Database configuration
FreshRSS supports the databases SQLite (built-in), PostgreSQL, MySQL / MariaDB.
While the default installation should be fine for most cases, additional tuning can be made.
Full-text search optimisation in PostgreSQL
Without changing anything in FreshRSS’ code (which is using ILIKE), it is possible to make text searches much faster by adding some indexes in PostgreSQL 9.1+ (at the cost of more disc space and slower insertions):
CREATE EXTENSION pg_trgm;
CREATE INDEX gin_trgm_index_title ON freshrss_entry USING gin(title gin_trgm_ops);
CREATE INDEX gin_trgm_index_content ON freshrss_entry USING gin(content gin_trgm_ops);
Where freshrss_entry needs to be adapted to the name of the entry of a given use, e.g., freshrss_alice_entry.
Such an index on the entry.title column makes searches such as intitle:Hello much faster.
General searches such as Something search both on entry.title and entry.content and therefore require the two indexes shown above.
Likewise, if you wanted to speed up searches on the authors (author:Alice), you would add another index:
CREATE INDEX gin_trgm_index_author ON freshrss_entry USING gin(author gin_trgm_ops);
Etc. for other text fields. The list of fields can be seen in CREATE TABLE _entry section.