fix the problem that offset in limit query for tiflash system tables doesn't take effect

[lidezhu]

What problem does this PR solve?

Issue Number: close #6747

Problem Summary: When query tiflash system tables from tidb, tidb will send query like select ... limit offset, 1024. And the query only stops when the num of return rows is less than length. However, the offset parameter is not repected by tiflash, and will always return the same result with any offset value. So if the system table has more than 1024 rows, the query will hang forever.

What is changed and how it works?

Port the implementation from https://github.com/ClickHouse/ClickHouse/blob/19.5/dbms/src/DataStreams/LimitBlockInputStream.cpp#L21

Check List

Tests

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

1. deploy a cluster and import data to make the tiflash system tables dt_segments with more than 1024 rows;
2. run the query select count(*) from information_schema.tiflash_segments and make sure it succeeds;

• 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

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• gengliqi
• windtalker

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[JaySon-Huang]

Does this bug also affect the v5.x versions or only the v6.x versions?

[windtalker]

LGTM

[gengliqi]

LGTM

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-5.2: #6759.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-5.3: #6760.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-5.4: #6761.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.1: #6762.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.5: #6763.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-5.0: #6764.

[lidezhu]

Does this bug also affect the v5.x versions or only the v6.x versions?

After verification, it just affect the master branch.

[JaySon-Huang]

Does this bug also affect the v5.x versions or only the v6.x versions?

After verification, it just affect the master branch.

OK, I think it is introduced by this PR: #6268