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Bug#19111: TRIGGERs selecting from a VIEW on the firing base table fail.

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In a trigger or a function used in a statement it is possible to do
SELECT from a table being modified by the statement.  However,
encapsulation of such SELECT into a view and selecting from a view
instead of direct SELECT was not possible.

This happened because tables used by views (which in their turn
were used from functions/triggers) were not excluded from checks
in unique_table() routine as it happens for the rest of tables
added to the statement table list for prelocking.

With this fix we ignore all such tables in unique_table(), thus
providing consistency: inside a trigger or a functions SELECT from
a view may be used where plain SELECT is allowed.  Modification of
the same table from function or trigger is still disallowed.  Also,
this patch doesn't affect the case where SELECT from the table being
modified is done outside of function of trigger, such SELECTs are
still disallowed (this limitation and visibility problem when function
select from a table being modified are subjects of bug 21326).  See
also bug 22427.
This commit is contained in:
kroki/tomash@moonlight.intranet
2006-10-10 13:44:04 +04:00
parent 6d05e32d82
commit 4a28f8f1a0
3 changed files with 62 additions and 5 deletions
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11
sql/sql_base.cc
View File

@ -805,6 +805,10 @@ TABLE_LIST *find_table_in_list(TABLE_LIST *table,
Also SELECT::exclude_from_table_unique_test used to exclude from check
tables of main SELECT of multi-delete and multi-update
We also skip tables with TABLE_LIST::prelocking_placeholder set,
because we want to allow SELECTs from them, and their modification
will rise the error anyway.
TODO: when we will have table/view change detection we can do this check
only once for PS/SP
@ -851,12 +855,13 @@ TABLE_LIST* unique_table(THD *thd, TABLE_LIST *table, TABLE_LIST *table_list)
if (((! (res= find_table_in_global_list(table_list, d_name, t_name))) &&
(! (res= mysql_lock_have_duplicate(thd, table, table_list)))) ||
((!res->table || res->table != table->table) &&
res->select_lex && !res->select_lex->exclude_from_table_unique_test))
res->select_lex && !res->select_lex->exclude_from_table_unique_test &&
!res->prelocking_placeholder))
break;
/*
If we found entry of this table or or table of SELECT which already
If we found entry of this table or table of SELECT which already
processed in derived table or top select of multi-update/multi-delete
(exclude_from_table_unique_test).
(exclude_from_table_unique_test) or prelocking placeholder.
*/
table_list= res->next_global;
DBUG_PRINT("info",