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Diffstat (limited to 'guides/source/active_record_querying.md')
| -rw-r--r-- | guides/source/active_record_querying.md | 15 |
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diff --git a/guides/source/active_record_querying.md b/guides/source/active_record_querying.md index e40f16e62d..5fb030fad4 100644 --- a/guides/source/active_record_querying.md +++ b/guides/source/active_record_querying.md @@ -1821,6 +1821,21 @@ Client.limit(1).pluck(:name) # => ["David"] ``` +NOTE: You should also know that using `pluck` will trigger eager loading if the relation object contains include values, even if the eager loading is not necessary for the query. For example: + +```ruby +# store association for reusing it +assoc = Company.includes(:account) +assoc.pluck(:id) +# SELECT "companies"."id" FROM "companies" LEFT OUTER JOIN "accounts" ON "accounts"."id" = "companies"."account_id" +``` + +One way to avoid this is to `unscope` the includes: + +```ruby +assoc.unscope(:includes).pluck(:id) +``` + ### `ids` `ids` can be used to pluck all the IDs for the relation using the table's primary key. |