feat: authoritative query timeout for vttablet from vtgate

[harshit-gangal]

Description

This PR uses the comment directive QUERY_TIMEOUT_MS, session variable query_timeout and VTGate's flag query-timeout to set the query timeout on the execute options sent to vttablet.

VTTablet will consider this as authoritative over VTTablet's default query timeout.
VTGate will set the execution context using the same timeout value.

QUERY_TIMEOUT_MS will override the session value if set. If nothing is set then no timeout value will be sent down to VTTablet.

Order of precedence: Query Comment > Session Value > VTGate flag.

If the query is executed inside a transaction then only the smaller value of query vs transaction timeout will be considered at VTTablet.

Related Issue(s)

• Closes Feature Request: allow DDL statements to run for unlimited time #16710
• Bug Report: Query timeout applies only on Route and not on the entire query execution #16624
• VTgate --query-timeout is ignored  #13694

Checklist

• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

[vitess-bot]

Review Checklist

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[codecov]

Codecov Report

Attention: Patch coverage is 90.35088% with 11 lines in your changes missing coverage. Please review.

Project coverage is 68.93%. Comparing base (e0a5069) to head (a857a5e).
Report is 58 commits behind head on main.

Files with missing lines	Patch %	Lines
go/vt/vtgate/engine/dbddl.go	60.00%	4 Missing ⚠️
go/vt/vtgate/engine/insert_select.go	25.00%	3 Missing ⚠️
go/vt/vttablet/tabletserver/tabletserver.go	90.00%	2 Missing ⚠️
go/vt/sqlparser/comments.go	97.77%	1 Missing ⚠️
go/vt/vtgate/planbuilder/builder.go	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16735      +/-   ##
==========================================
- Coverage   68.94%   68.93%   -0.02%     
==========================================
  Files        1565     1565              
  Lines      201748   201764      +16     
==========================================
- Hits       139093   139083      -10     
- Misses      62655    62681      +26     

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[shlomi-noach]

Noting for self reference this usage sample:

select /*vt+ QUERY_TIMEOUT_MS=0 */ sleep(5) from dual

Still unsure about the relevance of the foreign key related changes.

[harshit-gangal]

Still unsure about the relevance of the foeign key related changes.

@shlomi-noach
Those are Query Hint related changes, brought all the extraction of query hints into a single struct.

[shlomi-noach]

Suggested change

	`query_timeout` session system variable, or `query-timeout` flag is set.
	`query_timeout` session system variable, or `query-timeout` flag are set.

[harshit-gangal]

even one of them set is enough.

[harshit-gangal]

I think is is more apt here.

[vitess-bot]

Hello! 👋

This Pull Request is now handled by arewefastyet. The current HEAD and future commits will be benchmarked.

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