… two Intel(R) Xeon(R) CPU E5-2450 0 @ 2.10GHz, 48GB of…size. Now to see this point of intersection, let’s review different workload (which…4M thread_cache_size = 1000 query_cache_size = 0 query_cache_type = 0 ft_min_word…threads = 1 myisam_recover socket=/var/lib/mysql/mysql.sock user=root skip-grant-…
Post: The Optimization That (Often) Isn't: Index Merge Intersection
December 14, 2012 By 6 Comments
… certain types of queries which contain WHERE clauses with columns that had single-column indexes on them, MySQL could sometimes make use of the…-theoretic union of the two result sets. Replace that “OR” with an “AND” and you might see the set-theoretic intersection of the result…
Comment: How to find wrong indexing with glance view
August 23, 2008 By 27 Comments
…, looking_for, location; integer – age 3) All queries fall into X IN (…) AND Y IN …intersection of multiple accesses by indexes. When we talk about index_merge_intersection, we should understand that mysql… (City, Gender, Age, Available). So mysql can choose between two which is more selective. 3…
Comment: Full text search for all MySQL Storage Engines
June 29, 2006 By 37 Comments
… about MySQL performance you’re right. There are two pieces which slow things down. First finding the rows which contain all keywords. Intersection of pretty large sets needs to be performed. Next problem is sorting – it is done by MySQL rather than full… it looks like what you need. Also benchmark using real queries from your site might be very interesting 
Comment: Multi Column indexes vs Index Merge
May 10, 2012 By 31 Comments
… merge (intersect). Below are two explains that I executed for the same SQL query with a couple of mins gap on the same mysql prod instance . The first SQL query executed in 0.03 secs whereas the second SQL query…
Post: Multiple column index vs multiple indexes
August 22, 2008 By 13 Comments
… on Multiple Indexes vs Two Column Index efficiency. I mentioned in most cases when query can use both of the ways using multiple… appropriately. To remove the overhead of starting MySQL etc from equation I also measured execution of “SELECT 1″ query using same script and subtracted… is also worth to watchout a MySQL may decide not to do Index merge (either intersection or union) but instead do full…
