Message-ID: <3CA8C37F.4000607@petig-baender.de>
Date: Mon, 01 Apr 2002 22:30:55 +0200
From: Christof Petig <christof@petig-baender.de>
Organization: Adolf Petig GmbH & Co. KG
User-Agent: Mozilla/5.0 (X11; U; Linux ppc; en-US; rv:0.9.8) Gecko/20020309
MIME-Version: 1.0
To: Murphy Pope <pope_murphy@hotmail.com>
Cc: pgsql-interfaces@postgresql.org
Subject: Re: A dynamic SQL/ecpg question
References: <OE70kVx3OfSap7LhLNy0000ad00@hotmail.com>
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Transfer-Encoding: 7bit

Murphy Pope wrote:
> Can anyone explain the difference between the following descriptor members?
> 
>  
> 
> LENGTH
> 
> OCTET_LENGTH
> 
> RETURNED_LENGTH
> 
> RETURNED_OCTET_LENGTH
> 
>  
> 
>  From looking at the source code, the last two are identical and it 
> looks like they return the length of an individual row/column value 
> (i.e. for a varchar column, they would return the length of an actual 
> varchar value).
> 
>  
> 
> I think OCTET_LENGTH will return the size of the column as stored in the 
> database.
> 
>  
> 
> I can't quite figure out what LENGTH is supposed to do.  It returns 
> PQfmod( ) - VARHDRSZ.  How is that different from the OCTET_LENGTH?

The problem is with pgsql's frontend/backend protocol (libpq). You only 
get these two values, and I can't imagine a query which gives the 
requested values. So you can't get/set any sensible values for two of them.
  Christof