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Bug#28211 RENAME DATABASE and query cache don't play nicely together

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When all table blocks were removed from the query cache the client session
hung in a tight loop waiting on an impossible condition while consuming a lot
of CPU.

This patch also corrects an error which caused valid tables to sometimes be
removed from the query cache.


mysql-test/r/query_cache.result:
  Added test case to make sure server doesn't hang in a tight loop if last
  table block is removed from the cache.
mysql-test/t/query_cache.test:
  Added test case to make sure server doesn't hang in a tight loop if last
  table block is removed from the cache.
sql/sql_cache.cc:
  - Refactored loop over table blocks. The invalidate_table() function effects
    the elements over which we iterate. The previous stop condition was broken
    due to a compiler optimization error probably caused by the goto-statement
    pointing out of the loop. The effect being that tables_blocks was never
    checked for null values and thus the loop never terminated.
  - The new implementation uses two while loops instead of a goto-statement.
    The tables_blocks is a circular list which becomes null if the last table
    block is removed from the list.
This commit is contained in:
unknown
2007-06-18 17:46:29 +02:00
parent ad4da53510
commit b9dc6ad7ab
3 changed files with 145 additions and 27 deletions
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45
mysql-test/t/query_cache.test
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@ -1000,3 +1000,48 @@ set GLOBAL query_cache_min_res_unit=default;
set GLOBAL query_cache_size= default;
# End of 5.0 tests
#
# Bug #28211 RENAME DATABASE and query cache don't play nicely together
#
--disable_warnings
drop database if exists db1;
drop database if exists db2;
--enable_warnings
set GLOBAL query_cache_size=15*1024*1024;
create database db1;
use db1;
create table t1(c1 int)engine=myisam;
insert into t1(c1) values (1);
select * from db1.t1 f;
show status like 'Qcache_queries_in_cache';
rename schema db1 to db2;
show status like 'Qcache_queries_in_cache';
drop database db2;
set global query_cache_size=default;
--disable_warnings
drop database if exists db1;
drop database if exists db3;
--enable_wearnings
set GLOBAL query_cache_size=15*1024*1024;
create database db1;
create database db3;
use db1;
create table t1(c1 int) engine=myisam;
use db3;
create table t1(c1 int) engine=myisam;
use db1;
insert into t1(c1) values (1);
use mysql;
select * from db1.t1;
select c1+1 from db1.t1;
select * from db3.t1;
show status like 'Qcache_queries_in_cache';
rename schema db1 to db2;
show status like 'Qcache_queries_in_cache';
drop database db2;
drop database db3;
# End of 5.1 tests