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storage: calculate last_change_ts in rollback #13749

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merged 2 commits into from Nov 10, 2022
Merged

storage: calculate last_change_ts in rollback #13749

merged 2 commits into from Nov 10, 2022

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sticnarf
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@sticnarf sticnarf commented Nov 8, 2022

What is changed and how it works?

Issue Number: Ref #13694

What's Changed:

This commit supports calculating last_change_ts when writing a new
Rollback record.

To get the correct last_change_ts, we always call seek_write to find the
last write record before start_ts.

Check List

Tests

  • Unit test

Release note 

None

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ti-chi-bot commented Nov 8, 2022 •
edited

[REVIEW NOTIFICATION]

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  • ekexium

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@sticnarf
storage: calculate last_change_ts in rollback
75e6b63 
Signed-off-by: Yilin Chen <sticnarf@gmail.com>
@sticnarf sticnarf mentioned this pull request Nov 9, 2022
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@ti-chi-bot ti-chi-bot added the status/LGT1 Status: PR - There is already 1 approval label Nov 9, 2022
TonsnakeLin
TonsnakeLin reviewed Nov 10, 2022
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src/storage/txn/commands/check_secondary_locks.rs
assert_eq!(rollback.last_change_ts, 50.into());
assert_eq!(rollback.versions_to_last_change, 3);

// last_change_ts should point to the latest record before start_ts; prev
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Suggested change
// last_change_ts should point to the latest record before start_ts; prev
// last_change_ts should point to the latest record before start_ts; prev writes:

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Sorry, it's a compulsory new line limited by the line length.

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PTAL @ekexium

@ti-chi-bot ti-chi-bot added status/LGT2 Status: PR - There are already 2 approvals and removed status/LGT1 Status: PR - There is already 1 approval labels Nov 10, 2022
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/merge

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@sticnarf: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

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

Commit hash: 75e6b63

@ti-chi-bot ti-chi-bot added the status/can-merge Status: Can merge to base branch label Nov 10, 2022
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@sticnarf: 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.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

@ti-chi-bot ti-chi-bot merged commit 0339d51 into tikv:master Nov 10, 2022
@ti-chi-bot ti-chi-bot added this to the Pool milestone Nov 10, 2022
ti-chi-bot added a commit that referenced this pull request Nov 23, 2022
@sticnarf @ti-chi-bot
txn: revert "calculate last_change_ts in rollback" (#13834)
8ce818b 
ref #13694, ref #13749

This commit reverts #13749 (calculate last_change_ts in rollback).

If we calculate last_change_ts, consider the following case:
Key k has a write record with commit_ts = 5.
1. Prewrite k, start_ts = 10
2. Rollback k, start_ts = 30, last_commit_ts = 5.
3. Commit k, start_ts = 10, commit_ts = 20

Then, read with ts = 40, it will get an incorrect last_commit_ts from
the rollback record.

There is no easy way to handle the rollback case. I choose to give up
calculating it.

Signed-off-by: Yilin Chen <sticnarf@gmail.com>

Co-authored-by: Ti Chi Robot <ti-community-prow-bot@tidb.io>
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@MyonKeminta MyonKeminta MyonKeminta approved these changes

@ekexium ekexium ekexium approved these changes

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