Arvados

Inspired by #21737

This is what the full search indexes on (the operation is building a string with all the fields separated by spaces and then indexing on that):

CREATE INDEX collections_trgm_text_search_idx ON public.collections USING gin (((((((((((((((((((
  COALESCE(owner_uuid, ''::character varying))::text || ' '::text) || (
  COALESCE(modified_by_client_uuid, ''::character varying))::text) || ' '::text) || (
  COALESCE(modified_by_user_uuid, ''::character varying))::text) || ' '::text) || (
  COALESCE(portable_data_hash, ''::character varying))::text) || ' '::text) || (
  COALESCE(uuid, ''::character varying))::text) || ' '::text) || (
  COALESCE(name, ''::character varying))::text) || ' '::text) || (
  COALESCE(description, ''::character varying))::text) || ' '::text) || 
  COALESCE((properties)::text, ''::text)) || ' '::text) || 
  COALESCE(file_names, ''::text)))
gin_trgm_ops)

Looking at this, I think it would be much better if all uuid fields and the portable data hash were excluded.

The reasoning is that uuids and the PDH are a string of random alphanumeric characters, generating a lot of trigrams which become potential matches, but not actual matches.

Task:

1. exclude portable_data_hash and any field ending _uuid from full_text_searchable_columns
2. add a migration that recreates the trigram indexes for each table with the new full_text_coalesce