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mysql 5.6
Posted: Fri 08 Feb 2013 10:17
by andrea.m86
Hi
i've just installed mysql 5.6.
my applications, that use mydac 7.0, had a great slow-down!
others applications doesn't have any problems and mysql seems to work good.
Is there any compatibility problem with the latest mysql and your components?
Is there any upgrade that fix the issue?
Thanks
Andrea
Re: mysql 5.6
Posted: Mon 11 Feb 2013 16:41
by DemetrionQ
Hello.
Please, try downloading the latest MyDAC build (7.6.11) and check if this problem still exists.
Re: mysql 5.6
Posted: Tue 12 Feb 2013 13:12
by andrea.m86
Hi,
I've just upgraded to the latest version.
The problem remain!
I'm trying to connecting in direct mode but the situation is the same if i use libmysql.dll (upgraded to the latest 5.6)
please let me know what can i do.
Re: mysql 5.6
Posted: Wed 13 Feb 2013 11:09
by andrea.m86
i've noticed that a big part of the slowdown is due to the property defaultvalue of the queries.
If it is setted to true each query takes much more time to open.
but i need this property active...
Re: mysql 5.6
Posted: Fri 15 Feb 2013 18:01
by DemetrionQ
Hello.
To retrieve values of default fields, the following service query is executed when opening the table:
Code: Select all
SELECT cast('' AS CHAR(1)) TABLE_CATALOG
, TABLE_SCHEMA
, TABLE_NAME
, COLUMN_NAME
, ORDINAL_POSITION POSITION
, DATA_TYPE
, CHARACTER_MAXIMUM_LENGTH DATA_LENGTH
, NUMERIC_PRECISION DATA_PRECISION
, NUMERIC_SCALE DATA_SCALE
, (
CASE IS_NULLABLE
WHEN 'YES' THEN
1
ELSE
0
END) NULLABLE
, COLUMN_DEFAULT DEFAULT_VALUE
FROM
information_schema.COLUMNS
WHERE
TABLE_SCHEMA = 'test' /*Your Database Name*/
AND TABLE_NAME = 'table1' /*Your Table Name*/
ORDER BY
TABLE_SCHEMA
, TABLE_NAME
, ORDINAL_POSITION
Please execute this query singly (e.g., using the TMyQuery component) - and check the speed of the execution.
Re: mysql 5.6
Posted: Mon 18 Feb 2013 12:02
by andrea.m86
this query is much slower on mysql 5.6.
0,016 sec on Mysql 5.5
0.670 sec on Mysql 5.6
(I use a MyIsam as storage engine)
If you use the "explain" statement the results are different from a version to another:
Mysql 5.5:
key: TABLE_SCHEMA,TABLE_NAME
Using where; Open_frm_only; Scanned 0 databases; Using filesort
Mysql 5.6:
key: null
Using where; Open_frm_only; Scanned all databases; Using filesort
Re: mysql 5.6
Posted: Wed 20 Feb 2013 15:50
by DemetrionQ
Hello.
Unfortunately, we cannot affect this SQL query execution speed. Try testing the performance for a server based on the InnoDB engine.
Re: mysql 5.6
Posted: Mon 25 Feb 2013 15:03
by andrea.m86
no performance difference with innodb.
The performance become again good if you remove "ORDINAL_POSITION" from the order-by clause.
Also the result of the explain statement returns to be consistent with mysql 5.5
Re: mysql 5.6
Posted: Wed 27 Feb 2013 15:50
by DemetrionQ
Hello.
Thank you for information. We will investigate the possibility of changing this functionality in one of the next versions of MyDAC.
Re: mysql 5.6
Posted: Mon 04 Mar 2013 09:48
by andrea.m86
I reported the problem to oracle.
They opened a bug track. (bug 16423536)
Thanks for the help.