| From: | Merlin Moncure <mmoncure(at)gmail(dot)com> |
|---|---|
| To: | Albe Laurenz <laurenz(dot)albe(at)wien(dot)gv(dot)at> |
| Cc: | "fanlijing *EXTERN*" <fanlijing(at)cn(dot)fujitsu(dot)com>, pgsql-admin(at)postgresql(dot)org, pgsql-general(at)postgresql(dot)org |
| Subject: | Re: [GENERAL] how to save a bytea value into a file? |
| Date: | 2011-10-10 15:51:14 |
| Message-ID: | CAHyXU0y06Q-ujZG+jcvbOuycdv1x9MgeDxfmnWSmqfYK0Bu0uw@mail.gmail.com |
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| Lists: | pgsql-admin pgsql-general |
On Mon, Oct 10, 2011 at 9:26 AM, Albe Laurenz <laurenz(dot)albe(at)wien(dot)gv(dot)at> wrote:
> I wrote:
> [fanlijing wants to write bytea to file]
>> A simple
>> COPY (SELECT byteacol WROM mytab WHERE ...) TO 'filename' (FORMAT
> binary)
>> should do the trick.
>
> Corrections:
> a) "binary" must be surrounded by single quotes.
> b) that won't dump just the binary data - you would have
> to remove the first 25 bytes and the last 2 bytes...
>
> So maybe using the functions I mentioned would be the
> best way after all.
>
> You could also write your own user defined function in C.
A user defined function, or a binary wire format speaking client side
extractor in C/libpq. The basic rule of thumb for me regarding C
inside the server is 'only when no other reasonable solution exists'.
merlin
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