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address comments:
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- rename isnull to hasNull
- add comments
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@eurekaka
eurekaka committed Dec 25, 2018
1 parent 4abb4cb commit a5c4f95
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Showing 2 changed files with 33 additions and 25 deletions.
47 changes: 26 additions & 21 deletions executor/joiner.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -35,14 +35,15 @@ var (
// joiner is used to generate join results according to the join type.
// A typical instruction flow is:
//
// hasMatch := false
// hasMatch, hasNull := false, false
// for innerIter.Current() != innerIter.End() {
// matched, err := j.tryToMatch(outer, innerIter, chk)
// matched, isNull, err := j.tryToMatch(outer, innerIter, chk)
// // handle err
// hasMatch = hasMatch || matched
// hasNull = hasNull || isNull
// }
// if !hasMatch {
// j.onMissMatch(outer)
// j.onMissMatch(hasNull, outer, chk)
// }
//
// NOTE: This interface is **not** thread-safe.
Expand Down Expand Up @@ -76,7 +77,11 @@ type joiner interface {
// 6. 'RightOuterJoin': concats the unmatched outer row with a row of NULLs
// and appends it to the result buffer.
// 7. 'InnerJoin': ignores the unmatched outer row.
onMissMatch(isnull bool, outer chunk.Row, chk *chunk.Chunk)
// Not that, for anti join, we need to know the reason of outer row treated as
// unmatched: whether the join condition returns false, or returns null, because
// it decides if this outer row should be outputed, hence we have a `hasNull`
// parameter passed to `onMissMatch`.
onMissMatch(hasNull bool, outer chunk.Row, chk *chunk.Chunk)
}

func newJoiner(ctx sessionctx.Context, joinType plannercore.JoinType,
Expand Down Expand Up @@ -176,7 +181,7 @@ type semiJoiner struct {
baseJoiner
}

func (j *semiJoiner) tryToMatch(outer chunk.Row, inners chunk.Iterator, chk *chunk.Chunk) (matched bool, isnull bool, err error) {
func (j *semiJoiner) tryToMatch(outer chunk.Row, inners chunk.Iterator, chk *chunk.Chunk) (matched bool, hasNull bool, err error) {
if inners.Len() == 0 {
return false, false, nil
}
Expand All @@ -203,15 +208,15 @@ func (j *semiJoiner) tryToMatch(outer chunk.Row, inners chunk.Iterator, chk *chu
return false, false, nil
}

func (j *semiJoiner) onMissMatch(isnull bool, outer chunk.Row, chk *chunk.Chunk) {
func (j *semiJoiner) onMissMatch(hasNull bool, outer chunk.Row, chk *chunk.Chunk) {
}

type antiSemiJoiner struct {
baseJoiner
}

// tryToMatch implements joiner interface.
func (j *antiSemiJoiner) tryToMatch(outer chunk.Row, inners chunk.Iterator, chk *chunk.Chunk) (matched bool, isnull bool, err error) {
func (j *antiSemiJoiner) tryToMatch(outer chunk.Row, inners chunk.Iterator, chk *chunk.Chunk) (matched bool, hasNull bool, err error) {
if inners.Len() == 0 {
return false, false, nil
}
Expand All @@ -232,13 +237,13 @@ func (j *antiSemiJoiner) tryToMatch(outer chunk.Row, inners chunk.Iterator, chk
inners.ReachEnd()
return true, false, nil
}
isnull = isnull || isNull
hasNull = hasNull || isNull
}
return false, isnull, nil
return false, hasNull, nil
}

func (j *antiSemiJoiner) onMissMatch(isnull bool, outer chunk.Row, chk *chunk.Chunk) {
if !isnull {
func (j *antiSemiJoiner) onMissMatch(hasNull bool, outer chunk.Row, chk *chunk.Chunk) {
if !hasNull {
chk.AppendRow(outer)
}
}
Expand All @@ -248,7 +253,7 @@ type leftOuterSemiJoiner struct {
}

// tryToMatch implements joiner interface.
func (j *leftOuterSemiJoiner) tryToMatch(outer chunk.Row, inners chunk.Iterator, chk *chunk.Chunk) (matched bool, isnull bool, err error) {
func (j *leftOuterSemiJoiner) tryToMatch(outer chunk.Row, inners chunk.Iterator, chk *chunk.Chunk) (matched bool, hasNull bool, err error) {
if inners.Len() == 0 {
return false, false, nil
}
Expand Down Expand Up @@ -280,7 +285,7 @@ func (j *leftOuterSemiJoiner) onMatch(outer chunk.Row, chk *chunk.Chunk) {
chk.AppendInt64(outer.Len(), 1)
}

func (j *leftOuterSemiJoiner) onMissMatch(isnull bool, outer chunk.Row, chk *chunk.Chunk) {
func (j *leftOuterSemiJoiner) onMissMatch(hasNull bool, outer chunk.Row, chk *chunk.Chunk) {
chk.AppendPartialRow(0, outer)
chk.AppendInt64(outer.Len(), 0)
}
Expand All @@ -290,7 +295,7 @@ type antiLeftOuterSemiJoiner struct {
}

// tryToMatch implements joiner interface.
func (j *antiLeftOuterSemiJoiner) tryToMatch(outer chunk.Row, inners chunk.Iterator, chk *chunk.Chunk) (matched bool, isnull bool, err error) {
func (j *antiLeftOuterSemiJoiner) tryToMatch(outer chunk.Row, inners chunk.Iterator, chk *chunk.Chunk) (matched bool, hasNull bool, err error) {
if inners.Len() == 0 {
return false, false, nil
}
Expand All @@ -313,19 +318,19 @@ func (j *antiLeftOuterSemiJoiner) tryToMatch(outer chunk.Row, inners chunk.Itera
inners.ReachEnd()
return true, false, nil
}
isnull = isnull || isNull
hasNull = hasNull || isNull
}
return false, isnull, nil
return false, hasNull, nil
}

func (j *antiLeftOuterSemiJoiner) onMatch(outer chunk.Row, chk *chunk.Chunk) {
chk.AppendPartialRow(0, outer)
chk.AppendInt64(outer.Len(), 0)
}

func (j *antiLeftOuterSemiJoiner) onMissMatch(isnull bool, outer chunk.Row, chk *chunk.Chunk) {
func (j *antiLeftOuterSemiJoiner) onMissMatch(hasNull bool, outer chunk.Row, chk *chunk.Chunk) {
chk.AppendPartialRow(0, outer)
if isnull {
if hasNull {
chk.AppendInt64(outer.Len(), 0)
} else {
chk.AppendInt64(outer.Len(), 1)
Expand Down Expand Up @@ -364,7 +369,7 @@ func (j *leftOuterJoiner) tryToMatch(outer chunk.Row, inners chunk.Iterator, chk
return matched, false, nil
}

func (j *leftOuterJoiner) onMissMatch(isnull bool, outer chunk.Row, chk *chunk.Chunk) {
func (j *leftOuterJoiner) onMissMatch(hasNull bool, outer chunk.Row, chk *chunk.Chunk) {
chk.AppendPartialRow(0, outer)
chk.AppendPartialRow(outer.Len(), j.defaultInner)
}
Expand Down Expand Up @@ -401,7 +406,7 @@ func (j *rightOuterJoiner) tryToMatch(outer chunk.Row, inners chunk.Iterator, ch
return matched, false, nil
}

func (j *rightOuterJoiner) onMissMatch(isnull bool, outer chunk.Row, chk *chunk.Chunk) {
func (j *rightOuterJoiner) onMissMatch(hasNull bool, outer chunk.Row, chk *chunk.Chunk) {
chk.AppendPartialRow(0, j.defaultInner)
chk.AppendPartialRow(j.defaultInner.Len(), outer)
}
Expand Down Expand Up @@ -441,5 +446,5 @@ func (j *innerJoiner) tryToMatch(outer chunk.Row, inners chunk.Iterator, chk *ch

}

func (j *innerJoiner) onMissMatch(isnull bool, outer chunk.Row, chk *chunk.Chunk) {
func (j *innerJoiner) onMissMatch(hasNull bool, outer chunk.Row, chk *chunk.Chunk) {
}
11 changes: 7 additions & 4 deletions expression/expression.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -111,16 +111,19 @@ func (e CNFExprs) Clone() CNFExprs {
return cnf
}

// EvalBool evaluates expression list to a boolean value.
// EvalBool evaluates expression list to a boolean value. The first returned value
// indicates bool result of the expression list, the second returned value indicates
// whether the result of the expression list is null, it can only be true when the
// first returned values is false.
func EvalBool(ctx sessionctx.Context, exprList CNFExprs, row chunk.Row) (bool, bool, error) {
isnull := false
hasNull := false
for _, expr := range exprList {
data, err := expr.Eval(row)
if err != nil {
return false, false, err
}
if data.IsNull() {
isnull = true
hasNull = true
continue
}

Expand All @@ -132,7 +135,7 @@ func EvalBool(ctx sessionctx.Context, exprList CNFExprs, row chunk.Row) (bool, b
return false, false, nil
}
}
if isnull {
if hasNull {
return false, true, nil
}
return true, false, nil
Expand Down

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