plan: always chose the smaller child as outer for IndexJoin #6996
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
winoros
added
status/LGT1
shenli
reviewed
Jul 5, 2018
plan/plan.go
Outdated
| @@ -320,6 +323,13 @@ type basePlan struct { | |||
| stats *statsInfo | |||
| } | |||
|
|
|||
| func (p *basePlan) cardinality() float64 { | |||
| if p.stats == nil { | |||
| return math.MaxFloat64 | |||
| @@ -163,6 +164,8 @@ type LogicalPlan interface { | |||
| // deriveStats derives statistic info between plans. | |||
| deriveStats() (*statsInfo, error) | |||
|
|
|||
| cardinality() float64 | |||
| @@ -385,22 +385,30 @@ func (p *LogicalJoin) tryToGetIndexJoin(prop *requiredProp) ([]PhysicalPlan, boo | |||
| plans = append(plans, join...) | |||
| } | |||
| case InnerJoin: | |||
| join := p.getIndexJoinByOuterIdx(prop, 0) | |||
| if join != nil { | |||
| lhsCardinality := p.Children()[0].cardinality() | |||
alivxxx
reviewed
Jul 5, 2018
| if p.stats == nil { | ||
| return math.MaxFloat64 | ||
| } | ||
| return p.stats.count |
There was a problem hiding this comment.
It is not cardinality, cardinality is the number of elements in a set.
coocood
reviewed
Jul 5, 2018
| @@ -163,6 +164,8 @@ type LogicalPlan interface { | |||
| // deriveStats derives statistic info between plans. | |||
| deriveStats() (*statsInfo, error) | |||
|
|
|||
| cardinality() float64 | |||
There was a problem hiding this comment.
Can we add getStats instead?
Then use the count to determine the outer table.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
What have you changed? (mandatory)
Always chose the smaller child as the outer one for
IndexJoinif possible.What are the type of the changes (mandatory)?
How has this PR been tested (mandatory)?