# Speeding up ActiveRecord Querying on very large joins?

**URL:** <https://discuss.rubyonrails.org/t/speeding-up-activerecord-querying-on-very-large-joins/44910>\
**Category:** rubyonrails-talk\
**Created:** [August 6, 2009, 9:05pm UTC](https://discuss.rubyonrails.org/t/speeding-up-activerecord-querying-on-very-large-joins/44910 "2009-08-06T21:05:22Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Frederick\_Cheung](https://sea2.discourse-cdn.com/rubyonrails/user_avatar/discuss.rubyonrails.org/frederick_cheung/32/3901_2.png) [@Frederick\_Cheung](https://discuss.rubyonrails.org/u/Frederick_Cheung)\
**Post date:** [August 6, 2009, 9:05pm UTC](https://discuss.rubyonrails.org/t/speeding-up-activerecord-querying-on-very-large-joins/44910/1 "2009-08-06T21:05:22Z")

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> The bottleneck begins to occur on offense = ... (around 30 ms) and then deepens on defense = ... (around 460 ms).
> 
> These are indeed large but everything listed here is absolutely required for my app to work. What can I do to optimize this?

First off use EXPLAIN ... in your database's the query browser/console to find out how database is executing your query. You may find that it's doing something really stupid or that there are indices missing.

Fred