… you can have, which is 64 per table in recent MySQL versions. However it is often too many. … the same table, not other index, also you only can have equality comparison as a search condition WHERE … you will need to use something like Trick “Unionizing Order by” described in presentation. Q: what is…
Post: The Optimization That (Often) Isn't: Index Merge Intersection
December 14, 2012 By 6 Comments
…_colB = Y” might use the index merge union algorithm, which would *simultaneously* (this is … 1. row *************************** id: 1 select_type: SIMPLE table: users type: index_merge possible_keys:…not look too bad. MySQL is using three different indexes to search approximately 8100 out…
Post: MySQL: Data Storage or Data Processing
November 18, 2007 By 9 Comments
…MySQL. When it comes to large scale data processing other techniques are used. Google uses some bigtable based technologies for search…unions/instersections have to be performed on the SQL node. May be MySQL…
Post: ORDER BY ... LIMIT Performance Optimization
September 1, 2006 By 100 Comments
… be UNION workaround I already wrote about. So what if you have application which can perform search on…high end custom search solutions can be developed, but if we stick to simple MySQL using multiple indexes…optimized even if it is done by second table: mysql> explain select test.i from test, test t…
Comment: Using delayed JOIN to optimize count(*) and LIMIT queries
April 16, 2007 By 22 Comments
… “lower” characters ! Yes I often use this too, in MySQL and in Postgres, it is just one of …yourself is the way. Recently I had a huge search query (in Postgres) which was horrendously slow. It …, and the all-time favourite, union from a huge archive table and an active table, plus a 5-way JOIN with…
Comment: How to find wrong indexing with glance view
August 23, 2008 By 27 Comments
… to users so can be all stored in users table(may be except looking_for, but let’s keep… use it everywhere as peter suggested as 90% of searches will use one either ‘male’ or ‘female’ and it…/2006/08/10/using-union-to-implement-loose-index-scan-to-mysql/#comment-1695 2. http://dev.mysql.com/doc/refman…
Comment: Using delayed JOIN to optimize count(*) and LIMIT queries
April 16, 2007 By 22 Comments
… I often use this too, in MySQL and in Postgres, it is just one of the tricks…it yourself is the way. Recently I had a huge search query (in Postgres) which was horrendously slow. It has … etc, and the all-time favourite, union from a huge archive table and an active table, plus a 5-way JOIN with a…
