_ilike

ilike search by resource content

With _ilike search parameter you search for terms inclusion as substring in text representation of FHIR resource. Interesting feature of this parameter, that it can provide quick feedback to user about matches without forcing to print the whole word (as with full text search). For example jo will find Johns and Jolie or asp will match Aspirin.

GET /Patient?_ilike=joh+smit,jes+park

With _ilike parameter you term separated with space combined with AND and separated by comma , with OR. Example above is translated into SQL query like this:

SELECT * FROM patient
WHERE
resource::text ilike '%joh%' AND ... ilike '%smit%'
OR
resource::text ilike '%jes%' AND ... '%park%'

ILIKE search can be efficiently indexed with trigram PostgreSQL extension and GIN Index, providing response in tens of miliseconds responses on milions of records.

CREATE INDEX patient_trgm_idx  on patient
USING gin (
  (id || ' ' || resource::text) gin_trgm_ops
);

VACUUM ANALYZE patient;