planner, executor: push limit down into IndexLookUpReader executor #12262
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eurekaka
added
type/enhancement
Codecov Report
@@ Coverage Diff @@
## master #12262 +/- ##
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Coverage 81.1502% 81.1502%
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Files 454 454
Lines 99662 99662
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Hits 80876 80876
Misses 12972 12972
Partials 5814 5814 |
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/run-all-tests |
eurekaka
requested review from
francis0407,
winoros,
zz-jason,
XuHuaiyu,
SunRunAway,
alivxxx and
lzmhhh123
|
This pr seems to do some query-rewrite in cbo pahse? |
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@jingyugao Yes, it is query-rewrite to some extent, like the operator pushdown (to storage layer) here. |
alivxxx
reviewed
Sep 23, 2019
francis0407
reviewed
Sep 23, 2019
| @@ -484,9 +487,9 @@ func (e *IndexLookUpExecutor) startIndexWorker(ctx context.Context, kvRanges []k | |||
| } | |||
| if e.runtimeStats != nil { | |||
| copStats := e.ctx.GetSessionVars().StmtCtx.RuntimeStatsColl.GetRootStats(e.idxPlans[len(e.idxPlans)-1].ExplainID().String()) | |||
| copStats.SetRowNum(count) | |||
| copStats.SetRowNum(int64(count)) | |||
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Not related to this PR, but it seems really strange to use int64 instead of uint64 for a count.
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@qw4990 Is there any specific reason why we are using int/int64 for SetRequiredRows/SetRowNum respectively?
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For RowNum, we use methods like atomic.XXXInt64 to maintain it so its type is int64.
And for RequiredRows we maintain it using Golang statement and for convenience, we set its type to int.
zz-jason
reviewed
Sep 23, 2019
zz-jason
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needs-cherry-pick-2.1
status/LGT2
zz-jason
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zz-jason
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the
status/can-merge
|
Your auto merge job has been accepted, waiting for 12331, 12332, 12325 |
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/run-all-tests |
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/run-all-tests |
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cherry pick to release-3.1 failed |
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cherry pick to release-3.0 failed |
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cherry pick to release-2.1 failed |
eurekaka
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Sep 25, 2019
…ingcap#12262) Conflicts: cmd/explaintest/r/explain_easy.result cmd/explaintest/r/explain_easy_stats.result planner/core/integration_test.go planner/core/physical_plans.go planner/core/testdata/plan_suite_out.json
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eurekaka
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…ingcap#12262) Conflicts: cmd/explaintest/r/explain_easy.result cmd/explaintest/r/explain_easy_stats.result planner/core/integration_test.go planner/core/physical_plans.go planner/core/testdata/plan_suite_out.json
eurekaka
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…ingcap#12262) Conflicts: cmd/explaintest/r/explain_easy.result cmd/explaintest/r/explain_easy_stats.result planner/core/integration_test.go planner/core/physical_plans.go planner/core/testdata/plan_suite_out.json executor/distsql.go executor/distsql_test.go
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What problem does this PR solve?
Fix #10668
What is changed and how it works?
Sink
PhysicalLimiton top ofIndexLookUpReaderintoIndexLookUpReader, and in executor, skip the preceding and tailing handles returned byIndexPlan. This optimization can avoid unnecessaryTableScanfor handles not satisfyingLimit / Offsetconstraint, and improve execution performance especially for queries with largeOffset.Check List
Tests
Code changes
Side effects
Related changes
IndexLookUpReader'sTablePlan / IndexPlansince some unnecessary I/O and network cost is avoided. This can be done in the next PR.