session: set tidb_opt_range_max_size to 0 when upgrading to v6.4.0+

[xuyifangreeneyes]

What problem does this PR solve?

Issue Number: ref #37176

Problem Summary:

What is changed and how it works?

v6.4.0 introduces tidb_opt_range_max_size to do memory control for building ranges. Its default value is 64MB. However, when a cluster upgrades from some version lower than v6.4.0 to v6.4.0+, we need to set tidb_opt_range_max_size to 0 for compatibility. In this way there is no memory control for building ranges, which is the old behavior before we introduce this variable.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
  Use v6.2.0 cluster, patch the pr's TiDB, select @@tidb_opt_range_max_size returns 0.
• 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:

• XuHuaiyu
• winoros

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[xuyifangreeneyes]

/merge

[ti-chi-bot]

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

Commit hash: 99694ad