… answers: Q: Can you compare the use of subqueries/multiple joins vs. multiple queries (e.g. temp tables)? For performance, it’s… tradeoff of this solution is that it requires storing another column, and reinitializing the sequence after making certain insert/update/delete… against multiple columns in a compound index, then the order would matter, and it would have to match the order of columns in the index…
Comment: Benchmarking Percona Server TokuDB vs InnoDB
May 7, 2013 By 32 Comments
… TokuDB is indexes. If you add multiple multi-column indexes the difference with InnoDB will be even more notable. Also it allows multiple clustering indexes that… and 4.x). It really shines on large tables and index scan like queries.
Post: Is Synchronous Replication right for your app?
May 14, 2013 By 18 Comments
…Innodb is a single row (well, the PRIMARY KEY index entry for that row). This means typically on a…It does NOT mean you can’t modify data on multiple cluster nodes simultaneously. You can. It does NOT set…In Example 2, above, how above moving the ‘joined’ column to the users_groups table so we don’t…
Post: Multiple column index vs multiple indexes
August 22, 2008 By 13 Comments
… about Index Merge on Multiple Indexes vs Two Column Index efficiency. I mentioned in most cases when query can use both of the ways using multiple column index…: For benchmarked queries we can see Multiple Column index beats Index Merge in all cases when such index can be used. It is also worth…
Post: Multi Column indexes vs Index Merge
September 19, 2009 By 31 Comments
… Index merge works much better than multiple column indexes. This is in case you’re using OR between the columns. In this case the combined index… combined index in this case. In case you’re using OR between columns – single column indexes are required for index merge to work and combined indexes…
Post: How to find wrong indexing with glance view
August 21, 2008 By 27 Comments
…. If you have queries with multiple column restrictions in WHERE clause you most likely will need to have multiple column indexes for optimal performance. But wait. Do not go ahead and index all combinations. This would likely…
Post: Should you name indexes while doing ALTER TABLE ?
May 28, 2008 By 10 Comments
… the indexes. Lets first speak about naming. If you do not specify index name MySQL will name index by the first column of index created, if there is such index already it will… names are not really helpful for multiple column indexes – you can’t easily see what is the index MySQL trying to use from explain…
Post: The Optimization That (Often) Isn't: Index Merge Intersection
December 14, 2012 By 6 Comments
… with columns that had single-column indexes on them, MySQL could sometimes make use of the multiple indexes. For instance, “SELECT foo FROM bar WHERE indexed_colA = X OR indexed…
Comment: How to find wrong indexing with glance view
August 22, 2008 By 27 Comments
… there are many cases where multiple column indexes don’t work. That’s all. By looking at the index structure alone you cannot draw… seems that we disagree on index merge versus multiple column index. I’m saying that I see index merge working when multiple column indexes don’t. You’re…
Comment: How to find wrong indexing with glance view
August 22, 2008 By 27 Comments
… you always need multiple column indexes but the fact it is quite typical there are some queries which will benefit from multiple column indexes. If I see all tables have only single column indexes this typically means someone does not know about multiple column indexes and how…
