To: Teunis Peters <teunis@wintersgift.com>
Cc: pgsql-interfaces@postgresql.org
Subject: Re: Two seperate problems with libpq - arrays and bytea edit 
In-reply-to: <4dc6bdd876380e9a6d8673c5d36c449f@wintersgift.com> 
References: <4dc6bdd876380e9a6d8673c5d36c449f@wintersgift.com>
Comments: In-reply-to Teunis Peters <teunis@wintersgift.com>
	message dated "Sat, 14 May 2005 11:40:10 -0700"
Date: Sat, 14 May 2005 14:51:13 -0400
Message-ID: <5157.1116096673@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

Teunis Peters <teunis@wintersgift.com> writes:
> I'm trying to figure out how to read from and write to bytea values and 
> array (specifically "text[2][]" for a key:value 'dictionary') and 
> cannot figure it out.

Well, since you are asking for binary output format from PQexecParams,
the bytea result is going to just be raw binary data: you should not be
trying to apply PQunescapeBytea to it.  I don't know the notation you
are using well enough to tell what's wrong with your second variant.

> Arrays I'm completely lost - I haven't a clue what the format would be.

Looking at array_send, the binary wire format is

	number of dimensions (int4)
	flags (int4)
	element type id (Oid)
	for each dimension:
		dimension length (int4)
		dimension lower subscript bound (int4)
	for each array element:
		element value, in the appropriate format

The "flags" are currently always 0, and I would recommend punting if
you see something else, since something else would very possibly
indicate a change in the wire format.

Don't forget that the wire format for integers is network byte order
(ie, big-endian).

			regards, tom lane