Add tsvector index to comments.body_markdown (#13469)

* Add tsvector index to comments.body_markdown

* Users --> Comments

db/migrate/20210421190438_add_body_markdown_tsvector_index_to_comments.rb

@@ -0,0 +1,27 @@
+class AddBodyMarkdownTsvectorIndexToComments < ActiveRecord::Migration[6.1]
+  disable_ddl_transaction!
+
+  INDEX = "to_tsvector('simple'::regconfig, COALESCE((body_markdown)::text, ''::text))"
+  private_constant :INDEX
+
+  INDEX_NAME = "index_comments_on_body_markdown_as_tsvector"
+  private_constant :INDEX_NAME
+
+  def up
+    return if index_name_exists?(:comments, INDEX_NAME)
+
+    add_index :comments,
+              INDEX,
+              using: :gin,
+              name: INDEX_NAME,
+              algorithm: :concurrently
+  end
+
+  def down
+    return unless index_name_exists?(:comments, INDEX_NAME)
+
+    remove_index :comments,
+                 name: INDEX_NAME,
+                 algorithm: :concurrently
+  end
+end

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: 2021_04_20_135208) do
+ActiveRecord::Schema.define(version: 2021_04_21_190438) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "citext"
@@ -388,6 +388,7 @@ ActiveRecord::Schema.define(version: 2021_04_20_135208) do
     t.datetime "updated_at", null: false
     t.bigint "user_id"
     t.index "digest(body_markdown, 'sha512'::text), user_id, ancestry, commentable_id, commentable_type", name: "index_comments_on_body_markdown_user_ancestry_commentable", unique: true
+    t.index "to_tsvector('simple'::regconfig, COALESCE(body_markdown, ''::text))", name: "index_comments_on_body_markdown_as_tsvector", using: :gin
     t.index ["ancestry"], name: "index_comments_on_ancestry"
     t.index ["ancestry"], name: "index_comments_on_ancestry_trgm", opclass: :gin_trgm_ops, using: :gin
     t.index ["commentable_id", "commentable_type"], name: "index_comments_on_commentable_id_and_commentable_type"