Postgres can do indexes on expressions. (A bitmap scan over 2 rows may not be the most impressive example!) https://www.postgresql.org/docs/12/indexes-expressio

Postgres can do indexes on expressions. (A bitmap scan over 2 rows may not be the most impressive example!) https://www.postgresql.org/docs/12/indexes-expressional.html https://www.postgresql.org/docs/12/indexes-expressional.html foo=# create table foo(x TEXT); foo=# CREATE INDEX foo_r3 on foo (right(x,3)); foo=# INSERT INTO foo VALUES ('aaaaaaaaaaaaazzz'); foo=# INSERT INTO foo VALUES ('xxxxxxxaaa'); foo=# SELECT * FROM foo WHERE right(x,3) > 'fff'; x ------------------ aaaaaaaaaaaaazzz (1 row) foo=# EXPLAIN ANALYZE SELECT * FROM foo WHERE right(x,3) > 'fff'; QUERY PLAN ----------------------------------------------------------------------------------------------------------------- Bitmap Heap Scan on foo (cost=7.66..24.46 rows=453 width=32) (actual time=0.018..0.018 rows=1 loops=1) Recheck Cond: ("right"(x, 3) > 'fff'::text) Heap Blocks: exact=1 -> Bitmap Index Scan on foo_r3 (cost=0.00..7.55 rows=453 width=0) (actual time=0.010..0.010 rows=1 loops=1) Index Cond: ("right"(x, 3) > 'fff'::text) Planning Time: 0.072 ms Execution Time: 0.063 ms (7 rows)