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A fix and a test case for Bug#26141 mixing table types in trigger

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causes full table lock on innodb table.
Also fixes Bug#28502 Triggers that update another innodb table 
will block on X lock unnecessarily (duplciate).
Code review fixes.

Both bugs' synopses are misleading: InnoDB table is
not X locked. The statements, however, cannot proceed concurrently, 
but this happens due to lock conflicts for tables used in triggers,
not for the InnoDB table. 

If a user had an InnoDB table, and two triggers, AFTER UPDATE and 
AFTER INSERT, competing for different resources (e.g. two distinct
MyISAM tables), then these two triggers would not be able to execute
concurrently. Moreover, INSERTS/UPDATES of the InnoDB table would
not be able to run concurrently. 
The problem had other side-effects (see respective bug reports).

This behavior was a consequence of a shortcoming of the pre-locking
algorithm, which would not distinguish between different DML operations
(e.g. INSERT and DELETE) and pre-lock all the tables
that are used by any trigger defined on the subject table.

The idea of the fix is to extend the pre-locking algorithm to keep track,
for each table, what DML operation it is used for and not
load triggers that are known to never be fired.
This commit is contained in:
kostja@bodhi.(none)
2007-07-12 22:26:41 +04:00
parent 392b283f3d
commit 5ab4b6f1ac
18 changed files with 1255 additions and 58 deletions
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28
sql/sql_trigger.cc
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@@ -942,17 +942,6 @@ bool Table_triggers_list::check_n_load(THD *thd, const char *db,
table->triggers= triggers;
/*
Construct key that will represent triggers for this table in the set
of routines used by statement.
*/
triggers->sroutines_key.length= 1+strlen(db)+1+strlen(table_name)+1;
if (!(triggers->sroutines_key.str=
alloc_root(&table->mem_root, triggers->sroutines_key.length)))
DBUG_RETURN(1);
triggers->sroutines_key.str[0]= TYPE_ENUM_TRIGGER;
strxmov(triggers->sroutines_key.str+1, db, ".", table_name, NullS);
/*
TODO: This could be avoided if there is no triggers
for UPDATE and DELETE.
@@ -991,6 +980,15 @@ bool Table_triggers_list::check_n_load(THD *thd, const char *db,
DBUG_ASSERT(lex.sphead == 0);
goto err_with_lex_cleanup;
}
/*
Not strictly necessary to invoke this method here, since we know
that we've parsed CREATE TRIGGER and not an
UPDATE/DELETE/INSERT/REPLACE/LOAD/CREATE TABLE, but we try to
maintain the invariant that this method is called for each
distinct statement, in case its logic is extended with other
types of analyses in future.
*/
lex.set_trg_event_type_for_tables();
lex.sphead->set_info(0, 0, &lex.sp_chistics, (ulong) *trg_sql_mode);
@@ -1550,6 +1548,12 @@ bool Table_triggers_list::process_triggers(THD *thd, trg_event_type event,
new_field= record1_field;
old_field= trigger_table->field;
}
/*
This trigger must have been processed by the pre-locking
algorithm.
*/
DBUG_ASSERT(trigger_table->pos_in_table_list->trg_event_map &
static_cast<uint>(1 << static_cast<int>(event)));
thd->reset_sub_statement_state(&statement_state, SUB_STMT_TRIGGER);
err_status= sp_trigger->execute_trigger
@@ -1568,7 +1572,7 @@ bool Table_triggers_list::process_triggers(THD *thd, trg_event_type event,
SYNOPSIS
mark_fields_used()
thd Current thread context
event Type of event triggers for which we are going to inspect
event Type of event triggers for which we are going to ins
DESCRIPTION
This method marks fields of subject table which are read/set in its