executor: add batch copy to inner join, left and right outer join.

executor/joiner.go

@@ -164,7 +164,7 @@ func (j *baseJoiner) filter(input, output *chunk.Chunk, outerColsLen int) (bool,
 	if err != nil {
 		return false, errors.Trace(err)
 	}
-	// batch copy selected row to output chunk
+	// Batch copies selected rows to output chunk.
 	innerColOffset, outerColOffset := 0, input.NumCols()-outerColsLen
 	if !j.outerIsRight {
 		innerColOffset, outerColOffset = outerColsLen, 0

util/chunk/chunk_util.go

@@ -15,6 +15,7 @@ package chunk
 
 // CopySelectedJoinRows copies the selected joined rows from the source Chunk
 // to the destination Chunk.
+// Return true if at least one joined row was selected.
 //
 // NOTE: All the outer rows in the source Chunk should be the same.
 func CopySelectedJoinRows(src *Chunk, innerColOffset, outerColOffset int, selected []bool, dst *Chunk) bool {

util/chunk/column.go

@@ -72,40 +72,43 @@ func (c *column) isNull(rowIdx int) bool {
 	return nullByte&(1<<(uint(rowIdx)&7)) == 0
 }
 
-func (c *column) appendNullBitmap(on bool) {
+func (c *column) appendNullBitmap(notNull bool) {
 	idx := c.length >> 3
 	if idx >= len(c.nullBitmap) {
 		c.nullBitmap = append(c.nullBitmap, 0)
 	}
-	if on {
+	if notNull {
 		pos := uint(c.length) & 7
 		c.nullBitmap[idx] |= byte(1 << pos)
 	} else {
 		c.nullCount++
 	}
 }
 
-func (c *column) appendMultiSameNullBitmap(on bool, num int) {
+// appendMultiSameNullBitmap appends multiple same bit value to `nullBitMap`.
+// notNull mean not not null.
+// num mean appends `num` bit value to `nullBitMap`.
+func (c *column) appendMultiSameNullBitmap(notNull bool, num int) {
 	numNewBytes := ((c.length + num + 7) >> 3) - len(c.nullBitmap)
 	b := byte(0)
-	if on {
+	if notNull {
 		b = 0xff
 	}
 	for i := 0; i < numNewBytes; i++ {
 		c.nullBitmap = append(c.nullBitmap, b)
 	}
-	if on {
-		// 1. Set all the higher 8-'numOldBits' bits in the last old byte to 1.
-		numOldBits := uint(c.length % 8)
-		bitMask := byte(^((1 << numOldBits) - 1))
-		c.nullBitmap[c.length/8] |= bitMask
-		// 2. Set all the higher 'numRedundantBits' bits in the last new byte to 0.
-		numRedundantBits := uint(len(c.nullBitmap)*8 - c.length - num)
-		bitMask = byte(1<<(8-numRedundantBits)) - 1
-		c.nullBitmap[len(c.nullBitmap)-1] &= bitMask
-	} else {
+	if !notNull {
 		c.nullCount += num
+		return
 	}
+	// 1. Set all the higher 8-'numOldBits' bits in the last old byte to 1.
+	numOldBits := uint(c.length % 8)
+	bitMask := byte(^((1 << numOldBits) - 1))
+	c.nullBitmap[c.length/8] |= bitMask
+	// 2. Set all the higher 'numRedundantBits' bits in the last new byte to 0.
+	numRedundantBits := uint(len(c.nullBitmap)*8 - c.length - num)
+	bitMask = byte(1<<(8-numRedundantBits)) - 1
+	c.nullBitmap[len(c.nullBitmap)-1] &= bitMask
 }
 
 func (c *column) appendNull() {