pkg/ddl, pkg/sessionctx: pass fulltext sysvars to TiCI | tidb-test=a9bf2dca824dc746361234cd4d763178e0eedd13 tiflash=feature-fts

[wjhuang2016]

What problem does this PR solve?

Issue Number: ref #63937

Problem Summary:

• Support FULLTEXT INDEX creation system variables: innodb_ft_max_token_size, innodb_ft_min_token_size, ngram_token_size, innodb_ft_enable_stopword, innodb_ft_server_stopword_table, innodb_ft_user_stopword_table.
• Read stopwords from the configured stopword table and pass them to TiCI at index creation time (including CREATE TABLE ... FULLTEXT INDEX ...).

What changed and how does it work?

• Add the above sysvars with validation and cluster persistence.
• Capture sysvar values into the relevant DDL jobs (ADD FULLTEXT INDEX and CREATE TABLE with FULLTEXT indexes), so each new FULLTEXT index creation uses a stable snapshot of the sysvars (existing indexes are not affected).
• Extend TiDB internal TiCI proto (pkg/tici/tici.proto) to carry CreateIndexRequest.parser_info and ParserInfo.stop_words.
• During FULLTEXT index creation, TiDB builds parser_info.parser_params from job sysvars and (for standard parser + stopwords enabled + stopword table configured) reads stopwords from the table (single VARCHAR column value) and sends the de-duplicated list via parser_info.stop_words.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No need to test

  • I checked and no code files have been changed.

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

[codecov]

Codecov Report

❌ Patch coverage is 49.57447% with 237 lines in your changes missing coverage. Please review.
✅ Project coverage is 72.4720%. Comparing base (2d2bd57) to head (66554a9).
⚠️ Report is 52 commits behind head on feature/fts.

Additional details and impacted files

@@                 Coverage Diff                 @@
##           feature/fts     #65967        +/-   ##
===================================================
+ Coverage      72.3094%   72.4720%   +0.1626%     
===================================================
  Files             1895       1922        +27     
  Lines           533272     535482      +2210     
===================================================
+ Hits            385606     388075      +2469     
+ Misses          123717     123272       -445     
- Partials         23949      24135       +186     

Flag	Coverage Δ
integration	46.2513% <2.3404%> (-0.0280%)	⬇️
unit	70.0566% <49.5744%> (+0.1726%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	52.8700% <ø> (ø)
parser	∅ <ø> (∅)
br	63.2627% <ø> (+0.2240%)	⬆️

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[wjhuang2016]

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[wjhuang2016]

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[wjhuang2016]

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[wjhuang2016]

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[wjhuang2016]

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[OliverS929]

If we are to use the original parser type from the old full-text index, addtional checks and changes might be needed to check the parser type itself, as the old full-text has a wilder scope of support compared to the one we are implementing at the moment.

[wjhuang2016]

Thanks for the heads-up. I did not change the parser-type compatibility logic in this PR; will follow up separately if/when we need to support carrying over legacy FULLTEXT parser settings.

[wjhuang2016]

/retest

[ti-chi-bot]

@JinheLin: adding LGTM is restricted to approvers and reviewers in OWNERS files.

Details

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: JinheLin, OliverS929, winoros
Once this PR has been reviewed and has the lgtm label, please assign benjamin2037, yudongusa for approval. For more information see the Code Review Process.
Please ensure that each of them provides their approval before proceeding.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• OWNERS [OliverS929,winoros]
• pkg/ddl/OWNERS
• pkg/sessionctx/vardef/OWNERS
• pkg/sessionctx/variable/OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2026-02-05 09:12:23.392361783 +0000 UTC m=+344614.493760496: ☑️ agreed by OliverS929.
• 2026-02-06 12:04:01.834087979 +0000 UTC m=+9485.801264843: ☑️ agreed by winoros.

[wjhuang2016]

/retest

[wjhuang2016]

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[JaySon-Huang]

/retest