hashlib

Overview

build-deps: python3-docutils

Version

Build

You can build the RPM / DEB packages for pg_hashlib using pig build:

pig build pkg pg_hashlib         # build RPM / DEB packages

Install

You can install pg_hashlib directly. First, make sure the PGDG and PIGSTY repositories are added and enabled:

pig repo add pgsql -u          # Add repo and update cache

Install the extension using pig or apt/yum/dnf:

• Install
• pig
• dnf
• apt

pig install pg_hashlib;          # Install for current active PG version

pig ext install -y pg_hashlib -v 18  # PG 18
pig ext install -y pg_hashlib -v 17  # PG 17
pig ext install -y pg_hashlib -v 16  # PG 16
pig ext install -y pg_hashlib -v 15  # PG 15
pig ext install -y pg_hashlib -v 14  # PG 14

dnf install -y pg_hashlib_18       # PG 18
dnf install -y pg_hashlib_17       # PG 17
dnf install -y pg_hashlib_16       # PG 16
dnf install -y pg_hashlib_15       # PG 15
dnf install -y pg_hashlib_14       # PG 14

apt install -y postgresql-18-pg-hashlib   # PG 18
apt install -y postgresql-17-pg-hashlib   # PG 17
apt install -y postgresql-16-pg-hashlib   # PG 16
apt install -y postgresql-15-pg-hashlib   # PG 15
apt install -y postgresql-14-pg-hashlib   # PG 14

Create Extension:

CREATE EXTENSION hashlib;

Usage

hashlib: Stable hash functions library for PostgreSQL

Provides stable hash functions whose implementations do not change across PostgreSQL versions.

String Hashing (32-bit)

SELECT hash_string('hello', 'crc32');
SELECT hash_string('hello', 'murmur3');

With optional initial value:

SELECT hash_string('hello', 'crc32', 42);

String Hashing (64-bit)

SELECT hash64_string('hello', 'city64');
SELECT hash64_string('hello', 'siphash24');
SELECT hash64_string('hello', 'lookup3');

String Hashing (128-bit)

SELECT hash128_string('hello', 'md5');
SELECT hash128_string('hello', 'city128');
SELECT hash128_string('hello', 'spooky');

Integer Hashing

SELECT hash_int4(42);        -- 32-bit hash of 32-bit integer
SELECT hash_int8(42::bigint); -- 64-bit hash of 64-bit integer

Available Algorithms

Integer algorithms: wang32, wang32mult, jenkins (32-bit); wang64, wang64to32 (64-bit). All are reversible (1:1 mapping), useful for creating random sort orders over unique IDs.