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MDEV-24346 valgrind error in main.precedence

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in queries like

  create view v1 as select 2 like 1 escape (3 in (select 0 union select 1));
  select 2 union select * from v1;

Item_func_like::escape was left uninitialized, because
Item_in_optimizer is const_during_execution()
but not actually const_item() during execution.

It's not, because const subquery evaluation was disabled for derived.
Practically it only needs to be disabled for multi-update
that runs fix_fields() before all tables are locked.
This commit is contained in:
Sergei Golubchik
2020-12-14 18:25:08 +01:00
parent 5785de72ac
commit a587ded283
5 changed files with 14 additions and 3 deletions
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7
sql/sql_update.cc
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@@ -1534,7 +1534,11 @@ int mysql_multi_update_prepare(THD *thd)
During prepare phase acquire only S metadata locks instead of SW locks to
keep prepare of multi-UPDATE compatible with concurrent LOCK TABLES WRITE
and global read lock.
Don't evaluate any subqueries even if constant, because
tables aren't locked yet.
*/
lex->context_analysis_only|= CONTEXT_ANALYSIS_ONLY_DERIVED;
if (thd->lex->sql_command == SQLCOM_UPDATE_MULTI)
{
if (open_tables(thd, &table_list, &table_count,
@@ -1557,6 +1561,9 @@ int mysql_multi_update_prepare(THD *thd)
{
DBUG_RETURN(TRUE);
}
lex->context_analysis_only&= ~CONTEXT_ANALYSIS_ONLY_DERIVED;
(void) read_statistics_for_tables_if_needed(thd, table_list);
/* @todo: downgrade the metadata locks here. */