mariadb/mysql-test/t/status.test
unknown 310afbd4a9 Bug #30377: EXPLAIN loses last_query_cost when used with UNION
Currently the Last_query_cost session status variable shows
only the cost of a single flat subselect. For complex queries
(with subselects or unions etc) Last_query_cost is not valid
as it was showing the cost for the last optimized subselect.
Fixed by reseting to zero Last_query_cost when the complete
cost of the query cannot be determined.
Last_query_cost will be non-zero only for single flat queries.


mysql-test/r/status.result:
  Bug #30377: test case
mysql-test/t/status.test:
  Bug #30377: test case
sql/sql_lex.h:
  Bug #30377: helper function
sql/sql_select.cc:
  Bug #30377: don't assign cost if not on single level statement
2007-08-28 18:51:03 +03:00

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4.4 KiB
Text

# embedded server causes different stat
-- source include/not_embedded.inc
# PS causes different statistics
--disable_ps_protocol
connect (con1,localhost,root,,);
connect (con2,localhost,root,,);
flush status;
show status like 'Table_lock%';
connection con1;
SET SQL_LOG_BIN=0;
--disable_warnings
drop table if exists t1;
--enable_warnings
create table t1(n int) engine=myisam;
insert into t1 values(1);
connection con2;
lock tables t1 read;
unlock tables;
lock tables t1 read;
connection con1;
--send
update t1 set n = 3;
connection con2;
sleep 1;
unlock tables;
connection con1;
reap;
show status like 'Table_lock%';
drop table t1;
disconnect con2;
disconnect con1;
connection default;
# End of 4.1 tests
#
# last_query_cost
#
select 1;
show status like 'last_query_cost';
#
# Test for Bug #15933 max_used_connections is wrong after FLUSH STATUS
# if connections are cached
#
#
# The first suggested fix from the bug report was chosen
# (see http://bugs.mysql.com/bug.php?id=15933):
#
# a) On flushing the status, set max_used_connections to
# threads_connected, not to 0.
#
# b) Check if it is necessary to increment max_used_connections when
# taking a thread from the cache as well as when creating new threads
#
# Wait for at most $disconnect_timeout seconds for disconnects to finish.
let $disconnect_timeout = 10;
# Wait for any previous disconnects to finish.
FLUSH STATUS;
--disable_query_log
--disable_result_log
eval SET @wait_left = $disconnect_timeout;
let $max_used_connections = `SHOW STATUS LIKE 'max_used_connections'`;
eval SET @max_used_connections = SUBSTRING('$max_used_connections', 21)+0;
let $wait_more = `SELECT @max_used_connections != 1 && @wait_left > 0`;
while ($wait_more)
{
sleep 1;
FLUSH STATUS;
SET @wait_left = @wait_left - 1;
let $max_used_connections = `SHOW STATUS LIKE 'max_used_connections'`;
eval SET @max_used_connections = SUBSTRING('$max_used_connections', 21)+0;
let $wait_more = `SELECT @max_used_connections != 1 && @wait_left > 0`;
}
--enable_query_log
--enable_result_log
# Prerequisite.
SHOW STATUS LIKE 'max_used_connections';
# Save original setting.
SET @save_thread_cache_size=@@thread_cache_size;
SET GLOBAL thread_cache_size=3;
connect (con1,localhost,root,,);
connect (con2,localhost,root,,);
connection con1;
disconnect con2;
# Check that max_used_connections still reflects maximum value.
SHOW STATUS LIKE 'max_used_connections';
# Check that after flush max_used_connections equals to current number
# of connections. First wait for previous disconnect to finish.
FLUSH STATUS;
--disable_query_log
--disable_result_log
eval SET @wait_left = $disconnect_timeout;
let $max_used_connections = `SHOW STATUS LIKE 'max_used_connections'`;
eval SET @max_used_connections = SUBSTRING('$max_used_connections', 21)+0;
let $wait_more = `SELECT @max_used_connections != 2 && @wait_left > 0`;
while ($wait_more)
{
sleep 1;
FLUSH STATUS;
SET @wait_left = @wait_left - 1;
let $max_used_connections = `SHOW STATUS LIKE 'max_used_connections'`;
eval SET @max_used_connections = SUBSTRING('$max_used_connections', 21)+0;
let $wait_more = `SELECT @max_used_connections != 2 && @wait_left > 0`;
}
--enable_query_log
--enable_result_log
# Check that we don't count disconnected thread any longer.
SHOW STATUS LIKE 'max_used_connections';
# Check that max_used_connections is updated when cached thread is
# reused...
connect (con2,localhost,root,,);
SHOW STATUS LIKE 'max_used_connections';
# ...and when new thread is created.
connect (con3,localhost,root,,);
SHOW STATUS LIKE 'max_used_connections';
# Restore original setting.
connection default;
SET GLOBAL thread_cache_size=@save_thread_cache_size;
disconnect con3;
disconnect con2;
disconnect con1;
#
# Bug #30377: EXPLAIN loses last_query_cost when used with UNION
#
CREATE TABLE t1 ( a INT );
INSERT INTO t1 VALUES (1), (2);
SELECT a FROM t1 LIMIT 1;
SHOW SESSION STATUS LIKE 'Last_query_cost';
EXPLAIN SELECT a FROM t1;
SHOW SESSION STATUS LIKE 'Last_query_cost';
SELECT a FROM t1 UNION SELECT a FROM t1 ORDER BY a;
SHOW SESSION STATUS LIKE 'Last_query_cost';
EXPLAIN SELECT a FROM t1 UNION SELECT a FROM t1 ORDER BY a;
SHOW SESSION STATUS LIKE 'Last_query_cost';
SELECT a IN (SELECT a FROM t1) FROM t1 LIMIT 1;
SHOW SESSION STATUS LIKE 'Last_query_cost';
SELECT (SELECT a FROM t1 LIMIT 1) x FROM t1 LIMIT 1;
SHOW SESSION STATUS LIKE 'Last_query_cost';
SELECT * FROM t1 a, t1 b LIMIT 1;
SHOW SESSION STATUS LIKE 'Last_query_cost';
DROP TABLE t1;
# End of 5.0 tests