chore(sql): add sql migration script to remove isSearchable

src/server/db_migrations/20201116_remove_isSearchable.sql

@@ -0,0 +1,22 @@
+-- This migration script removes Urls.isSearchable with a default
+-- of true and changes the index to index unconditionally
+-- sql statements in scripts/ should be run to update functions too
+BEGIN TRANSACTION;
+
+-- Set "isSearchable" in url_histories to be false
+ALTER TABLE url_histories DROP COLUMN "isSearchable";
+ALTER TABLE urls DROP COLUMN "isSearchable";
+
+
+DROP INDEX IF EXISTS urls_weighted_search_idx;
+
+-- Search will be run on a concatenation of vectors formed from short links and their
+-- description. Descriptions are given a lower weight than short links as short link
+-- words can be taken as the title and words there are likely to be more important than
+-- those in their corresponding description.
+-- Search queries will have to use this exact expresion to be able to utilize the index.
+CREATE INDEX urls_weighted_search_idx ON urls USING gin ((setweight(to_tsvector(
+'english', urls."shortUrl"), 'A') || setweight(to_tsvector('english',
+urls."description"), 'B')));
+
+COMMIT;