nil, nil, err
 	}
-	iw.matchedOuterPtrs = task.lookupMap.Get(h.Sum64())
-	if len(iw.matchedOuterPtrs) == 0 {
+	matchedOuterEntry := task.lookupMap.Get(h.Sum64())
+	if matchedOuterEntry == nil {
 		return nil, nil, nil
 	}
 	joinType := JoinerType(iw.joiner)
 	isSemiJoin := joinType == plannercore.SemiJoin || joinType == plannercore.LeftOuterSemiJoin
-	matchedRows = make([]chunk.Row, 0, len(iw.matchedOuterPtrs))
-	matchedRowPtr = make([]chunk.RowPtr, 0, len(iw.matchedOuterPtrs))
-	for _, ptr := range iw.matchedOuterPtrs {
+	for ; matchedOuterEntry != nil; matchedOuterEntry = matchedOuterEntry.next {
+		ptr := matchedOuterEntry.ptr
 		outerRow := task.outerResult.GetRow(ptr)
 		ok, err := codec.EqualChunkRow(iw.ctx.GetSessionVars().StmtCtx, innerRow, iw.hashTypes, iw.hashCols, outerRow, iw.outerCtx.hashTypes, iw.outerCtx.hashCols)
 		if err != nil {

pkg/executor/join.go

@@ -925,8 +925,18 @@ func (w *probeWorker) joinNAAJMatchProbeSideRow2Chunk(probeKey uint64, probeKeyN
 func (w *probeWorker) joinMatchedProbeSideRow2Chunk(probeKey uint64, probeSideRow chunk.Row, hCtx *hashContext,
 	joinResult *hashjoinWorkerResult) (bool, *hashjoinWorkerResult) {
 	var err error
-	w.buildSideRows, err = w.rowContainerForProbe.GetMatchedRows(probeKey, probeSideRow, hCtx, w.buildSideRows)
-	buildSideRows := w.buildSideRows
+	var buildSideRows []chunk.Row
+	if w.joiner.isSemiJoinWithoutCondition() {
+		var rowPtr *chunk.Row
+		rowPtr, err = w.rowContainerForProbe.GetOneMatchedRow(probeKey, probeSideRow, hCtx)
+		if rowPtr != nil {
+			buildSideRows = append(buildSideRows, *rowPtr)
+		}
+	} else {
+		w.buildSideRows, err = w.rowContainerForProbe.GetMatchedRows(probeKey, probeSideRow, hCtx, w.buildSideRows)
+		buildSideRows = w.buildSideRows
+	}
+
 	if err != nil {
 		joinResult.err = err
 		return false, joinResult

pkg/executor/joiner.go

@@ -106,6 +106,11 @@ type joiner interface {
 	// parameter passed to `onMissMatch`.
 	onMissMatch(hasNull bool, outer chunk.Row, chk *chunk.Chunk)
 
+	// isSemiJoinWithoutCondition returns if it's a semi join and has no condition.
+	// If true, at most one matched row is needed to match inners, which can optimize a lot when
+	// there are a lot of matched rows.
+	isSemiJoinWithoutCondition() bool
+
 	// Clone deep copies a joiner.
 	Clone() joiner
 }
@@ -426,6 +431,10 @@ func (j *semiJoiner) tryToMatchOuters(outers chunk.Iterator, inner chunk.Row, ch
 
 func (*semiJoiner) onMissMatch(bool, chunk.Row, *chunk.Chunk) {}
 
+func (j *semiJoiner) isSemiJoinWithoutCondition() bool {
+	return len(j.conditions) == 0
+}
+
 // Clone implements joiner interface.
 func (j *semiJoiner) Clone() joiner {
 	return &semiJoiner{baseJoiner: j.baseJoiner.Clone()}
@@ -490,6 +499,10 @@ func (naaj *nullAwareAntiSemiJoiner) onMissMatch(_ bool, outer chunk.Row, chk *c
 	chk.AppendRowByColIdxs(outer, naaj.lUsed)
 }
 
+func (naaj *nullAwareAntiSemiJoiner) isSemiJoinWithoutCondition() bool {
+	return len(naaj.conditions) == 0
+}
+
 func (naaj *nullAwareAntiSemiJoiner) Clone() joiner {
 	return &nullAwareAntiSemiJoiner{baseJoiner: naaj.baseJoiner.Clone()}
 }
@@ -559,6 +572,10 @@ func (j *antiSemiJoiner) onMissMatch(hasNull bool, outer chunk.Row, chk *chunk.C
 	}
 }
 
+func (j *antiSemiJoiner) isSemiJoinWithoutCondition() bool {
+	return len(j.conditions) == 0
+}
+
 func (j *antiSemiJoiner) Clone() joiner {
 	return &antiSemiJoiner{baseJoiner: j.baseJoiner.Clone()}
 }
@@ -641,6 +658,10 @@ func (j *leftOuterSemiJoiner) onMissMatch(hasNull bool, outer chunk.Row, chk *ch
 	}
 }
 
+func (j *leftOuterSemiJoiner) isSemiJoinWithoutCondition() bool {
+	return len(j.conditions) == 0
+}
+
 func (j *leftOuterSemiJoiner) Clone() joiner {
 	return &leftOuterSemiJoiner{baseJoiner: j.baseJoiner.Clone()}
 }
@@ -713,8 +734,12 @@ func (*nullAwareAntiLeftOuterSemiJoiner) tryToMatchOuters(chunk.Iterator, chunk.
 	return nil, err
 }
 
+func (naal *nullAwareAntiLeftOuterSemiJoiner) isSemiJoinWithoutCondition() bool {
+	return len(naal.conditions) == 0
+}
+
 func (naal *nullAwareAntiLeftOuterSemiJoiner) Clone() joiner {
-	return &antiLeftOuterSemiJoiner{baseJoiner: naal.baseJoiner.Clone()}
+	return &nullAwareAntiLeftOuterSemiJoiner{baseJoiner: naal.baseJoiner.Clone()}
 }
 
 type antiLeftOuterSemiJoiner struct {
@@ -798,6 +823,10 @@ func (j *antiLeftOuterSemiJoiner) onMissMatch(hasNull bool, outer chunk.Row, chk
 	}
 }
 
+func (j *antiLeftOuterSemiJoiner) isSemiJoinWithoutCondition() bool {
+	return len(j.conditions) == 0
+}
+
 func (j *antiLeftOuterSemiJoiner) Clone() joiner {
 	return &antiLeftOuterSemiJoiner{baseJoiner: j.baseJoiner.Clone()}
 }
@@ -877,6 +906,10 @@ func (j *leftOuterJoiner) onMissMatch(_ bool, outer chunk.Row, chk *chunk.Chunk)
 	chk.AppendPartialRowByColIdxs(lWide, j.defaultInner, j.rUsed)
 }
 
+func (*leftOuterJoiner) isSemiJoinWithoutCondition() bool {
+	return false
+}
+
 func (j *leftOuterJoiner) Clone() joiner {
 	return &leftOuterJoiner{baseJoiner: j.baseJoiner.Clone()}
 }
@@ -952,6 +985,10 @@ func (j *rightOuterJoiner) onMissMatch(_ bool, outer chunk.Row, chk *chunk.Chunk
 	chk.AppendPartialRowByColIdxs(lWide, outer, j.rUsed)
 }
 
+func (*rightOuterJoiner) isSemiJoinWithoutCondition() bool {
+	return false
+}
+
 func (j *rightOuterJoiner) Clone() joiner {
 	return &rightOuterJoiner{baseJoiner: j.baseJoiner.Clone()}
 }
@@ -1035,6 +1072,10 @@ func (j *innerJoiner) tryToMatchOuters(outers chunk.Iterator, inner chunk.Row, c
 
 func (*innerJoiner) onMissMatch(bool, chunk.Row, *chunk.Chunk) {}
 
+func (*innerJoiner) isSemiJoinWithoutCondition() bool {
+	return false
+}
+
 func (j *innerJoiner) Clone() joiner {
 	return &innerJoiner{baseJoiner: j.baseJoiner.Clone()}
 }