… used is: select l_orderkey, sum(l_extendedprice * (1 – l_discount)) as revenue, o_orderdate, o_shippriority from customer, orders, lineitem FORCE INDEX… should be increased appropriately for the best possible performance gain. This is not entirely visible in the manual either for MariaDB or MySQL…
Post: Index Condition Pushdown in MySQL 5.6 and MariaDB 5.5 and its performance impact
March 12, 2012 By 12 Comments
… is aimed at a new optimizer enhancement Index Condition Pushdown (ICP). Its available in both MySQL 5.6 and MariaDB 5.5… aimed at. Index Condition Pushdown Traditional B-Tree index lookups have some limitations in cases such as range scans, where index parts after the part on which range condition is applied cannot be used for filtering records. For…
Post: High-Performance Click Analysis with MySQL
December 22, 2008 By 13 Comments
…not only will every index be a little narrower, the table will now contain only half as many rows. That will make the indexes…be hard work there too, assuming you use statement-based replication. You can save that work by either using MySQL… brute-forcing a solution that really needs to be solved with…
Post: ORDER BY ... LIMIT Performance Optimization
September 1, 2006 By 93 Comments
…from the index can be used to satisfy order by, index however will not be helpful to check c=5 (unless it is index covered query). Index …extending your indexes so MySQL Optimizer does not have to chose between better sort or better lookup or use FORCE INDEX to force it to use appropriate index. One…
Post: Getting MySQL to use full key length
January 31, 2007 By 5 Comments
… does not help, at least in this case. However looks like as one of its side effects FORCE INDEX actually forces index to be used to largest extent possible: mysql> explain SELECT thread_id FROM nn2_msg132.msg132 force index(group_id) …
Post: Why Index could refuse to work ?
September 8, 2006 By 13 Comments
… the earth index would not be used you would think, even if MySQL is mentioning it in “possible keys” ? Should you try to force it ? mysql> explain select * from article force index…
Post: Extending Index for Innodb tables can hurt performance in a surprising way
May 22, 2010 By 9 Comments
… which can use index can also use prefix of the new index are they ? It turns there are special cases when this is not the… you will need to use FORCE INDEX(a) to force MySQL optimizer using right plan. These results mean you should be very careful applying index changes from mk…
Post: Multi Column indexes vs Index Merge
September 19, 2009 By 30 Comments
… can’t be more than if only index prefix is used. MySQL does not know it as it looks at stats from different indexes independently not trying… do not know of the hint in MySQL which would allow forcing using index merge when MySQL does not think it should be used. I hope hint would be added…
Post: Troubleshooting MySQL Upgrade Performance Regressions
February 15, 2012 By Leave a Comment
… MySQL Servers side by side (for example with MySQL Sandbox) can especially be …using hints such as STRAIGHT_JOIN, FORCE INDEX, BIG_RESULT/SMALL_RESULT. Check whatever stats are the same (run SHOW INDEXES…not be able to get new version to pick the old plan no matter how you try and you might be forced…
Post: Connecting orphaned .ibd files
May 13, 2011 By 12 Comments
…2. ibdata1 is heavily corrupted and innodb_force_recovery doesn’t help Chris Calender suggests…INDEXES: CREATE TABLE `SYS_INDEXES` ( `TABLE_ID` bigint(20) unsigned NOT NULL default ’0′, `ID` bigint(20) unsigned NOT…reason it shold not be used in production. The tool ibdconnect was tested on MySQL 5.1 …
