Обсуждение: Regarding pg_dump utility

"soni de" <soni.de@gmail.com> writes:
> We have to take a backup of database and we know the pg_dump utility of
> postgresql.

> But may I know, is there any API for this pg_dump utility so that we can
> call it from the C program? Or only script support is possible for this.

There's always system(3) ....

            regards, tom lane

On Thu, Jun 08, 2006 at 11:39:48AM +0530, soni de wrote:
> We have to take a backup of database and we know the pg_dump utility of
> postgresql.
>
> But may I know, is there any API for this pg_dump utility so that we can
> call it from the C program? Or only script support is possible for this.

It probably wouldn't be terribly difficult to put the guts of pg_dump
into a library that you could interface with via C. I'm not sure if the
community would accept such a patch; though, I seem to recall other
people asking for this on occasion.

> I think script support is bit risky because if anything goes wrong while
> taking backup using pg_dump then user will not understand the problem of
> falling
>
> If only script support is possible then what should we prefer perl or shell?

Depends on what you're trying to accomplish. Perl is a much more capable
language than shell, obviously.
--
Jim C. Nasby, Sr. Engineering Consultant      jnasby@pervasive.com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461

Tom Lane wrote:
> "soni de" <soni.de@gmail.com> writes:
>> We have to take a backup of database and we know the pg_dump utility of
>> postgresql.
>
>> But may I know, is there any API for this pg_dump utility so that we can
>> call it from the C program? Or only script support is possible for this.
>
> There's always system(3) ....

fork(), exec()...

--
Until later, Geoffrey

Any society that would give up a little liberty to gain a little
security will deserve neither and lose both.  - Benjamin Franklin

Jim C. Nasby wrote:
> On Thu, Jun 08, 2006 at 11:39:48AM +0530, soni de wrote:
> > We have to take a backup of database and we know the pg_dump utility of
> > postgresql.
> >
> > But may I know, is there any API for this pg_dump utility so that we can
> > call it from the C program? Or only script support is possible for this.
>
> It probably wouldn't be terribly difficult to put the guts of pg_dump
> into a library that you could interface with via C. I'm not sure if the
> community would accept such a patch; though, I seem to recall other
> people asking for this on occasion.

Personally I think it would be neat.  For example the admin-tool guys
would be able to get a dump without invoking an external program.
Second it would really be independent of core releases (other than being
tied to the output format.)  pg_dump would be just a simple caller of
such a library, and anyone else would be able to get dumps easily, in
whatever format.

--
Alvaro Herrera                                http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support

Alvaro Herrera wrote:

>
>
> Personally I think it would be neat.  For example the admin-tool guys
> would be able to get a dump without invoking an external program.
> Second it would really be independent of core releases (other than being
> tied to the output format.)  pg_dump would be just a simple caller of
> such a library, and anyone else would be able to get dumps easily, in
> whatever format.

pgAdmin currently invokes pg_dump/restore externally with pipes attached
to stdin/out/err, but a library implementation would solve some
headaches (esp. concerning portability) managing background
execution/GUI updates/process control. I'd like a libpgdumprestore
library, with pg_dump/pg_restore being lean wrapper programs.

Regards,
Andreas

On Thu, Jun 08, 2006 at 06:33:28PM +0200, Andreas Pflug wrote:
> Alvaro Herrera wrote:
>
> >
> >
> >Personally I think it would be neat.  For example the admin-tool guys
> >would be able to get a dump without invoking an external program.
> >Second it would really be independent of core releases (other than being
> >tied to the output format.)  pg_dump would be just a simple caller of
> >such a library, and anyone else would be able to get dumps easily, in
> >whatever format.
>
> pgAdmin currently invokes pg_dump/restore externally with pipes attached
> to stdin/out/err, but a library implementation would solve some
> headaches (esp. concerning portability) managing background
> execution/GUI updates/process control. I'd like a libpgdumprestore
> library, with pg_dump/pg_restore being lean wrapper programs.

Would a pg_dumpall library also make sense?
--
Jim C. Nasby, Sr. Engineering Consultant      jnasby@pervasive.com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461

Jim C. Nasby wrote:
> On Thu, Jun 08, 2006 at 06:33:28PM +0200, Andreas Pflug wrote:
> > Alvaro Herrera wrote:
> >
> > >
> > >
> > >Personally I think it would be neat.  For example the admin-tool guys
> > >would be able to get a dump without invoking an external program.
> > >Second it would really be independent of core releases (other than being
> > >tied to the output format.)  pg_dump would be just a simple caller of
> > >such a library, and anyone else would be able to get dumps easily, in
> > >whatever format.
> >
> > pgAdmin currently invokes pg_dump/restore externally with pipes attached
> > to stdin/out/err, but a library implementation would solve some
> > headaches (esp. concerning portability) managing background
> > execution/GUI updates/process control. I'd like a libpgdumprestore
> > library, with pg_dump/pg_restore being lean wrapper programs.
>
> Would a pg_dumpall library also make sense?

One would think that libpgdump should take care of this as well ...

--
Alvaro Herrera                                http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support

> It probably wouldn't be terribly difficult to put the guts of pg_dump
> into a library that you could interface with via C. I'm not sure if the
> community would accept such a patch; though, I seem to recall other
> people asking for this on occasion.
>
>> I think script support is bit risky because if anything goes wrong while
>> taking backup using pg_dump then user will not understand the problem of
>> falling
>>
>> If only script support is possible then what should we prefer perl or shell?
>
> Depends on what you're trying to accomplish. Perl is a much more capable
> language than shell, obviously.


In phpPgAdmin we just execute pg_dump as a child process and capture its
output....

> Personally I think it would be neat.  For example the admin-tool guys
> would be able to get a dump without invoking an external program.
> Second it would really be independent of core releases (other than being
> tied to the output format.)  pg_dump would be just a simple caller of
> such a library, and anyone else would be able to get dumps easily, in
> whatever format.

What about fully completing our SQL API for dumping?

ie. We finish adding pg_get_blahdef() for all objects, add a function
that returns the proper ordering of all objects in the database, and
then somehow drop out a dump with a single JOIN :D

Chris