database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-07-30 16:24:05 +03:00
Code Activity

MDEV-17595 - ALTER TABLE ADD FOREIGN KEY crash

Browse Source 
ALTER TABLE ... ADD FOREIGN KEY may trigger assertion failure when
it has LOCK=EXCLUSIVE clause or concurrent FLUSH TABLES is being
executed.

In both cases being altered table is marked as flushed, which forces
subsequent attempt to open parent table to re-open. Which in turn is
not allowed while transaction is running.

Rather than opening parent table, just take appropriate MDL lock.

Also removed table_already_fk_prelocked() check: MDL itself has much
better methods to handle duplicate locks. E.g. the former won't acquire
MDL_SHARED_NO_WRITE if it already has MDL_SHARED_READ.
This commit is contained in:
Sergey Vojtovich
2019-03-07 13:43:53 +04:00
parent 0a0eed8016
commit 149b754768
3 changed files with 36 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files

20
sql/sql_table.cc
View File

@ -9074,6 +9074,8 @@ bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
new_table->file->get_foreign_key_list(thd, &fk_list);
while ((fk= fk_list_it++))
{
MDL_request mdl_request;
if (lower_case_table_names)
{
char buf[NAME_LEN];
@ -9085,20 +9087,14 @@ bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
len = my_casedn_str(files_charset_info, buf);
thd->make_lex_string(fk->referenced_table, buf, len);
}
if (table_already_fk_prelocked(table_list, fk->referenced_db,
fk->referenced_table, TL_READ_NO_INSERT))
continue;
TABLE_LIST *tl= (TABLE_LIST *) thd->alloc(sizeof(TABLE_LIST));
tl->init_one_table_for_prelocking(fk->referenced_db->str, fk->referenced_db->length,
fk->referenced_table->str, fk->referenced_table->length,
NULL, TL_READ_NO_INSERT, false, NULL, 0,
&thd->lex->query_tables_last);
mdl_request.init(MDL_key::TABLE,
fk->referenced_db->str, fk->referenced_table->str,
MDL_SHARED_NO_WRITE, MDL_TRANSACTION);
if (thd->mdl_context.acquire_lock(&mdl_request,
thd->variables.lock_wait_timeout))
goto err_new_table_cleanup;
}
if (open_tables(thd, &table_list->next_global, &tables_opened, 0,
&alter_prelocking_strategy))
goto err_new_table_cleanup;
}
}
/*