Thread: how do i store \0 inside a text attribute?

for my pgcat utility i now know i have to use \nnn octal quoting for
nonprintables in the generated INSERT commands.  but in testing, i
found the following oddity.  this is in 7.1-b1 (cvs-current).
vixie=> create table foo ( bar text );CREATEvixie=> insert into foo values ( 'a\033b' );INSERT 728084 1vixie=> select
length(bar)from foo;length------     3(1 row)
 

great!  it stored the escape.  and since SELECT's front/back end protocol
is counted-string rather than quoted text, it comes back reliably (though
i still intend to try a binary cursor at some point, just to do it.)  BUT:
vixie=> delete from foo;DELETE 1vixie=> insert into foo values ( 'a\0b' );INSERT 728085 1vixie=> select length(bar)
fromfoo;length------     1(1 row)
 
vixie=> drop table foo;DROPvixie=> \q

this is not what i was hoping for at ALL.  evidently the implementation of
text assumes NUL-termination in other places than the parser.  ultimately
this means that pgsql will need a "blob" type whose presentation format is
uuencode or some such.  but is there a workaround for this using "text"?

how would someone be expected to store, say, a GIF image in a TOAST text?

Paul A Vixie <vixie@mfnx.net> writes:
> this is not what i was hoping for at ALL.  evidently the implementation of
> text assumes NUL-termination in other places than the parser.

Yes.  The entire datatype I/O system is based on null-terminated
strings, so there's no easy way to fix this.  If it were just an
internal problem then maybe we'd bite the bullet and do it, but
breaking every user-defined datatype in existence seems too high
a price to pay for this problem.

> ultimately
> this means that pgsql will need a "blob" type whose presentation format is
> uuencode or some such.

See bytea, though its presentation format leaves something to be desired
IMHO.

> how would someone be expected to store, say, a GIF image in a TOAST text?

One would not.  A TOASTed bytea is the appropriate column type.
        regards, tom lane

> See bytea, though its presentation format leaves something to be desired IMHO
> 
> > how would someone be expected to store, say, a GIF image in a TOAST text?
> 
> One would not.  A TOASTed bytea is the appropriate column type.

thanks -- that's EXACTLY what i needed.

> > See bytea, though its presentation format leaves something to be desired IMHO
> > 
> > > how would someone be expected to store, say, a GIF image in a TOAST text?
> > 
> > One would not.  A TOASTed bytea is the appropriate column type.
> 
> thanks -- that's EXACTLY what i needed.
> 

bytea was not really used very much until people started asking to do
this kind of think.

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
853-3000+  If your life is a hard drive,     |  830 Blythe Avenue +  Christ can be your backup.        |  Drexel Hill,
Pennsylvania19026