pgflate

Introduction

pgflate is a PostgreSQL extension that provides functions for deflating and inflating raw DEFLATE streams, with support for custom dictionaries.

Prerequisites

• PostgreSQL headers, libraries and PGXS build infrastructure
• pg_config must be in your PATH
• zlib

Building

Run make to build the extension.

Installation

Run make install as root (e.g. with sudo) to install the extension.

Debian package

The repository also contains the files for building a Debian package, which can be done by running pg_buildext updatecontrol followed by dpkg-buildpackage. I distribute pre-built versions for stable amd64 Debian using the apt.postgresql.org repository in my personal APT repository. Run apt-get install postgresql-PGVERSION-flate as root after setting up the repository.

Usage

Run CREATE EXTENSION flate to install the extension in the current database. Two functions are provided:

Function	Return Type
deflate(data bytea [, dictionary bytea [, level integer ]])	bytea
inflate(data bytea [, dictionary bytea ])	bytea

deflate compresses the provided data and returns a raw DEFLATE stream. A preset dictionary may also be provided. The default compression level may also be overriden, valid values range from 0 (no compression), 1 (best speed) to 9 (best compression).

If you want to override the compression level without using a dictionary, set dictionary to NULL.

inflate decompresses the provided DEFLATE stream in data and returns the uncompressed data. A preset dictionary, matching the dictionary used to deflate the data, may also be provided.

Example

gpe=# CREATE EXTENSION flate;
CREATE EXTENSION
gpe=# SELECT deflate('hello hello hello hello', 'hello', 9);
     deflate
------------------
 \xcb00110a182400
(1 row)

gpe=# SELECT convert_from(inflate('\xcb00110a182400', 'hello'), 'utf-8');
      convert_from
-------------------------
 hello hello hello hello
(1 row)

gpe=#

License

This project is available under the terms of the ISC license, which is similar to the 2-clause BSD license. See the LICENSE file for the copyright information and licensing terms.