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planner: recalculate as-of ts of staleread when plan is cached #43204

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merged 2 commits into from
Apr 20, 2023
Merged

planner: recalculate as-of ts of staleread when plan is cached #43204

merged 2 commits into from
Apr 20, 2023

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you06
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@you06 you06 commented Apr 19, 2023

What problem does this PR solve?

Issue Number: close #43044

Problem Summary:

What is changed and how it works?

Recalculate the snapshot ts for staleread when it's provided by as of statement.

Check List

Tests

  • Unit test
  • Integration test
  • Manual test (add detailed scripts or steps below)
  • No code

Side effects

  • Performance regression: Consumes more CPU
  • Performance regression: Consumes more Memory
  • Breaking backward compatibility

Documentation

  • Affects user behaviors
  • Contains syntax changes
  • Contains variable changes
  • Contains experimental features
  • Changes MySQL compatibility

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

Fix the bug that prepared staleread cannot read following changes.

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ti-chi-bot commented Apr 19, 2023 •
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[REVIEW NOTIFICATION]

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  • cfzjywxk
  • qw4990

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@ti-chi-bot ti-chi-bot added release-note Denotes a PR that will be considered when it comes time to generate release notes. size/M Denotes a PR that changes 30-99 lines, ignoring generated files. labels Apr 19, 2023
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you06 commented Apr 19, 2023

/retest

cfzjywxk
cfzjywxk reviewed Apr 19, 2023
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sessiontxn/staleread/processor.go
@@ -179,7 +182,7 @@ func (p *staleReadProcessor) OnSelectTable(tn *ast.TableName) error {
}
return nil
}
return p.evaluateFromStmtTSOrSysVariable(stmtAsOfTS)
return p.evaluateFromStmtTSOrSysVariable(stmtAsOfTS, evaluateTS)
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What's the difference between OnExecutePreparedStmt and OnSelectTable, why do we need to calculate the TS in two places? Is it possible to merge them into one?

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Here we set the ts evaluator which needs to be calculated to staleness processor when preparing, and it'll be returned and set to plan cache.

When invoking OnExecutePreparedStmt, it only uses the ts evaluator from plan cache, so it's not necessary to set a evaluator that requires calculation to get a timestamp.

cfzjywxk
cfzjywxk approved these changes Apr 20, 2023
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sessiontxn/staleread/processor.go
@@ -201,7 +204,7 @@ func (p *staleReadProcessor) OnExecutePreparedStmt(preparedTSEvaluator Staleness
return err
}
}
return p.evaluateFromStmtTSOrSysVariable(stmtTS)
return p.evaluateFromStmtTSOrSysVariable(stmtTS, nil)
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We could add some comments about the above logic.

@ti-chi-bot ti-chi-bot added the status/LGT1 Indicates that a PR has LGTM 1. label Apr 20, 2023
@ti-chi-bot ti-chi-bot added the needs-cherry-pick-release-7.1 Should cherry pick this PR to release-7.1 branch. label Apr 20, 2023
@you06
recalculate staleread ts when statement is cached
d19bd5a 
Signed-off-by: you06 <you1474600@gmail.com>

lint

Signed-off-by: you06 <you1474600@gmail.com>

add more test cases

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add comment

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add comment

Signed-off-by: you06 <you1474600@gmail.com>
@you06
stable resultset
12458ad 
Signed-off-by: you06 <you1474600@gmail.com>
@ti-chi-bot ti-chi-bot added status/LGT2 Indicates that a PR has LGTM 2. and removed status/LGT1 Indicates that a PR has LGTM 1. labels Apr 20, 2023
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qw4990 commented Apr 20, 2023

/merge

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This pull request has been accepted and is ready to merge.

Commit hash: 12458ad

@ti-chi-bot ti-chi-bot added the status/can-merge Indicates a PR has been approved by a committer. label Apr 20, 2023
@ti-chi-bot ti-chi-bot merged commit dc3f1e3 into pingcap:master Apr 20, 2023
@ti-chi-bot ti-chi-bot mentioned this pull request Apr 20, 2023
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In response to a cherrypick label: new pull request created to branch release-7.1: #43257.

ti-chi-bot bot pushed a commit that referenced this pull request Apr 25, 2023
@ti-chi-bot
planner: recalculate as-of ts of staleread when plan is cached (#43204)…
edd31b1 
… (#43257)

close #43044
@you06 you06 added affects-6.5 needs-cherry-pick-release-6.5 Should cherry pick this PR to release-6.5 branch. and removed affects-6.5 labels May 5, 2023
@ti-chi-bot ti-chi-bot mentioned this pull request May 5, 2023
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In response to a cherrypick label: new pull request created to branch release-6.5: #43550.

@you06 you06 mentioned this pull request May 5, 2023
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ti-chi-bot bot pushed a commit that referenced this pull request May 10, 2023
@ti-chi-bot
planner: recalculate as-of ts of staleread when plan is cached (#43204)…
52b57dd 
… (#43550)

close #43044
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@qw4990 qw4990 qw4990 approved these changes

@cfzjywxk cfzjywxk cfzjywxk approved these changes

@lcwangchao lcwangchao Awaiting requested review from lcwangchao

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prepare stmt with stale read get wrong result
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