From 6ddba9b46c1d307ea7e03d753d0988183b9cb80c Mon Sep 17 00:00:00 2001 From: bogdanvlviv Date: Mon, 11 Dec 2017 23:56:07 +0200 Subject: Fix conflicts `counter_cache` with `touch: true` by optimistic locking. ``` # create_table :posts do |t| # t.integer :comments_count, default: 0 # t.integer :lock_version # t.timestamps # end class Post < ApplicationRecord end # create_table :comments do |t| # t.belongs_to :post # end class Comment < ApplicationRecord belongs_to :post, touch: true, counter_cache: true end ``` Before: ``` post = Post.create! # => begin transaction INSERT INTO "posts" ("created_at", "updated_at", "lock_version") VALUES ("2017-12-11 21:27:11.387397", "2017-12-11 21:27:11.387397", 0) commit transaction comment = Comment.create!(post: post) # => begin transaction INSERT INTO "comments" ("post_id") VALUES (1) UPDATE "posts" SET "comments_count" = COALESCE("comments_count", 0) + 1, "lock_version" = COALESCE("lock_version", 0) + 1 WHERE "posts"."id" = 1 UPDATE "posts" SET "updated_at" = '2017-12-11 21:27:11.398330', "lock_version" = 1 WHERE "posts"."id" = 1 AND "posts"."lock_version" = 0 rollback transaction # => ActiveRecord::StaleObjectError: Attempted to touch a stale object: Post. Comment.take.destroy! # => begin transaction DELETE FROM "comments" WHERE "comments"."id" = 1 UPDATE "posts" SET "comments_count" = COALESCE("comments_count", 0) - 1, "lock_version" = COALESCE("lock_version", 0) + 1 WHERE "posts"."id" = 1 UPDATE "posts" SET "updated_at" = '2017-12-11 21:42:47.785901', "lock_version" = 1 WHERE "posts"."id" = 1 AND "posts"."lock_version" = 0 rollback transaction # => ActiveRecord::StaleObjectError: Attempted to touch a stale object: Post. ``` After: ``` post = Post.create! # => begin transaction INSERT INTO "posts" ("created_at", "updated_at", "lock_version") VALUES ("2017-12-11 21:27:11.387397", "2017-12-11 21:27:11.387397", 0) commit transaction comment = Comment.create!(post: post) # => begin transaction INSERT INTO "comments" ("post_id") VALUES (1) UPDATE "posts" SET "comments_count" = COALESCE("comments_count", 0) + 1, "lock_version" = COALESCE("lock_version", 0) + 1, "updated_at" = '2017-12-11 21:37:09.802642' WHERE "posts"."id" = 1 commit transaction comment.destroy! # => begin transaction DELETE FROM "comments" WHERE "comments"."id" = 1 UPDATE "posts" SET "comments_count" = COALESCE("comments_count", 0) - 1, "lock_version" = COALESCE("lock_version", 0) + 1, "updated_at" = '2017-12-11 21:39:02.685520' WHERE "posts"."id" = 1 commit transaction ``` Fixes #31199. --- activerecord/CHANGELOG.md | 83 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 83 insertions(+) (limited to 'activerecord/CHANGELOG.md') diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md index 89a12d4223..ceef240257 100644 --- a/activerecord/CHANGELOG.md +++ b/activerecord/CHANGELOG.md @@ -1,3 +1,86 @@ +* Fix conflicts `counter_cache` with `touch: true` by optimistic locking. + + ``` + # create_table :posts do |t| + # t.integer :comments_count, default: 0 + # t.integer :lock_version + # t.timestamps + # end + class Post < ApplicationRecord + end + + # create_table :comments do |t| + # t.belongs_to :post + # end + class Comment < ApplicationRecord + belongs_to :post, touch: true, counter_cache: true + end + ``` + + Before: + ``` + post = Post.create! + # => begin transaction + INSERT INTO "posts" ("created_at", "updated_at", "lock_version") + VALUES ("2017-12-11 21:27:11.387397", "2017-12-11 21:27:11.387397", 0) + commit transaction + + comment = Comment.create!(post: post) + # => begin transaction + INSERT INTO "comments" ("post_id") VALUES (1) + + UPDATE "posts" SET "comments_count" = COALESCE("comments_count", 0) + 1, + "lock_version" = COALESCE("lock_version", 0) + 1 WHERE "posts"."id" = 1 + + UPDATE "posts" SET "updated_at" = '2017-12-11 21:27:11.398330', + "lock_version" = 1 WHERE "posts"."id" = 1 AND "posts"."lock_version" = 0 + rollback transaction + # => ActiveRecord::StaleObjectError: Attempted to touch a stale object: Post. + + Comment.take.destroy! + # => begin transaction + DELETE FROM "comments" WHERE "comments"."id" = 1 + + UPDATE "posts" SET "comments_count" = COALESCE("comments_count", 0) - 1, + "lock_version" = COALESCE("lock_version", 0) + 1 WHERE "posts"."id" = 1 + + UPDATE "posts" SET "updated_at" = '2017-12-11 21:42:47.785901', + "lock_version" = 1 WHERE "posts"."id" = 1 AND "posts"."lock_version" = 0 + rollback transaction + # => ActiveRecord::StaleObjectError: Attempted to touch a stale object: Post. + ``` + + After: + ``` + post = Post.create! + # => begin transaction + INSERT INTO "posts" ("created_at", "updated_at", "lock_version") + VALUES ("2017-12-11 21:27:11.387397", "2017-12-11 21:27:11.387397", 0) + commit transaction + + comment = Comment.create!(post: post) + # => begin transaction + INSERT INTO "comments" ("post_id") VALUES (1) + + UPDATE "posts" SET "comments_count" = COALESCE("comments_count", 0) + 1, + "lock_version" = COALESCE("lock_version", 0) + 1, + "updated_at" = '2017-12-11 21:37:09.802642' WHERE "posts"."id" = 1 + commit transaction + + comment.destroy! + # => begin transaction + DELETE FROM "comments" WHERE "comments"."id" = 1 + + UPDATE "posts" SET "comments_count" = COALESCE("comments_count", 0) - 1, + "lock_version" = COALESCE("lock_version", 0) + 1, + "updated_at" = '2017-12-11 21:39:02.685520' WHERE "posts"."id" = 1 + commit transaction + ``` + + Fixes #31199. + + *bogdanvlviv* + * Add support for PostgreSQL operator classes to `add_index`. 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