This is a list of useful PostgreSQL extensions.

PgBouncer: Worker pool for PostgreSQL connections, basically used to reduce memory usage. You will want to use this in production, limit the database connections to around 20 and allow around 1000 connections to the bouncer.

uuid-ossp: Generate universally unique identifiers (UUID) for primary keys. The probability of identical identifiers is non-existent.

PostGIS: Adds support for geographical objects to PostgreSQL.

Find the closes N items to location X.

pgSphere: Adds support to handle spherical coordinates and objects.

Calculating astronomical data.

PostPic: Adds support for storing images and doing image processing.

crop, resize, rotate, get height, get width

Texcaller: Adds support for TeX command line tools.

Converting TeX file to PDF.

pgmemcache: Adds support for memcached.

Write, read, search or delete data from memcached.

prefix: Adds support for searching text prefixes with @> operand.

Multicorn: Adds support for fetching data from other databases.

Data from MySQL database, CSVs or RSS feeds.

intarray: Adds support for functions for NULL-free arrays of integers.

sort(), icount(), uniq()
int[] && int[] => TRUE if contain at least one common integer

PL/Proxy: Adds support to partitioning your database.

repmgr: Set of tools to help manage PostgreSQL database clusters.

Sources

• Costs of a PostgreSQL connection