7.2b3 pg_dump, general 7.2b3 comments

Joe Conway <joseph.conway@home.com> writes:

Is pg_dump supposed to work against prior version databases?

Since 7.1.1 we've tried to make it do so.

# pg_dump -h 172.16.1.84 -U postgres -t el_names -i lt_lcat > el_names.dmp
Password: <types in password>
pg_dump: query to obtain list of tables failed: ERROR: Attribute
'relhasoids' not found

<scratches head> Odd. There's only one query in pg_dump that touches
relhasoids, and it's set up to only be used when "remoteVersion >= 70200".
It seems to work here, too: I can dump from a 7.1 or even 7.0 server
with current pg_dump. Would you burrow in there and see what's screwing
up the version-check code?

BTW, what happens if you leave off -i? It shouldn't be necessary.

regards, tom lane

Joe Conway <joseph.conway@home.com> writes:

Is pg_dump supposed to work against prior version databases? I was
moving data from an old server (running 7.2devel from several months

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

ago) to a new server (running 7.2b3), using pg_dump on the *new* server,
and got the following message:

# pg_dump -h 172.16.1.84 -U postgres -t el_names -i lt_lcat > el_names.dmp
Password: <types in password>
pg_dump: query to obtain list of tables failed: ERROR: Attribute
'relhasoids' not found

Oh, never mind: I see it. pg_dump's test is on whether the server calls
itself 7.2 or not. You've evidently got a copy from back before the
changes to make OIDs optional. The versioning code is not set up to
deal with intermediate development versions, so it gets it wrong about
what query to use. You'll need to use the pg_dump of the same vintage
as the 7.2devel server.

You're a brave man to be putting production data on CVS-tip servers.
I wouldn't recommend it ;-)

regards, tom lane

Tom Lane wrote:

Joe Conway <joseph.conway@home.com> writes:

Is pg_dump supposed to work against prior version databases? I was
moving data from an old server (running 7.2devel from several months

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

ago) to a new server (running 7.2b3), using pg_dump on the *new* server,
and got the following message:

# pg_dump -h 172.16.1.84 -U postgres -t el_names -i lt_lcat > el_names.dmp
Password: <types in password>
pg_dump: query to obtain list of tables failed: ERROR: Attribute
'relhasoids' not found

Oh, never mind: I see it. pg_dump's test is on whether the server calls
itself 7.2 or not. You've evidently got a copy from back before the
changes to make OIDs optional. The versioning code is not set up to
deal with intermediate development versions, so it gets it wrong about
what query to use. You'll need to use the pg_dump of the same vintage
as the 7.2devel server.

You're a brave man to be putting production data on CVS-tip servers.
I wouldn't recommend it ;-)

regards, tom lane

Thanks, but I'm not that brave. This has been my proof-of-concept server
for the past 6 or so months. The new server is intended to become a
production, relatively high volume data collection server on our factory
floor. I've finally been successful at selling our upper management on
using PostgreSQL in lieu of commercial databases for this purpose (we
already have multiple instances of brand O and brand M). In fact, given
the current economy, they're enthusiastic about it ;-)

In any case, I've already moved the data, just wanted to report the
possible issue. It sounds like it shouldn't affect any but the highly
adventurous!

BTW, after your first reply, I started to load the new pg_dump into gdb
and discovered it had no debug symbols (recall I installed from RPM). Is
there a way to install the RPM with additional configure options without
rebuilding it? Is there any significant downside (performance or
otherwise) to having --enable-debug on a production server?

-- Joe

Joe Conway <joseph.conway@home.com> writes:

BTW, after your first reply, I started to load the new pg_dump into gdb
and discovered it had no debug symbols (recall I installed from RPM). Is
there a way to install the RPM with additional configure options without
rebuilding it?

Don't know; certainly you'd have to recompile, but I dunno if you have
to modify the source RPM or not. Lamar?

Is there any significant downside (performance or
otherwise) to having --enable-debug on a production server?

If you're compiling with gcc then I believe the only cost is the disk
footprint of the debug info. On some other compilers, --enable-debug
disables most compiler optimizations, which can mean a significant
speed penalty. We currently have the following in the installation
guide:

--enable-debug

Compiles all programs and libraries with debugging
symbols. This means that you can run the programs through a
debugger to analyze problems. This enlarges the size of the
installed executables considerably, and on non-GCC compilers it
usually also disables compiler optimization, causing
slowdowns. However, having the symbols available is extremely
helpful for dealing with any problems that may
arise. Currently, this option is considered of marginal value
for production installations, but you should have it on if you
are doing development work or running a beta version.

--enable-cassert

Enables assertion checks in the server, which test for many
"can't happen" conditions. This is invaluable for code
development purposes, but the tests slow things down a
little. Also, having the tests turned on won't necessarily
enhance the stability of your server! The assertion checks are
not categorized for severity, and so what might be a relatively
harmless bug will still lead to server restarts if it triggers
an assertion failure. Currently, this option is not
recommended for production use, but you should have it on for
development work or when running a beta version.

Perhaps "marginal value" is too lukewarm an assessment, at least for
gcc users. Comments?

regards, tom lane

Tom Lane wrote:

Perhaps "marginal value" is too lukewarm an assessment, at least for
gcc users. Comments?

Well, if I have problems on my production machine, and I post a question
here, the first thing I'll be asked for is a backtrace, preferably with
symbols, right ;-)

So ISTM, that if there is no penalty except (a relatively trivial amount
of) disk space with gcc, then that ought to be the preferred
configuration for gcc. The "value" for a production installation is
significant if it helps get a problem fixed faster.

-- Joe

On Thursday 29 November 2001 01:27 am, Tom Lane wrote:

Joe Conway <joseph.conway@home.com> writes:

BTW, after your first reply, I started to load the new pg_dump into gdb
and discovered it had no debug symbols (recall I installed from RPM). Is
there a way to install the RPM with additional configure options without
rebuilding it?

Don't know; certainly you'd have to recompile, but I dunno if you have
to modify the source RPM or not. Lamar?

Hmmm. You know, it would be a good idea, IMHO, to enable debugging symbols in
the beta RPMs anyway. So, I will do that for the next beta (or release
candidate -- although, with that report from Jan, I wonder what the next
release will be).

In the meantime, Joe, if you can rebuild the RPM from source, here's what to
do:
1.) rpm -i the source RPM.
2.) If you've never built from a source RPM before, see
/usr/share/docs/postgresql-7.2b3/README.rpm-dist for some more information.
3.) Edit the spec file (on Red Hat, that would be in /usr/src/redhat/SPECS,
name of 'postgresql.spec'), adding the following line near the top:
%define __os_install_post /usr/lib/rpm/brp-compress
4.) Add the configure option. The rpm build process by default runs strip on
the binaries.....
5.) rpm -ba postgresql.spec, wait a few minutes for the build, and pick up
your RPMs in /usr/src/redhat/RPMS/i386.

Or you can just wait until I upload a set with that line in it..... :-)

--
Lamar Owen
WGCR Internet Radio
1 Peter 4:11

On Thursday 29 November 2001 07:59 pm, Lamar Owen wrote:

Or you can just wait until I upload a set with that line in it..... :-)

Said set is now being uploaded to ftp.postgresql.org. Look for the 0.3PGDG
sbinary et in /pub/binary/beta/RPMS/redhat-7.2, and the source in
......./SRPMS

My my, --enable-debug and disabling stripping in the build sure does inflate
the package size :-O

For reference: The entire binary set for 7.2b3-0.2PGDG weighs in at 7,036KB.
The debug-enabled 7.2b3-0.3PGDG set weighs in at 11,240KB. The biggest
increase is in the postgresql-contrib package, which increases from 1,192KB
to 2,940KB.

This build also has --enable-cassert.
--
Lamar Owen
WGCR Internet Radio
1 Peter 4:11

Lamar Owen wrote:

Hmmm. You know, it would be a good idea, IMHO, to enable debugging symbols in
the beta RPMs anyway. So, I will do that for the next beta (or release
candidate -- although, with that report from Jan, I wonder what the next
release will be).

In the meantime, Joe, if you can rebuild the RPM from source, here's what to
do:
1.) rpm -i the source RPM.
2.) If you've never built from a source RPM before, see
/usr/share/docs/postgresql-7.2b3/README.rpm-dist for some more information.
3.) Edit the spec file (on Red Hat, that would be in /usr/src/redhat/SPECS,
name of 'postgresql.spec'), adding the following line near the top:
%define __os_install_post /usr/lib/rpm/brp-compress
4.) Add the configure option. The rpm build process by default runs strip on
the binaries.....
5.) rpm -ba postgresql.spec, wait a few minutes for the build, and pick up
your RPMs in /usr/src/redhat/RPMS/i386.

Or you can just wait until I upload a set with that line in it..... :-)

Thanks for the instructions, Lamar -- that helps quite a bit. I'll give
this a try next week.

Joe

On Friday 30 November 2001 08:50 pm, Joe Conway wrote:

Lamar Owen wrote:

Or you can just wait until I upload a set with that line in it..... :-)

Thanks for the instructions, Lamar -- that helps quite a bit. I'll give
this a try next week.

While you're certainly welcome to do the work yourself, you are also equally
welcome to download the latest RPMset, which has debugging symbols enabled,
AFAIK.
--
Lamar Owen
WGCR Internet Radio
1 Peter 4:11

Lamar Owen wrote:

Lamar Owen wrote:

While you're certainly welcome to do the work yourself, you are also equally
welcome to download the latest RPMset, which has debugging symbols enabled,
AFAIK.

Thanks, I saw that, but I'd like to know how to do these kinds of
adjustments to RPMs anyway. I normally prefer to install from source
tarballs, or even CVS, but for production servers our network admins get
a warm fuzzy from RPMs. It gives them more confidence they can reproduce
the server setup if they need to after I hit the Lotto and retire ;-)

Joe