… by Gokhan inspired me to write a bit about descending indexes and about loose index scan, or what Gokhan calls “better range” support… general – these are features MySQL should get for all storage engines at some point. Descending indexes – This is something MySQL does not have at… (for packed indexes) may have reverse scan being much slower than forward scan. So when do you really need Descending indexes ? Most typical…
Comment: Descending indexing and loose index scan
June 20, 2006 By 6 Comments
…, because I have an index on (scraped,siteid), but as of MySQL 5.0.21 there is no descending index possible, so how would you suggest I manage the descending index? I noticed…
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 17 Comments
… can’t wait for ability to create physically sorted indexes with Innodb (with index built by sort) this is when this should… extent where the next index page in the ascending order is. InnoDB has a similar heuristic for descending index scans. The InnoDB sequential… additional throughput? HT: ha_innodb.cc in 5.1: static MYSQL_SYSVAR_ULONG(thread_concurrency, srv_thread_concurrency, PLUGIN_VAR_RQCMDARG…
Comment: My Innodb Feature wishes
May 9, 2006 By 30 Comments
… by Gokhan inspired me to write a bit about descending indexes and about loose index scan, or what Gokhan calls “better range” support… actially related to Innodb tables in general – these are features MySQL should get for all storage engines at some point. [...]
Comment: My Innodb Feature wishes
May 8, 2006 By 30 Comments
1. MySQL to open interface fulltext search and innoDB implement it. 2. Descending indexes. 3. Better index usage on range queries.
Comment: My Innodb Feature wishes
May 9, 2006 By 30 Comments
… post’s item 2 and 3. Item 2: I believe descending indexes would be helpful here since in the inner select i… max date when approaching the nearest exchange value. Item 3: MySQL does not use xdate in the inner select. It just…
Comment: Full text search for all MySQL Storage Engines
June 29, 2006 By 37 Comments
…. Vadim: Darn, what are the odds that mysql will use sphinx as its native fulltext index instead of todays version/edition ? 15… -l 200 –sort=date (in boolean mode sorting by date descending returning top 200 matches): — PROFILE — root: 8.81, self: 0… along with only -l 200 –sort=date (sorting by date descending (equal to my previous benchmark when there were no boolean…
Post: ORDER BY ... LIMIT Performance Optimization
September 1, 2006 By 93 Comments
… this would be to have index which is sorted appropriately (ascending by col1 and descending by col2) but MySQL can’t do it… long as it is indexed) Force index if needed In some cases MySQL Optimizer may prefer to use different index, which has better selectivity… extending your indexes so MySQL Optimizer does not have to chose between better sort or better lookup or use FORCE INDEX to force…
