*: stale reads compatible with prepare (#25156) by ti-srebot · Pull Request #25371 · pingcap/tidb

ti-srebot · 2021-06-11T11:33:06Z

cherry-pick #25156 to release-5.1
You can switch your code base to this Pull Request by using git-extras:

# In tidb repo:
git pr https://github.com/pingcap/tidb/pull/25371

After apply modifications, you can push your change to this PR via:

git push git@github.com:ti-srebot/tidb.git pr/25371:release-5.1-9189ec66ac47

What problem does this PR solve?

Issue Number: close #24932

Problem Summary: Prepare is now compatible with stale reads.

What is changed and how it works?

What's Changed:

snapshotTS != 0 is used to indicate that it is a stale read.

CachedPrepareStmt has a new field SnapshotTS to store the result of preprocessing in PrepareExec.
newExecutorBuilder has a new parameter, snapshotTS. It is passed from session.ExecutePreparedStmt, along cachedPlanExec or CompileExecutePreparedStmt. The one in session comes from CachedPrepareStmt.
Skip infoschema check in IsCachedExecOk and OptimizePreparedPlan, if snapshotTS != 0.
plannercore.Execute plan has a new field SnapshotTS to store the timestamp from CachedPrepareStmt.
executorExec.buildExecute will assign snapshotTS from plannercore.Execute plan to executorBuilder.

1-3 covered the prepared execution directly from session/mysql-protocol, and 4-5 covered the execution from plain SQL.

NEW CHANGES: to support dynamic timestamp like NOW() - INTERVAL 1 SECOND:

CachedPrepareStmt do not store infoschema anymore. You need to recheck infoschema before execute to ensure consistency anyway.
As Of statements evaluation is stored/prepared as a closure to support dynamic re-evaluation. For non-prepare statements, they can use LastSnapshotTS to avoid re-evaluation.

Check List

Tests

Unit test
Integration test
Manual test (add detailed scripts or steps below)

Release note

Support prepare stale reads SQL

Signed-off-by: ti-srebot <ti-srebot@pingcap.com>

ti-srebot · 2021-06-11T11:33:09Z

/run-all-tests

ti-srebot · 2021-06-11T11:33:14Z

@xhebox you're already a collaborator in bot's repo.

Signed-off-by: xhe <xw897002528@gmail.com>

xhebox · 2021-06-15T02:37:23Z

/run-all-tests

nolouch · 2021-06-15T02:51:13Z

/run-integration-common-test

nolouch

lgtm

ti-chi-bot · 2021-06-15T02:51:26Z

@nolouch: Thanks for your review. The bot only counts approvals from reviewers and higher roles in list, but you're still welcome to leave your comments.

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In response to this:

lgtm

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Yisaer · 2021-06-15T03:19:35Z

/merge

ti-chi-bot · 2021-06-15T03:19:37Z

@Yisaer: /merge in this pull request requires 2 approval(s).

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In response to this:

/merge

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nolouch · 2021-06-15T03:35:10Z

@Yisaer needs one more approval.

Yisaer

lgtm

ti-chi-bot · 2021-06-15T03:42:30Z

[REVIEW NOTIFICATION]

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Yisaer
nolouch

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Yisaer · 2021-06-15T03:42:36Z

/merge

ti-chi-bot · 2021-06-15T03:42:39Z

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

Details

Commit hash: e4770f2

xhebox · 2021-06-15T03:59:33Z

/run-check_dev

xhebox · 2021-06-15T04:11:14Z

/merge

ti-chi-bot · 2021-06-15T04:34:46Z

@ti-srebot: Your PR was out of date, I have automatically updated it for you.

At the same time I will also trigger all tests for you:

/run-all-tests

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

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nolouch · 2021-06-15T04:50:32Z

/run-check_dev

nolouch · 2021-06-15T05:17:24Z

/run-check_dev

cherry pick pingcap#25156 to release-5.1

567b378

Signed-off-by: ti-srebot <ti-srebot@pingcap.com>

ti-srebot requested review from a team as code owners June 11, 2021 11:33

ti-srebot requested review from XuHuaiyu and removed request for a team June 11, 2021 11:33

ti-chi-bot added the do-not-merge/cherry-pick-not-approved label Jun 11, 2021

ti-srebot mentioned this pull request Jun 11, 2021

*: stale reads compatible with prepare #25156

Merged

ti-srebot added sig/execution SIG execution sig/sql-infra SIG: SQL Infra size/XL Denotes a PR that changes 500-999 lines, ignoring generated files. type/5.1-cherry-pick labels Jun 11, 2021

ti-srebot assigned xhebox Jun 11, 2021

*: explicitstaleness is not cherry-picked yet

6444d33

Signed-off-by: xhe <xw897002528@gmail.com>

xhebox requested review from Yisaer and nolouch and removed request for a team and XuHuaiyu June 11, 2021 12:17

executor: fix fmt

e64cc7b

Signed-off-by: xhe <xw897002528@gmail.com>

zhouqiang-cl added the cherry-pick-approved Cherry pick PR approved by release team. label Jun 15, 2021

ti-chi-bot removed the do-not-merge/cherry-pick-not-approved label Jun 15, 2021

Merge branch 'release-5.1' into release-5.1-9189ec66ac47

e4770f2

nolouch approved these changes Jun 15, 2021

View reviewed changes

nolouch removed sig/execution SIG execution sig/sql-infra SIG: SQL Infra labels Jun 15, 2021

nolouch approved these changes Jun 15, 2021

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ti-chi-bot added the status/LGT1 Indicates that a PR has LGTM 1. label Jun 15, 2021

github-actions Bot added sig/execution SIG execution sig/sql-infra SIG: SQL Infra labels Jun 15, 2021

Yisaer approved these changes Jun 15, 2021

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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 Jun 15, 2021

ti-chi-bot added the status/can-merge Indicates a PR has been approved by a committer. label Jun 15, 2021

Merge branch 'release-5.1' into release-5.1-9189ec66ac47

fb6c0c8

ti-chi-bot added 2 commits June 15, 2021 12:12

Merge branch 'release-5.1' into release-5.1-9189ec66ac47

b33654e

Merge branch 'release-5.1' into release-5.1-9189ec66ac47

9796f3d

ti-chi-bot merged commit 270a4b2 into pingcap:release-5.1 Jun 15, 2021

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ti-srebot commented Jun 11, 2021 •

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