Re: Does Postgres compress data?

On 05/23/2012 06:07 PM, Mike Christensen wrote:
> If I run this query:
>
> select sum(length(html)) from Indexer.Pages;
>
> I get:
>
> 15,680,005,116
>
> However, if I type:
>
> C:\Program Files\PostgreSQL>dir /s
>
> I get:
>
> Total Files Listed:
> 5528 File(s) 7,414,385,333 bytes
> 575 Dir(s) 43,146,137,600 bytes free
>
> So all the Postgres data on disk is a little over 7 gigs, however the
> total sum of bytes in the HTML column of the Pages table is over 15
> gigs.
>
> Is PG compressing this data? I'm curious as I was considering
> converting this column to a byte array and gzip'ing the data to save
> space, however if PG is already doing this for me, then I'm not going
> to bother. Thanks!

Yes. See here for complete answer:

http://www.postgresql.org/docs/9.1/static/storage-toast.html

>
> Mike
>

--
Adrian Klaver
adrian(dot)klaver(at)gmail(dot)com