Обсуждение: RHEL OS upgrade from 6.7 (Current version) to 8 version for Postgresql database

Dear Team,

 

we are planing to RHEL OS upgrade from 6.7 (Current version)  to 8 version.

currently postgresql-12.6 version running on the server ,  we have upgraded OS on test DB server from 6 to 8 version  during  OS upgrade postgresql-12,11 and other package is removed  and Postgresql is not started. that why my DB is crashed , can you please suggest what is best way to upgrade OS.

-- 
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ram pratap maurya <rampratap0000@gmail.com> writes:
> we are planing to RHEL OS upgrade from 6.7 (Current version)  to 8 version.

> currently postgresql-12.6 version running on the server ,  we have upgraded
> OS on test DB server from 6 to 8 version  during  OS upgrade
> postgresql-12,11 and other package is removed  and Postgresql is not
> started. that why my DB is crashed , can you please suggest what is best
> way to upgrade OS.

There are a couple of big gotchas you need to think about:

* RHEL8 is systemd based, while 6 still used the old initscript startup
code.  This means that the way to get a daemon process launched is
completely different.  So PG packages built for RHEL6 *will not work*.
You need to get a server package that is systemd-ready, and that means
one that was explicitly built for RHEL8.  (Maybe a RHEL7 one would
work, not sure.  But it is zero surprise that the packages you listed
aren't working.)

* RHEL8 incorporates new locale data [1].  This means that non-English
text is rather likely to sort differently than it did before, which in
turn means that indexes on text columns will be corrupt if you try to
upgrade in place.  While you could REINDEX them after updating, this
might be a good reason to do a dump-and-reload instead of trying to
pg_upgrade.

In short, this is no minor upgrade you're contemplating.

            regards, tom lane

[1] https://wiki.postgresql.org/wiki/Locale_data_changes

> On Mar 19, 2021, at 8:19 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> RHEL8 incorporates new locale data [1].  This means that non-English
> text is rather likely to sort differently than it did before

I *think* I saw that random uuid-style strings of alphanumerics and underscores or dashes also sorted differently. I
didn'tstop to take time to definitively verify that, but just kept on with re-indexing as quickly as possible. But I
definitelysaw symptoms of corrupted indexes until the reindex completed, and they appeared with the OS upgrade, not
before,*as far as I know* 

On a side note, shouldn't you be upgrading to CentOS Stream instead of 
CentOS 8?

Tom Lane wrote on 3/19/2021 10:19 AM:
> ram pratap maurya <rampratap0000@gmail.com> writes:
>> we are planing to RHEL OS upgrade from 6.7 (Current version)  to 8 version.
>> currently postgresql-12.6 version running on the server ,  we have upgraded
>> OS on test DB server from 6 to 8 version  during  OS upgrade
>> postgresql-12,11 and other package is removed  and Postgresql is not
>> started. that why my DB is crashed , can you please suggest what is best
>> way to upgrade OS.
> There are a couple of big gotchas you need to think about:
>
> * RHEL8 is systemd based, while 6 still used the old initscript startup
> code.  This means that the way to get a daemon process launched is
> completely different.  So PG packages built for RHEL6 *will not work*.
> You need to get a server package that is systemd-ready, and that means
> one that was explicitly built for RHEL8.  (Maybe a RHEL7 one would
> work, not sure.  But it is zero surprise that the packages you listed
> aren't working.)
>
> * RHEL8 incorporates new locale data [1].  This means that non-English
> text is rather likely to sort differently than it did before, which in
> turn means that indexes on text columns will be corrupt if you try to
> upgrade in place.  While you could REINDEX them after updating, this
> might be a good reason to do a dump-and-reload instead of trying to
> pg_upgrade.
>
> In short, this is no minor upgrade you're contemplating.
>
>             regards, tom lane
>
> [1] https://wiki.postgresql.org/wiki/Locale_data_changes
>
>

This is the first I have heard about Centos Stream. I found an announcement dated 8 December 2020 saying that CentOS
Projectis shifting focus to CentOS Stream, and a LOT of comments and confusion. 
The main thing is that Stream apparently tracks Ahead of a current RHEL release.
This may be a concern because I and many others use CentOS as a stable 'tried and tested' platform not a 'cutting edge'
platform.

Of course, I may be just as confused as everyone else seems to be about what all this actually means.

Getting a bit off topic here, so apologies if I'm upsetting anyone.

Regards,
Dave Bolt

-----Original Message (extract) -----
From: MichaelDBA [mailto:MichaelDBA@sqlexec.com]
Sent: 19 March 2021 17:18
To: Tom Lane
Cc: ram pratap maurya; paul.foerster@gmail.com; pgsql-admin@lists.postgresql.org
Subject: Re: RHEL OS upgrade from 6.7 (Current version) to 8 version for Postgresql database

On a side note, shouldn't you be upgrading to CentOS Stream instead of
CentOS 8?

RH heard the wails of complaint; their solution is to license RHEL for free 
up on up to 16 servers per customer.

At least that's what Ars Technica says. 
https://arstechnica.com/gadgets/2021/01/centos-is-gone-but-rhel-is-now-free-for-up-to-16-production-servers/

On 3/19/21 2:42 PM, Dave Bolt wrote:
> This is the first I have heard about Centos Stream. I found an announcement dated 8 December 2020 saying that CentOS
Projectis shifting focus to CentOS Stream, and a LOT of comments and confusion.
 
> The main thing is that Stream apparently tracks Ahead of a current RHEL release.
> This may be a concern because I and many others use CentOS as a stable 'tried and tested' platform not a 'cutting
edge'platform.
 
>
> Of course, I may be just as confused as everyone else seems to be about what all this actually means.
>
> Getting a bit off topic here, so apologies if I'm upsetting anyone.
>
> Regards,
> Dave Bolt
>
> -----Original Message (extract) -----
> From: MichaelDBA [mailto:MichaelDBA@sqlexec.com]
> Sent: 19 March 2021 17:18
> To: Tom Lane
> Cc: ram pratap maurya; paul.foerster@gmail.com; pgsql-admin@lists.postgresql.org
> Subject: Re: RHEL OS upgrade from 6.7 (Current version) to 8 version for Postgresql database
>
> On a side note, shouldn't you be upgrading to CentOS Stream instead of
> CentOS 8?

-- 
Angular momentum makes the world go 'round.