doc: add PostgreSQL extensions setup and usage details

server/README.md

@@ -11,3 +11,28 @@ yarn workspace @zerologementvacant/server knex seed:make \
 
 Knex will create a seed file in `src/infra/database/seeds` with the name
 `<timestamp>_<name>.ts`.
+
+## Required PostgreSQL Extensions
+
+This project relies on the following PostgreSQL extensions to enhance database functionality:
+
+- **uuid-ossp**: Enables the generation of universally unique identifiers (UUIDs), useful for creating unique keys across distributed systems.
+- **postgis**: Adds spatial database capabilities for managing and querying geographic data, enabling advanced geospatial queries (owners and housings).
+- **unaccent**: Provides functionality to remove accents from strings, improving search flexibility. To ensure efficient usage with indexed text searches, define an immutable wrapper function:
+
+```sql
+CREATE OR REPLACE FUNCTION immutable_unaccent(text)
+RETURNS text AS $$
+SELECT unaccent($1)
+$$ LANGUAGE sql IMMUTABLE STRICT;
+```
+
+- **pg_trgm**: Supports similarity and trigram-based text searches. It is particularly effective for fuzzy string matching and partial text search. To optimize full-text searches, create an index using:
+
+```sql
+CREATE INDEX IF NOT EXISTS owners_full_name_trgm_idx
+ON owners
+USING GIN (immutable_unaccent(full_name) gin_trgm_ops);
+```
+
+Ensure these extensions are installed and activated in your PostgreSQL database using CREATE EXTENSION IF NOT EXISTS extension_name;.