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| author | Xavier Noria <fxn@hashref.com> | 2011-11-25 14:29:34 -0800 |
|---|---|---|
| committer | Xavier Noria <fxn@hashref.com> | 2011-11-25 14:29:34 -0800 |
| commit | 1be9830d4d99e2bf56f1cadf74b843f22d66da35 (patch) | |
| tree | f4acc78649b273bc1bf97fe4bb70e3ca9167ffbf /railties/guides/source/active_record_querying.textile | |
| parent | a5b362df567ed4a0167a83e9b8f00b9f614ac38b (diff) | |
| download | rails-1be9830d4d99e2bf56f1cadf74b843f22d66da35.tar.gz rails-1be9830d4d99e2bf56f1cadf74b843f22d66da35.tar.bz2 rails-1be9830d4d99e2bf56f1cadf74b843f22d66da35.zip | |
add the query to AR::Relation#explain output
Rationale: this is more readable if serveral queries
are involved in one call. Also, it will be possible
to let AR log EXPLAINs automatically in production
mode, where queries are not even around.
Diffstat (limited to 'railties/guides/source/active_record_querying.textile')
| -rw-r--r-- | railties/guides/source/active_record_querying.textile | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/railties/guides/source/active_record_querying.textile b/railties/guides/source/active_record_querying.textile index ad12dca7e8..0f1f6eba4c 100644 --- a/railties/guides/source/active_record_querying.textile +++ b/railties/guides/source/active_record_querying.textile @@ -1287,6 +1287,7 @@ User.where(:id => 1).joins(:posts).explain may yield <plain> +EXPLAIN for: SELECT `users`.* FROM `users` INNER JOIN `posts` ON `posts`.`user_id` = `users`.`id` WHERE `users`.`id` = 1 <plus>----<plus>-------------<plus>-------<plus>-------<plus>---------------<plus>---------<plus>---------<plus>-------<plus>------<plus>-------------<plus> | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | <plus>----<plus>-------------<plus>-------<plus>-------<plus>---------------<plus>---------<plus>---------<plus>-------<plus>------<plus>-------------<plus> @@ -1302,6 +1303,7 @@ Active Record performs a pretty printing that emulates the one of the database shells. So, the same query running with the PostgreSQL adapter would yield instead <plain> +EXPLAIN for: SELECT "users".* FROM "users" INNER JOIN "posts" ON "posts"."user_id" = "users"."id" WHERE "users"."id" = 1 QUERY PLAN ------------------------------------------------------------------------------ Nested Loop Left Join (cost=0.00..37.24 rows=8 width=0) @@ -1324,12 +1326,15 @@ User.where(:id => 1).includes(:posts).explain yields <plain> +EXPLAIN for: SELECT `users`.* FROM `users` WHERE `users`.`id` = 1 <plus>----<plus>-------------<plus>-------<plus>-------<plus>---------------<plus>---------<plus>---------<plus>-------<plus>------<plus>-------<plus> | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | <plus>----<plus>-------------<plus>-------<plus>-------<plus>---------------<plus>---------<plus>---------<plus>-------<plus>------<plus>-------<plus> | 1 | SIMPLE | users | const | PRIMARY | PRIMARY | 4 | const | 1 | | <plus>----<plus>-------------<plus>-------<plus>-------<plus>---------------<plus>---------<plus>---------<plus>-------<plus>------<plus>-------<plus> 1 row in set (0.00 sec) + +EXPLAIN for: SELECT `posts`.* FROM `posts` WHERE `posts`.`user_id` IN (1) <plus>----<plus>-------------<plus>-------<plus>------<plus>---------------<plus>------<plus>---------<plus>------<plus>------<plus>-------------<plus> | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | <plus>----<plus>-------------<plus>-------<plus>------<plus>---------------<plus>------<plus>---------<plus>------<plus>------<plus>-------------<plus> |