br/lightning: change KvPair's row ID type from int64 to []bytes

[tangenta]

What problem does this PR solve?

Issue Number: ref #37119

Problem Summary:

In distributed execution framework, adding index job is split into multiple sub-tasks. Different TiDB instance may pick different sub-tasks up and execute them. Some of the sub-tasks may be rescheduled to another TiDB instance if the previous one halted due to some reasons.

In the perspective of the TiDB instance, it must be able to solve the reentrancy problem for the same range. Otherwise, an unexpected "duplicate key" error is reported even if there is no duplicate row actually.

To detect the duplicate key, lightning provides a field RowID(int64) to identify the row in the data source, appends it to the key slice and stores the key slice to the local engine. Before importing the data to TiKV, the iterator reads the keys, strips their row IDs, and compares the keys to decide whether they are duplicate.

Thus, it is the caller responsibility to guarantee that the same index key has the same RowID. For lightning, it is natural to use the "file offset" as the RowID. However, int64 is not enough to identify a row for adding index.

What is changed and how it works?

This PR changes the RowID type to []byte so that the handles(including int handles and common handles) can be used as the RowID.

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.

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• gozssky
• lance6716

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[lance6716]

rest lgtm

[tangenta]

/merge

[ti-chi-bot]

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

Commit hash: 9101b3a