Re: why is pg_dump so much smaller than my database?

On 29 March 2012 09:11, John R Pierce <pierce(at)hogranch(dot)com> wrote:
> On 03/28/12 10:32 PM, Carson Gross wrote:
>>
>> I've got a pretty big database (~30 gigs) and when I do a pg_dump, it ends
>> up only being 2 gigs.

I suppose you're talking about a plain text dump here? A compressed
dump would likely[*] be quite a bit smaller than your database.

And as John already says, deleted tuples do not get dumped, neither do
index contents. Any fill-factors defined on tables or indexes would
also account for a difference in size.

*: This does depend on what data you store, of course. A database that
mainly consists of stored JPEG images, for example, wouldn't compress
much. A database with the same text data over and over would compress
immensely.
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