Commit b89e4f9e authored by dkatz@damien-katzs-computer.local's avatar dkatz@damien-katzs-computer.local
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Bug #29053 SQL_CACHE in UNION causes non-deterministic functions to be cached 

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.
parent c67c49ff

mysql-test/r/query_cache.result

+52 −1
Original line number Diff line number Diff line
@@ -179,12 +179,22 @@ a 
1

2

3

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

1

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3

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 
1

2

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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);

a

1

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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;

a

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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

1

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select sql_cache * from t1 where a IN (select a from t1 union select sql_no_cache a from t1);

a

1

2

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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;

mysql-test/t/query_cache.test

+34 −0
Original line number Diff line number Diff line
@@ -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

sql/sql_yacc.yy

+6 −2
Original line number Diff line number Diff line
@@ -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;