As pointed out by https://github.com/mastodon/mastodon/pull/21297#discussion_r1028372193
at least one of our dependencies already dropped support for Ruby 2.6, and we
had removed Ruby 2.6 tests from the CI over a year ago (#16861).
So stop advertising Ruby 2.6 support, bump targeted version, and drop some
compatibility code.
* refactor(statuses_vacuum): remove dead code - unused
Method is not called inside class and private.
Clean up dead code.
* refactor(statuses_vacuum): make retention_period present test explicit
This private method only hides functionality.
It is best practice to be as explicit as possible.
* refactor(statuses_vacuum): improve query performance
- fix statuses_scope having sub-select for Account.remote scope by
`joins(:account).merge(Account.remote)`
- fix statuses_scope unnecessary use of `Status.arel_table[:id].lt`
because it is inexplicit, bad practice and even slower than normal
`.where('statuses.id < ?'`
- fix statuses_scope remove select(:id, :visibility) for having reusable
active record query batches (no re queries)
- fix vacuum_statuses! to use in_batches instead of find_in_batches,
because in_batches delivers a full blown active record query result,
in stead of an array - no requeries necessary
- send(:unlink_from_conversations) not to perform another db query, but
reuse the in_batches result instead.
- remove now obsolete remove_from_account_conversations method
- remove_from_search_index uses array of ids, instead of mapping
the ids from an array - this should be more efficient
- use the in_batches scope to call delete_all, instead of running
another db query for this - because it is again more efficient
- add TODO comment for calling models private method with send
* refactor(status): simplify unlink_from_conversations
- add `has_many through:` relation mentioned_accounts
- use model scope local instead of method call `Status#local?`
- more readable add account to inbox_owners when account.local?
* refactor(status): searchable_by way less sub selects
These queries all included a sub-select. Doing the same with a joins
should be more efficient.
Since this method does 5 such queries, this should be significant,
since it technically halves the query count.
This is how it was:
```ruby
[3] pry(main)> Status.first.mentions.where(account: Account.local, silent: false).explain
Status Load (1.6ms) SELECT "statuses".* FROM "statuses" WHERE "statuses"."deleted_at" IS NULL ORDER BY "statuses"."id" DESC LIMIT $1 [["LIMIT", 1]]
Mention Load (1.5ms) SELECT "mentions".* FROM "mentions" WHERE "mentions"."status_id" = $1 AND "mentions"."account_id" IN (SELECT "accounts"."id" FROM "accounts" WHERE "accounts"."domain" IS NULL) AND "mentions"."silent" = $2 [["status_id", 109382923142288414], ["silent", false]]
=> EXPLAIN for: SELECT "mentions".* FROM "mentions" WHERE "mentions"."status_id" = $1 AND "mentions"."account_id" IN (SELECT "accounts"."id" FROM "accounts" WHERE "accounts"."domain" IS NULL) AND "mentions"."silent" = $2 [["status_id", 109382923142288414], ["silent", false]]
QUERY PLAN
------------------------------------------------------------------------------------------------------------------
Nested Loop (cost=0.15..23.08 rows=1 width=41)
-> Seq Scan on accounts (cost=0.00..10.90 rows=1 width=8)
Filter: (domain IS NULL)
-> Index Scan using index_mentions_on_account_id_and_status_id on mentions (cost=0.15..8.17 rows=1 width=41)
Index Cond: ((account_id = accounts.id) AND (status_id = '109382923142288414'::bigint))
Filter: (NOT silent)
(6 rows)
```
This is how it is with this change:
```ruby
[4] pry(main)> Status.first.mentions.joins(:account).merge(Account.local).active.explain
Status Load (1.7ms) SELECT "statuses".* FROM "statuses" WHERE "statuses"."deleted_at" IS NULL ORDER BY "statuses"."id" DESC LIMIT $1 [["LIMIT", 1]]
Mention Load (0.7ms) SELECT "mentions".* FROM "mentions" INNER JOIN "accounts" ON "accounts"."id" = "mentions"."account_id" WHERE "mentions"."status_id" = $1 AND "accounts"."domain" IS NULL AND "mentions"."silent" = $2 [["status_id", 109382923142288414], ["silent", false]]
=> EXPLAIN for: SELECT "mentions".* FROM "mentions" INNER JOIN "accounts" ON "accounts"."id" = "mentions"."account_id" WHERE "mentions"."status_id" = $1 AND "accounts"."domain" IS NULL AND "mentions"."silent" = $2 [["status_id", 109382923142288414], ["silent", false]]
QUERY PLAN
------------------------------------------------------------------------------------------------------------------
Nested Loop (cost=0.15..23.08 rows=1 width=41)
-> Seq Scan on accounts (cost=0.00..10.90 rows=1 width=8)
Filter: (domain IS NULL)
-> Index Scan using index_mentions_on_account_id_and_status_id on mentions (cost=0.15..8.17 rows=1 width=41)
Index Cond: ((account_id = accounts.id) AND (status_id = '109382923142288414'::bigint))
Filter: (NOT silent)
(6 rows)
```
When a poll is edited, we reset the poll and remove all previous
votes. However, prior to this commit, the voter count on the poll
was not reset. This leads to incorrect percentages being shown in
poll results.
Fixes#21696
