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MDEV-32583 UUID() should be treated as stochastic for the purposes of forcing query materialization

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RAND() and UUID() are treated differently with respect to subquery
materialization both should be marked as uncacheable, forcing materialization.
Altered Create_func_uuid(_short)::create_builder().
Added comment in header about UNCACHEABLE_RAND meaning also unmergeable.
This commit is contained in:
Rex
2024-03-19 08:50:19 +12:00
parent 5979dcf95b
commit 9e800eda86
5 changed files with 43 additions and 3 deletions
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13
mysql-test/main/func_misc.result
View File

@ -1732,3 +1732,16 @@ RELEASE_ALL_LOCKS()
SELECT LOCK_MODE, LOCK_TYPE, TABLE_SCHEMA
FROM information_schema.metadata_lock_info WHERE thread_id>0 ORDER BY TABLE_SCHEMA;
LOCK_MODE LOCK_TYPE TABLE_SCHEMA
#
# MDEV-32583 UUID() should be treated as stochastic for the purposes of
# forcing query materialization
#
create table t1 as WITH cte AS (SELECT UUID() as r FROM seq_1_to_10)
SELECT r as r1, r FROM cte;
select count(*) from t1 where r1!=r;
count(*)
0
drop table t1;
#
# End of 10.5 tests
#

15
mysql-test/main/func_misc.test
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@ -1361,3 +1361,18 @@ FROM information_schema.metadata_lock_info WHERE thread_id>0 ORDER BY TABLE_SCHE
--enable_ps2_protocol
--enable_view_protocol
--echo #
--echo # MDEV-32583 UUID() should be treated as stochastic for the purposes of
--echo # forcing query materialization
--echo #
--source include/have_sequence.inc
create table t1 as WITH cte AS (SELECT UUID() as r FROM seq_1_to_10)
SELECT r as r1, r FROM cte;
select count(*) from t1 where r1!=r;
drop table t1;
--echo #
--echo # End of 10.5 tests
--echo #

4
sql/item_create.cc
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@ -5301,7 +5301,7 @@ Create_func_uuid::create_builder(THD *thd)
{
DBUG_ENTER("Create_func_uuid::create");
thd->lex->set_stmt_unsafe(LEX::BINLOG_STMT_UNSAFE_SYSTEM_FUNCTION);
thd->lex->safe_to_cache_query= 0;
thd->lex->uncacheable(UNCACHEABLE_RAND); // disallow cache and query merges
DBUG_RETURN(new (thd->mem_root) Item_func_uuid(thd));
}
@ -5313,7 +5313,7 @@ Create_func_uuid_short::create_builder(THD *thd)
{
DBUG_ENTER("Create_func_uuid_short::create");
thd->lex->set_stmt_unsafe(LEX::BINLOG_STMT_UNSAFE_SYSTEM_FUNCTION);
thd->lex->safe_to_cache_query= 0;
thd->lex->uncacheable(UNCACHEABLE_RAND); // disallow cache and query merges
DBUG_RETURN(new (thd->mem_root) Item_func_uuid_short(thd));
}

9
sql/sql_lex.h
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@ -3621,6 +3621,15 @@ public:
return (context_analysis_only & CONTEXT_ANALYSIS_ONLY_VIEW);
}
/**
Mark all queries in this lex structure as uncacheable for the cause given
@param cause the reason queries are to be marked as uncacheable
Note, any cause is sufficient for st_select_lex_unit::can_be_merged() to
disallow query merges.
*/
inline void uncacheable(uint8 cause)
{
safe_to_cache_query= 0;

5
sql/sql_priv.h
View File

@ -316,7 +316,10 @@
*/
/* This subquery has fields from outer query (put by user) */
#define UNCACHEABLE_DEPENDENT_GENERATED 1
/* This subquery contains functions with random result */
/*
This subquery contains functions with random result.
Something that is uncacheable is by default unmergeable.
*/
#define UNCACHEABLE_RAND 2
/* This subquery contains functions with side effect */
#define UNCACHEABLE_SIDEEFFECT 4