Обсуждение: size of pg_dump files containing bytea values

I notice that non-printables in bytea values are being spit out by pg_dump
using escaped octet sequences even when the "-Fc" option is present
specifying use of the custom binary output format rather than plain text
format.  This bloats the size of bytea values in the dump file by a factor
of 3+ typically.  When you have alot of large bytea values in your db this
can add up very quickly.

Shouldn't the custom format be smart and just write the raw bytes to the
output file rather than trying to make them ascii readable?

Thanks.

Steve McWilliams
Software Engineer
Emprisa Networks
703-691-0433x21
smcwilliams@emprisanetworks.com

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"Steve McWilliams" <smcwilliams@EmprisaNetworks.com> writes:
> I notice that non-printables in bytea values are being spit out by pg_dump
> using escaped octet sequences even when the "-Fc" option is present
> specifying use of the custom binary output format rather than plain text
> format.  This bloats the size of bytea values in the dump file by a factor
> of 3+ typically.

No, because the subsequent compression step should buy back most of
that.

            regards, tom lane

Tom Lane <tgl@sss.pgh.pa.us> writes:

> "Steve McWilliams" <smcwilliams@EmprisaNetworks.com> writes:
> > I notice that non-printables in bytea values are being spit out by pg_dump
> > using escaped octet sequences even when the "-Fc" option is present
> > specifying use of the custom binary output format rather than plain text
> > format.  This bloats the size of bytea values in the dump file by a factor
> > of 3+ typically.
>
> No, because the subsequent compression step should buy back most of
> that.

Didn't byteas used to get printed as hex? Even in psql they're now being
printed in the escaped octet sequence. When did this change?

--
greg

Greg Stark <gsstark@mit.edu> writes:
> Didn't byteas used to get printed as hex?

No, not that I recall.  I don't have anything older than 7.0 running,
but it behaves the same as now:

play=> select 'xyz\\001'::bytea;
 ?column?
----------
 xyz\001
(1 row)

play=>

            regards, tom lane

* Greg Stark:

> Didn't byteas used to get printed as hex?

No, they didn't.  It would be useful to support hexadecimal BYTEA
literals, though.  Unfortunately, X'DEADBEEF' has already been taken
by bit strings.

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