Re: Why does my DB size differ between Production and DR? (Postgres 8.4)

On Mon, Jan 31, 2011 at 7:52 PM, Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com> wrote:
> On Mon, Jan 31, 2011 at 5:54 PM, Aleksey Tsalolikhin
> <atsaloli(dot)tech(at)gmail(dot)com> wrote:
>> Situation:  Disk usage on production server root filesystem is at 68%
>> utilization (80 GB used), on DR is at 51% (56 GB used).   We use
>> SlonyII-1.2.x to keep the DR up to date.  I would like to account for
>> the 24 GB difference.
>
> This is likely free space in your database.  Some of it is completely
> normal and actually improves performance.  Too much and your db is
> bloated and things starting taking too long.

Thanks, Scott!

Bucardo's "check_postgres.pl --action bloat" complains about one table,
1 GB wasted. So the other tables must be OK.

So what about my DR, which doesn't have this same 20+ GB of "free space".
Will it acquire it once it goes into production? Will performance be impacted
as it acquires the free space? Should I even be concerned about the
difference in disk usage or is it normal and expected?

How do I find out how much actual data I have in my database, minus the
"free space"? Is there some built-in way to report this, or do I need to run
"SELECT * FROM *" and look at the byte count of the output?

Thanks,
-at