Thread: Need some info.

Need some info.

From
"Suresh Gupta VG"
Date:

Hi Team,

 

We are upgrading the pgsql from 7.4.2 to 8.2.5 on Solaris 9 Spark machine, I had downloaded the sources also. I had gone through the instalation documents too. I could not find the procedure to rollback the new version, if the new version does not support our application.

Queries :-

1)       Can we do rollback if required after complete installation??

2)       Pls provide the link or related docs if any. Else is there any alternative way to get back to old version after complete installation?

3)       If we do the installation in the other directory which doesn’t contain old version. Does it solve our problem

 

Pls advice on this.

Regards,

G. V. Suresh Gupta

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Re: Need some info.

From
Andrew Sullivan
Date:
On Thu, Jan 10, 2008 at 01:07:09PM +0530, Suresh Gupta VG wrote:
> We are upgrading the pgsql from 7.4.2 to 8.2.5 on Solaris 9 Spark
> machine, I had downloaded the sources also. I had gone through the
> instalation documents too. I could not find the procedure to rollback
> the new version, if the new version does not support our application.

This is a difficulty, yes.

> 1)       Can we do rollback if required after complete installation??

Generally, major releases are binary incompatible.  If you find your upgrade
fails, you can of course continue to use your old installation (so don't
delete your old data directory!).  But if you've processed transactions in
the new system, they'll be lost to the old installation, and then you're
hosed.

What you _can_ do, however, is install Slony.  You might need to upgrade
your 7.4 version to do this -- the version you have is very old, and there
are some bugs that might affect Slony (I don't remember).  Not to worry --
that shouldn't be a big deal (it's not a dump and restore).  But it will
require some planning and such.  What you do, in this case, is install Slony
on 7.4, add the 8.2.x replica, and let it catch up.  When it's time to do
your upgrade, you do a switchover (not a failover) and cause the 8.2.x to
replicate to your 7.4.x installation.  Now transactions that happen in 8.2
will also appear in 7.4, and if something blows up, you can switch back.

This feature is an explicit design goal of Slony, and Afilias has used it in
production, so I can be confident it works.  But you need to do a lot of
planning and testing.  It isn't something to do in a couple days' time.

> 3)       If we do the installation in the other directory which doesn't
> contain old version. Does it solve our problem

Sort of; see above.

A



Re: Need some info.

From
"Vishal Mailinglist"
Date:
Hi ,

Before you do any thing like upgrade backup is the mantra
  • in plain sql format
  • File system base ( remember to shutdown postgresql before taking backup)
  • pg_dump

Queries :-

1)       Can we do rollback if required after complete installation??


Yes you would be able to, make sure you overwrite all binaries of old PostgreSQL when upgrade , in case of rollback simply compile and overwrite binary.

3)       If we do the installation in the other directory which doesn't contain old version. Does it solve our problem


Yes that may help this way you may not have to do the file system backup.


--
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Vishal Kashyap.
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