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plan: address comment.

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This commit is contained in:
Ewan Chou
2015-11-11 18:33:43 +08:00
parent 2d36bc727b
commit 59e1187f18
1 changed files with 16 additions and 16 deletions
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32
plan/plans/index.go
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@ -328,21 +328,21 @@ func toSpans(op opcode.Op, val, seekVal interface{}) []*indexSpan {
}
// Next implements plan.Plan Next interface.
func (r *indexPlan) Next(ctx context.Context) (row *plan.Row, err error) {
func (r *indexPlan) Next(ctx context.Context) (*plan.Row, error) {
for {
if r.cursor == len(r.spans) {
return
return nil, nil
}
span := r.spans[r.cursor]
if r.isPointLookup(span) {
// Do point lookup on index will prevent prefetch cost.
row, err = r.pointLookup(ctx, span.lowVal)
row, err := r.pointLookup(ctx, span.lowVal)
if err != nil {
return nil, errors.Trace(err)
}
r.cursor++
if row != nil {
return
return row, nil
}
continue
}
@ -352,7 +352,7 @@ func (r *indexPlan) Next(ctx context.Context) (row *plan.Row, err error) {
seekVal = []byte{}
}
var txn kv.Transaction
txn, err = ctx.GetTxn(false)
txn, err := ctx.GetTxn(false)
if err != nil {
return nil, errors.Trace(err)
}
@ -361,9 +361,7 @@ func (r *indexPlan) Next(ctx context.Context) (row *plan.Row, err error) {
return nil, types.EOFAsNil(err)
}
}
var idxKey []interface{}
var h int64
idxKey, h, err = r.iter.Next()
idxKey, h, err := r.iter.Next()
if err != nil {
return nil, types.EOFAsNil(err)
}
@ -385,11 +383,12 @@ func (r *indexPlan) Next(ctx context.Context) (row *plan.Row, err error) {
r.skipLowCmp = false
continue
}
var row *plan.Row
row, err = r.lookupRow(ctx, h)
if err != nil {
return nil, errors.Trace(err)
}
return
return row, nil
}
}
@ -397,8 +396,9 @@ func (r *indexPlan) isPointLookup(span *indexSpan) bool {
return r.unique && span.lowVal != nil && span.lowVal == span.highVal && !span.lowExclude && !span.highExclude
}
func (r *indexPlan) lookupRow(ctx context.Context, h int64) (row *plan.Row, err error) {
row = &plan.Row{}
func (r *indexPlan) lookupRow(ctx context.Context, h int64) (*plan.Row, error) {
row := &plan.Row{}
var err error
row.Data, err = r.src.Row(ctx, h)
if err != nil {
return nil, errors.Trace(err)
@ -408,13 +408,12 @@ func (r *indexPlan) lookupRow(ctx context.Context, h int64) (row *plan.Row, err
Key: string(r.src.RecordKey(h, nil)),
}
row.RowKeys = append(row.RowKeys, rowKey)
return
return row, nil
}
// pointLookup do not seek index but call Exists method to get a handle, which is cheaper.
func (r *indexPlan) pointLookup(ctx context.Context, val interface{}) (row *plan.Row, err error) {
var txn kv.Transaction
txn, err = ctx.GetTxn(false)
func (r *indexPlan) pointLookup(ctx context.Context, val interface{}) (*plan.Row, error) {
txn, err := ctx.GetTxn(false)
if err != nil {
return nil, errors.Trace(err)
}
@ -428,11 +427,12 @@ func (r *indexPlan) pointLookup(ctx context.Context, val interface{}) (row *plan
if terror.ErrorNotEqual(kv.ErrKeyExists, err) {
return nil, errors.Trace(err)
}
var row *plan.Row
row, err = r.lookupRow(ctx, h)
if err != nil {
return nil, errors.Trace(err)
}
return
return row, nil
}
// Close implements plan.Plan Close interface.