Fix ALTER QUERY MODIFY SQL SECURITY

[pufit]

Changelog category (leave one):

• Bug Fix (user-visible misbehavior in an official stable release)

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

Fix the ALTER QUERY MODIFY SQL SECURITY queries to override the table's DDL correctly.

Closes #61245

Documentation entry for user-facing changes

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[robot-ch-test-poll3]

This is an automated comment for commit 1bafdf3 with description of existing statuses. It's updated for the latest CI running

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Check name	Description	Status
AST fuzzer	Runs randomly generated queries to catch program errors. The build type is optionally given in parenthesis. If it fails, ask a maintainer for help	❌ failure
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Performance Comparison	Measure changes in query performance. The performance test report is described in detail here. In square brackets are the optional part/total tests	❌ failure

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[vitlibar]

@pufit Could you explain please how ALTER MODIFY SQL SEQURITY is working now, before this your fix?

[vitlibar]

What will this line show if we run this test without this your fix?

[pufit]

0, because ALTER hadn't overridden the table's DDL properly. I missed it in the test because the table itself behaved correctly (see test on the line above), but all ALTER's changes were lost after restart.

[vitlibar]

Why do we need this hack here?

[pufit]

s_modify_definer moves the current position to

ALTER TABLE MODIFY DEFINER = pufit
                          /\                                     

but the ParserSQLSecurity takes AST DEFINER = ... [SQL SECURITY ...] or SQL SECURITY ... [DEFINER = ...]
So, in order to reuse this parser, we need to move the current position one step back.

ALTER TABLE MODIFY DEFINER = pufit
                 /\                                     

The crash in the linked issue happened because ASTSQLSecurity::formatImpl returns a canonical form DEFINER = ... SQL SECURITY DEFINER, so the ALTER query ALTER TABLE ... MODIFY SQL SECURITY DEFINER = pufit changes after format into ALTER TABLE ... MODIFY DEFINER = pufit SQL SECURITY DEFINER and can't be parsed again.

[vitlibar]

It's a bit too hacky, it seems better to modify ParserSQLSecurity and add there a parameter to its constructor which would allow to disable parsing either the DEFINER or SQL SECURITY keyword.

[vitlibar]

Please resolve the conflict.

[alexey-milovidov]

@pufit check this:

Stateless tests (release, analyzer, s3, DatabaseReplicated) [4/4] — fail: 1, passed: 1496, skipped: 27

[pufit]

@pufit check this:

Stateless tests (release, analyzer, s3, DatabaseReplicated) [4/4] — fail: 1, passed: 1496, skipped: 27

The problem with a replicated database is that we can't create users on all instances in our stateless tests.