Improve index on statuses for api/v1/accounts account_id statuses (#7476)

Queries with the combination of account_id, id, and visibility can be
categorized in three types:
1. Querying for public and unlisted to enumerate statuses visible to
anyone.
2. Querying for public, unlisted, and private to enumerate statuses
visible to follower.
3. Querying for direct to enumerate own direct statuses.

1 and 2 is covered by the index with condition 'visibility IN (0, 1, 2)'.
It would bring better performance in case that there are many direct
statuses.

The index with condition 'visibility = 3' is just for 3. It would be much
faster to query direct statuses thanks to this query.

The total size of those two indexes are expected to be smaller than the
deleted one because they are partial and does not have to cover all the
table.

diff --git a/db/migrate/20180514130000_improve_index_on_statuses_for_api_v1_accounts_account_id_statuses.rb b/db/migrate/20180514130000_improve_index_on_statuses_for_api_v1_accounts_account_id_statuses.rb
new file mode 100644 (file)
index 0000000..2573bdf
--- /dev/null
+++ b/db/migrate/20180514130000_improve_index_on_statuses_for_api_v1_accounts_account_id_statuses.rb
@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+class ImproveIndexOnStatusesForApiV1AccountsAccountIdStatuses < ActiveRecord::Migration[5.1]
+  disable_ddl_transaction!
+
+  def change
+    add_index :statuses, [:account_id, :id, :visibility], where: 'visibility IN (0, 1, 2)', algorithm: :concurrently
+    add_index :statuses, [:account_id, :id], where: 'visibility = 3', algorithm: :concurrently
+    remove_index :statuses, column: [:account_id, :id, :visibility, :updated_at], order: { id: :desc }, algorithm: :concurrently, name: :index_statuses_20180106
+  end
+end

diff --git a/db/schema.rb b/db/schema.rb
index 221c08d98e48e44a7d1eed80ffcdf74b3abbb839..5bfc4df04b65c25f7e647dedddbd1e532cd4b4a5 100644 (file)
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2018_05_10_230049) do
+ActiveRecord::Schema.define(version: 2018_05_14_130000) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -447,7 +447,8 @@ ActiveRecord::Schema.define(version: 2018_05_10_230049) do
     t.bigint "account_id", null: false
     t.bigint "application_id"
     t.bigint "in_reply_to_account_id"
-    t.index ["account_id", "id", "visibility", "updated_at"], name: "index_statuses_20180106", order: { id: :desc }
+    t.index ["account_id", "id", "visibility"], name: "index_statuses_on_account_id_and_id_and_visibility", where: "(visibility = ANY (ARRAY[0, 1, 2]))"
+    t.index ["account_id", "id"], name: "index_statuses_on_account_id_and_id", where: "(visibility = 3)"
     t.index ["conversation_id"], name: "index_statuses_on_conversation_id"
     t.index ["in_reply_to_id"], name: "index_statuses_on_in_reply_to_id"
     t.index ["reblog_of_id", "account_id"], name: "index_statuses_on_reblog_of_id_and_account_id"