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Bug #29053 SQL_CACHE in UNION causes non-deterministic functions to be cached

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Changed code to enforce that SQL_CACHE only in the first SELECT is used to turn on caching(as documented), but any SQL_NO_CACHE will turn off caching (not documented, but a useful behaviour, especially for machine generated queries). Added test cases to explicitly test the documented caching behaviour and test cases for the reported bug.
This commit is contained in:
dkatz@damien-katzs-computer.local 2007-06-18 17:16:20 -04:00
parent c67c49fff0
commit b89e4f9ef2
3 changed files with 92 additions and 3 deletions
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53
mysql-test/r/query_cache.result
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@ -179,12 +179,22 @@ a
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select * from t1 where a IN (select sql_cache a from t1);
a
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select * from t1 where a IN (select a from t1 union select sql_cache a from t1);
a
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show status like "Qcache_hits";
Variable_name Value
Qcache_hits 4
show status like "Qcache_queries_in_cache";
Variable_name Value
Qcache_queries_in_cache 2
Qcache_queries_in_cache 1
set query_cache_type=on;
reset query cache;
show status like "Qcache_queries_in_cache";
@ -195,6 +205,41 @@ a
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select * from t1 union select sql_no_cache * from t1;
a
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select * from t1 where a IN (select sql_no_cache a from t1);
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select * from t1 where a IN (select a from t1 union select sql_no_cache a from t1);
a
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select sql_cache sql_no_cache * from t1;
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select sql_cache * from t1 union select sql_no_cache * from t1;
a
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select sql_cache * from t1 where a IN (select sql_no_cache a from t1);
a
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select sql_cache * from t1 where a IN (select a from t1 union select sql_no_cache a from t1);
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show status like "Qcache_queries_in_cache";
Variable_name Value
Qcache_queries_in_cache 0
@ -1416,3 +1461,9 @@ insert into t1 values ('c');
a
drop table t1;
set GLOBAL query_cache_size= default;
set GLOBAL query_cache_size=1000000;
create table t1 (a char);
insert into t1 values ('c');
a
drop table t1;
set GLOBAL query_cache_size= default;

34
mysql-test/t/query_cache.test
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@ -89,7 +89,11 @@ show status like "Qcache_queries_in_cache";
select sql_cache * from t1 union select * from t1;
set query_cache_type=2;
select sql_cache * from t1 union select * from t1;
# all sql_cache statements, except for the first select, are ignored.
select * from t1 union select sql_cache * from t1;
select * from t1 where a IN (select sql_cache a from t1);
select * from t1 where a IN (select a from t1 union select sql_cache a from t1);
show status like "Qcache_hits";
show status like "Qcache_queries_in_cache";
set query_cache_type=on;
@ -102,6 +106,15 @@ show status like "Qcache_queries_in_cache";
# SELECT SQL_NO_CACHE
#
select sql_no_cache * from t1;
# sql_no_cache can occur in any nested select to turn on cacheing for the whole
# expression and it will always override a sql_cache statement.
select * from t1 union select sql_no_cache * from t1;
select * from t1 where a IN (select sql_no_cache a from t1);
select * from t1 where a IN (select a from t1 union select sql_no_cache a from t1);
select sql_cache sql_no_cache * from t1;
select sql_cache * from t1 union select sql_no_cache * from t1;
select sql_cache * from t1 where a IN (select sql_no_cache a from t1);
select sql_cache * from t1 where a IN (select a from t1 union select sql_no_cache a from t1);
show status like "Qcache_queries_in_cache";
drop table t1;
#
@ -994,4 +1007,25 @@ drop table t1;
set GLOBAL query_cache_size= default;
#
# Bug #29053 SQL_CACHE in UNION causes non-deterministic functions to be cached
#
set GLOBAL query_cache_size=1000000;
create table t1 (a char);
insert into t1 values ('c');
let $q1= `select RAND() from t1 union select sql_cache 1 from t1;`;
let $q2= `select RAND() from t1 union select sql_cache 1 from t1;`;
# disabling the logging of the query because the times are different each run.
--disable_query_log
eval select a from t1 where "$q1" = "$q2";
--enable_query_log
drop table t1;
set GLOBAL query_cache_size= default;
# End of 5.0 tests

8
sql/sql_yacc.yy
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@ -4363,8 +4363,12 @@ select_option:
}
| SQL_CACHE_SYM
{
/* Honor this flag only if SQL_NO_CACHE wasn't specified. */
if (Lex->select_lex.sql_cache != SELECT_LEX::SQL_NO_CACHE)
/*
Honor this flag only if SQL_NO_CACHE wasn't specified AND
we are parsing the outermost SELECT in the query.
*/
if (Lex->select_lex.sql_cache != SELECT_LEX::SQL_NO_CACHE &&
Lex->current_select == &Lex->select_lex)
{
Lex->safe_to_cache_query=1;
Lex->select_lex.options|= OPTION_TO_QUERY_CACHE;