Re: Why Size Of Data Backed Up Varies Significantly In SQL 6.5?

Peter Eisentraut <peter_e@gmx.net> writes:
> Wendy writes:
>> I backed up a database at night and noted the size to be about over 300MB.
>> The following morning, I again backed up the same database and found out the
>> size to be less than 100MB. There was no massive deletes by users during
>> that morning.
>> What would account to that vast difference in size?

> If you have done a VACUUM in between it's possible that a lot of dead rows
> were deleted.

But what sort of backup is Wendy talking about?  If she's reporting the
size of pg_dump's output file then I'd be just as worried as she is.
If she's talking about a tar of the $PGDATA directory then the VACUUM
explanation holds water (and she's wasting her time making such dumps).

            regards, tom lane