MDEV-27027 Atomic DDL: Assertion failed upon unsuccessful multi-RENAM… #4499
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…E TABLE
When executing an atomic sequence of RENAME operations, such as:
RENAME TABLE t1 TO t2, t3 TO t4, ...
any failure in the sequence triggers a rollback of previously completed
renames to preserve atomicity.
However, when an error occurs, `my_error()` is invoked immediately, which
sets the `thd->is_error()` flag. This premature flag setting causes
the rollback logic to misinterpret the thread state, leading to incorrect
reversion behavior and assertion failures.
To address this, the errors are now not emitted immediately but captured
and postponed. A new class `Postponed_error_handler` is introduced for
this purpose. Only after all operations are completed (including
possible DDL reversion), the captured errors are emitted.
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…E TABLE
Description
When executing an atomic sequence of RENAME operations, such as:
RENAME TABLE t1 TO t2, t3 TO t4, ...
any failure in the sequence triggers a rollback of previously completed renames to preserve atomicity.
However, when an error occurs,
my_error()is invoked immediately, which sets thethd->is_error()flag. This premature flag setting causes the rollback logic to misinterpret the thread state, leading to incorrect reversion behavior and assertion failures.To address this, the errors are now not emitted immediately but captured and postponed. A new class
Postponed_error_handleris introduced for this purpose. Only after all operations are completed (including possible DDL reversion), the captured errors and warnings are emitted.Release Notes
Unsuccessful multi-table RENAME operations might lead to undefined behavior or a crash instead of proper DDL reversion and printing the error message.
How can this PR be tested?
/mtr main.renameIf the changes are not amenable to automated testing, please explain why not and carefully describe how to test manually.
Basing the PR against the correct MariaDB version
mainbranch.PR quality check