Thomas Hallgren wrote:
> Peter Eisentraut wrote:
>> Am Sonntag, 28. November 2004 12:33 schrieb Thomas Hallgren:
>>
>>> Hmm, ok. But there's no way to stream them in and out from disk. From
>>> what I can see, you have to bring all of it into memory. Not so ideal
>>> perhaps if you want to provide streaming media for thousands of users.
>>
>> You can use the substring function to read the pieces you need.
>>
> Won't the substring function bring the whole thing into memory in the
> backend before it pass you the piece you need? Let's assume I want to
> stream 4k at a time of a 40mb image, that's a whole lot of byte swapping
> if that's the case.
Not if the column is storage type EXTERNAL. See a past discussion here:
http://archives.postgresql.org/pgsql-general/2003-07/msg01447.php
> How do you handle writes without first creating the whole image in memory?
You can't currently, but it would be a nice addition ;-)
I agree with Peter -- I think effort is better spent improving bytea.
BTW, someone on GENERAL just started a very similar thread
("implementing a lo_truncate operation, and possibly a lo_size"). I've
cc'd him here.
Joe
