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MDEV-35813 Unnecessary InnoDB log writes in INSERT…SELECT

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ha_innobase::extra(): Conditionally avoid a log write that had been
added in commit e5b9dc15368c7597a70569048eebfc5e05e98ef4 (MDEV-25910)
because it may be invoked as part of select_insert::prepare_eof()
and not only during DDL operations.

Reviewed by: Sergei Golubchik
This commit is contained in:
Marko Mäkelä 2025-03-14 13:06:37 +02:00 committed by Sergei Golubchik
parent 04e114aec0
commit c3c5cd9377
2 changed files with 14 additions and 1 deletions
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2
sql/sql_table.cc
View File

@ -11135,7 +11135,7 @@ do_continue:;
debug_crash_here("ddl_log_alter_after_copy"); // Use old table
/*
We are new ready to use the new table. Update the state in the
We are now ready to use the new table. Update the state in the
ddl log so that we recovery know that the new table is ready and
in case of crash it should use the new one and log the query
to the binary log.

13
storage/innobase/handler/ha_innodb.cc
View File

@ -15958,9 +15958,22 @@ ha_innobase::extra(
break;
case HA_EXTRA_END_ALTER_COPY:
trx = check_trx_exists(ha_thd());
if (!m_prebuilt->table->skip_alter_undo) {
/* This could be invoked inside INSERT...SELECT.
We do not want any extra log writes, because
they could cause a severe performance regression. */
break;
}
m_prebuilt->table->skip_alter_undo = 0;
if (!m_prebuilt->table->is_temporary()
&& !high_level_read_only) {
/* The extra log write is necessary for
ALTER TABLE...ALGORITHM=COPY, because
a normal transaction commit would be a no-op
because no undo log records were generated.
This log write will also be unnecessarily executed
during CREATE...SELECT, which is the other caller of
handler::extra(HA_EXTRA_BEGIN_ALTER_COPY). */
log_buffer_flush_to_disk();
}
break;