How to download Postgres bytea column as file

Question

Currently, i have a number of files stored in postgres 8.4 as bytea. The file types are .doc, .odt, .pdf, .txt and etc.

May i know how to download all the file store

Answer 1

One simple option is to use COPY command with encode to hex format and then apply xxd shell command (with -p continuous hexdump style switch). For example let's say I have jpg image in bytea column in samples table:

\copy (SELECT encode(file, 'hex') FROM samples LIMIT 1) TO
    '/home/grzegorz/Desktop/image.hex'

$ xxd -p -r image.hex > image.jpg

As I checked it works in practice.