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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.
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1 parent a5b362d commit 1be9830d4d99e2bf56f1cadf74b843f22d66da35 @fxn fxn committed Nov 25, 2011
@@ -1,3 +1,4 @@
+# -*- coding: utf-8 -*-
require 'active_support/core_ext/object/blank'
require 'active_support/core_ext/module/delegation'
@@ -155,8 +156,8 @@ def explain
end
queries.map do |sql|
- @klass.connection.explain(sql)
- end.join
+ "EXPLAIN for: #{sql}\n#{@klass.connection.explain(sql)}"
+ end.join("\n")
end
def to_a
@@ -9,12 +9,15 @@ class ExplainTest < ActiveRecord::TestCase
def test_explain_for_one_query
explain = Developer.where(:id => 1).explain
+ assert_match %(EXPLAIN for: SELECT `developers`.* FROM `developers` WHERE `developers`.`id` = 1), explain
assert_match %(developers | const), explain
end
def test_explain_with_eager_loading
explain = Developer.where(:id => 1).includes(:audit_logs).explain
+ assert_match %(EXPLAIN for: SELECT `developers`.* FROM `developers` WHERE `developers`.`id` = 1), explain
assert_match %(developers | const), explain
+ assert_match %(EXPLAIN for: SELECT `audit_logs`.* FROM `audit_logs` WHERE `audit_logs`.`developer_id` IN (1)), explain
assert_match %(audit_logs | ALL), explain
end
end
@@ -9,14 +9,17 @@ class ExplainTest < ActiveRecord::TestCase
def test_explain_for_one_query
explain = Developer.where(:id => 1).explain
+ assert_match %(EXPLAIN for: SELECT "developers".* FROM "developers" WHERE "developers"."id" = 1), explain
assert_match %(QUERY PLAN), explain
assert_match %(Index Scan using developers_pkey on developers), explain
end
def test_explain_with_eager_loading
explain = Developer.where(:id => 1).includes(:audit_logs).explain
assert_match %(QUERY PLAN), explain
+ assert_match %(EXPLAIN for: SELECT "developers".* FROM "developers" WHERE "developers"."id" = 1), explain
assert_match %(Index Scan using developers_pkey on developers), explain
+ assert_match %(EXPLAIN for: SELECT "audit_logs".* FROM "audit_logs" WHERE "audit_logs"."developer_id" IN (1)), explain
assert_match %(Seq Scan on audit_logs), explain
end
end
@@ -9,12 +9,15 @@ class ExplainTest < ActiveRecord::TestCase
def test_explain_for_one_query
explain = Developer.where(:id => 1).explain
+ assert_match %(EXPLAIN for: SELECT "developers".* FROM "developers" WHERE "developers"."id" = 1), explain
assert_match(/(SEARCH )?TABLE developers USING (INTEGER )?PRIMARY KEY/, explain)
end
def test_explain_with_eager_loading
explain = Developer.where(:id => 1).includes(:audit_logs).explain
+ assert_match %(EXPLAIN for: SELECT "developers".* FROM "developers" WHERE "developers"."id" = 1), explain
assert_match(/(SEARCH )?TABLE developers USING (INTEGER )?PRIMARY KEY/, explain)
+ assert_match %(EXPLAIN for: SELECT "audit_logs".* FROM "audit_logs" WHERE "audit_logs"."developer_id" IN (1)), explain
assert_match(/(SCAN )?TABLE audit_logs/, explain)
end
end
@@ -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>

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