… DNS lookups per authentication attempt, you just need to set skip_name_resolve in your my.cnf file and restart MySQL. But before you do that, run the following command: mysql> SELECT user, host FROM mysql.user -> WHERE host… information on how and why MySQL does both a forward and reverse DNS lookup on authentication attempts by default, read the MySQL manual page.
Comment: Is DNS the Achilles heel in your MySQL installation?
May 31, 2008 By 16 Comments
… magnifies because of various bugs with host-cache in different MySQL versions which could cause more resolves when needed as well… – I’ve seen some operating systems building MySQL with tcp wrappers – in this case reverse lookup happens even if you have –skip-name…
Post: To pack or not to pack - MyISAM Key compression
May 13, 2006 By 4 Comments
… blocks need to be treated differently. For uncompressed index blocks MySQL can do binary search inside the page – kind of jumping… DEFAULT configuration lookups for integer keys are fast and forward scans are. It is however slow to do reverse scan on the… a bit of uncompression than to traverse large memory areas. Reverse index scan performance got some 8 times faster and join…
Comment: Full text search for all MySQL Storage Engines
June 28, 2006 By 37 Comments
… the mysql codes needed to store these bytes). If you have an average of 100 words per docid this means that reversed… regular reversed index vs vectorbased storage but also how the search itself will be performed is changed. With a regular lookup table… common words found in the database, linux 2.6 and mysql 4.1.18 was used in all cases – SQL_NO…
Post: ORDER BY ... LIMIT Performance Optimization
September 1, 2006 By 100 Comments
…) but MySQL can’t do it at this point. Workaround which can be currently used is separate column which holds reverse values, so you can do ORDER BY col1, col2_reverse instead. Beware of large LIMIT… ether extending your indexes so MySQL Optimizer does not have to chose between better sort or better lookup or use FORCE INDEX…
Post: Why Index could refuse to work ?
September 8, 2006 By 15 Comments
… use the index. Lets check if your guess is right: mysql> explain select * from article where article_id=”10″; +—-+————-+———+——+—————+———+———+——-+——+————-+ | id | select… ask why MySQL can’t use index in this case, simply by converting number to the string and performing index lookup ? This… in reverse one. To add confusion MySQL mentions key as “possible keys” while really it has no way to use it for lookup…
