Slow varchar index performance in Postgres - postgresql

Question

I've got a table with ~500,000 rows with a column with values like Brutus, Dreamer of the Wanton Wasteland. I need to do a case-insensitive LIKE query on these, but it seems to perform very slowly. I tried making an index with:
create index name_idx on deck (name);
and
create index deck_name_idx on deck (lower(name));
But the query is equally slow either way. Here is my query:
select *
from deck
where lower(deck.name) like '%brutus, dreamer of the%'
order by deck.id desc
limit 20
Here are the results of my explain analyze (this is with the second index, but both are equally slow.)
Limit (cost=152534.89..152537.23 rows=20 width=1496) (actual time=627.480..627.490 rows=1 loops=1)
-> Gather Merge (cost=152534.89..152539.56 rows=40 width=1496) (actual time=627.479..627.488 rows=1 loops=1)
Workers Planned: 2
Workers Launched: 2
-> Sort (cost=151534.87..151534.92 rows=20 width=1496) (actual time=611.447..611.447 rows=0 loops=3)
Sort Key: id DESC
Sort Method: quicksort Memory: 25kB
-> Parallel Seq Scan on deck (cost=0.00..151534.44 rows=20 width=1496) (actual time=609.818..611.304 rows=0 loops=3)
Filter: (lower((name)::text) ~~ '%brutus, dreamer of the%'::text)
Rows Removed by Filter: 162210
Planning time: 0.786 ms
Execution time: 656.510 ms
Is there a better way to set up this index? If I have to I could denormalize the column to a lowercase version, but I'd rather not do that unless it will help a lot and there's no better way.

Answer 1

To support LIKE queries with no wildcard in the beginning, use
CREATE INDEX ON deck (lower(name) varchar_pattern_ops);
To support LIKE searches that can have a wildcard at the beginning, you can
CREATE EXTENSION pg_trgm;
CREATE INDEX ON deck USING gin (lower(name) gin_trgm_ops);