On 20 Dec 2008, at 07:11, Marnen Laibow-Koser wrote:
> > > On Dec 20, 1:01 am, Jeff Pritchard <[email protected]> > wrote: >> Hi, >> I don't quite understand the syntax for database indexes and/or how >> the >> work to help speed up specific database searches. Can somebody >> suggest >> a set of indexs that would make this set of queries go faster? > [...] > > Very simple: you can profit by indexing on almost anything you're > going to be doing a lot of searching on. In this case, that means > that you should consider building indices on your foreign key fields > (such as contacts.user_id), since they're what you're searching on in > these queries. But before you do that, you might want to try EXPLAIN > SELECT on the queries you're interested in, and see what mySQL tells > you about where the bottlenecks are. > All of the above is good. To explain a little more if you do SELECT * from contacts where contacts.user_id = 2356 and there is no index then the database must examine every single row in the contacts table to see if it has the right user_id whereas if it has an index it can go straight there. (similar to how if you have a phone book and you're looking for all entries 'Michael smith' you don't have to read the entire phone book, you can jump to the appropriate page very quickly) Fred > Best, > -- > Marnen Laibow-Koser > [email protected] > http://www.marnen.org > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
