add index for sorting by word_count

packages/db/migrations/0157.do.library_item_user_id_word_count_idx.sql

@@ -0,0 +1,6 @@
+-- Type: DO
+-- Name: library_item_user_id_word_count_idx
+-- Description: Add library_item_user_id_word_count_idx index on library_item table for user_id and word_count
+
+-- create index for sorting concurrently to avoid locking
+CREATE INDEX CONCURRENTLY IF NOT EXISTS library_item_user_id_word_count_idx ON omnivore.library_item (user_id, word_count DESC NULLS LAST);

packages/db/migrations/0157.undo.library_item_user_id_word_count_idx.sql

@@ -0,0 +1,9 @@
+-- Type: UNDO
+-- Name: library_item_user_id_word_count_idx
+-- Description: Add library_item_user_id_word_count_idx index on library_item table for user_id and word_count
+
+BEGIN;
+
+DROP INDEX IF EXISTS library_item_user_id_word_count_idx;
+
+COMMIT;