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MDEV-24823 Crash with invalid multi-table update of view in 2nd execution of SP

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Before this patch mergeable derived tables / view used in a multi-table
update / delete were merged before the preparation stage.
When the merge of a derived table / view is performed the on expression
attached to it is fixed and ANDed with the where condition of the select S
containing this derived table / view. It happens after the specification of
the derived table / view has been merged into S. If the ON expression refers
to a non existing field an error is reported and some other mergeable derived
tables / views remain unmerged. It's not a problem if the multi-table
update / delete statement is standalone. Yet if it is used in a stored
procedure the select with incompletely merged derived tables / views may
cause a problem for the second call of the procedure. This does not happen
for select queries using derived tables / views, because in this case their
specifications are merged after the preparation stage at which all ON
expressions are fixed.
This patch makes sure that merging of the derived tables / views used in a
multi-table update / delete statement is performed after the preparation
stage.

Approved by Oleksandr Byelkin <sanja@mariadb.com>
This commit is contained in:
Igor Babaev
2021-04-19 19:52:06 -07:00
parent 5c5d24c772
commit b3b5d57e78
9 changed files with 171 additions and 26 deletions
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5
sql/sql_derived.cc
View File

@ -354,10 +354,6 @@ bool mysql_derived_merge(THD *thd, LEX *lex, TABLE_LIST *derived)
DBUG_RETURN(FALSE);
}
if (thd->lex->sql_command == SQLCOM_UPDATE_MULTI ||
thd->lex->sql_command == SQLCOM_DELETE_MULTI)
thd->save_prep_leaf_list= TRUE;
arena= thd->activate_stmt_arena_if_needed(&backup); // For easier test
if (!derived->merged_for_insert ||
@ -435,6 +431,7 @@ bool mysql_derived_merge(THD *thd, LEX *lex, TABLE_LIST *derived)
derived->on_expr= expr;
derived->prep_on_expr= expr->copy_andor_structure(thd);
}
thd->where= "on clause";
if (derived->on_expr &&
((!derived->on_expr->fixed &&
derived->on_expr->fix_fields(thd, &derived->on_expr)) ||