Only index up to 32KB of search content

To prevent overflowing the columns in the search index tables (and also
just to avoid creating massive indexes), let's limit the searchable
content to the first 32KB.

app/models/concerns/searchable.rb

@@ -1,6 +1,8 @@
 module Searchable
   extend ActiveSupport::Concern
 
+  SEARCH_CONTENT_LIMIT = 32.kilobytes
+
   included do
     after_create_commit :create_in_search_index
     after_update_commit :update_in_search_index
@@ -32,11 +34,15 @@ module Searchable
         card_id: search_card_id,
         board_id: search_board_id,
         title: search_title,
-        content: search_content,
+        content: search_record_content,
         created_at: created_at
       }
     end
 
+    def search_record_content
+      search_content&.truncate_bytes(SEARCH_CONTENT_LIMIT, omission: "")
+    end
+
     def search_record_class
       Search::Record.for(account_id)
     end

test/models/card/searchable_test.rb

@@ -32,6 +32,24 @@ class Card::SearchableTest < ActiveSupport::TestCase
     assert_not_includes results, card_in_other_board
   end
 
+  test "search content is truncated to a reasonable limit" do
+    search_record_class = Search::Record.for(@user.account_id)
+
+    # Create a card with unreasonably long content
+    long_content = "asdf " * Searchable::SEARCH_CONTENT_LIMIT
+    card = @board.cards.create!(title: "Card with long description", creator: @user)
+    card.description = ActionText::Content.new(long_content)
+    card.save!
+
+    # Check if was indexed
+    results = Card.mentioning("asdf", user: @user)
+    assert_includes results, card
+
+    # Check the content length was within the limit
+    search_record = search_record_class.find_by(searchable_type: "Card", searchable_id: card.id)
+    assert search_record.content.bytesize <= Searchable::SEARCH_CONTENT_LIMIT
+  end
+
   test "deleting card removes search record and FTS entry" do
     search_record_class = Search::Record.for(@user.account_id)
     card = @board.cards.create!(title: "Card to delete", creator: @user)