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| author | David Celis <me@davidcel.is> | 2013-05-09 20:31:31 +0530 |
|---|---|---|
| committer | David Celis <me@davidcel.is> | 2013-06-07 10:16:59 -0700 |
| commit | 4e2bec383239f9ab3493208ef3bad1f2cbea3c93 (patch) | |
| tree | aa7c08c45b9cc6ee85a3f896c0f6cf23300ef8cb /guides | |
| parent | 94725b81f5588e4b0f43222c4f142c3135941b4b (diff) | |
| download | rails-4e2bec383239f9ab3493208ef3bad1f2cbea3c93.tar.gz rails-4e2bec383239f9ab3493208ef3bad1f2cbea3c93.tar.bz2 rails-4e2bec383239f9ab3493208ef3bad1f2cbea3c93.zip | |
ActiveRecord::Relation#blank? should `LIMIT 1`
This is an SQL improvement to ActiveRecord::Relation#blank?. Currently,
it calls `to_a` on the Relation, which loads all records in the
association, and calls `blank?` on the loaded Array. There are other
ways, however, to check the emptiness of an association that are far
more performant. `#empty?`, `#exists?` and `#any?` all attach a `LIMIT
1` to the SQL query before firing it off, which is a nice query
improvement. `#blank?` should do the same!
Bonus performance improvements will also happen for `#present?`, which
merely calls the negation of `#blank?`
Signed-off-by: David Celis <me@davidcel.is>
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