… by Gokhan inspired me to write a bit about descending indexes and about loose index scan, or what Gokhan calls “better range” support… (for packed indexes) may have reverse scan being much slower than forward scan. So when do you really need Descending indexes ? Most typical… in your comments please also explain which indexes do you have on the table. SHOW CREATE TABLE is the best. Otherwise I…
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 you mentioned the… use, which means maybe there is a better way then creating a ‘negative value’ column or something that I could sort…
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 19 Comments
… table scans and index scans more efficient. I can’t wait for ability to create physically sorted indexes with Innodb (with index built by… single extent. For big tables, a secondary index reserves different extents from the clustered index. Q4: Does Innodb ever merges sequential pages… extent where the next index page in the ascending order is. InnoDB has a similar heuristic for descending index scans. The InnoDB sequential…
Post: ORDER BY ... LIMIT Performance Optimization
September 1, 2006 By 100 Comments
… SELECT * FROM sites ORDER BY date_created DESC LIMIT 10; I would use index on (date_created) to get result set very fast… in the list now so index on (category_id, date_created) can’t be used directly. Index on date_created separately would still work… for this would be to have index which is sorted appropriately (ascending by col1 and descending by col2) but MySQL can’t…
