Subject: I suggest improving install steps for CentOS 8

From: Yasuhiro Horimoto <[email-masked]>
Date: Thu, 14 Nov 2019 11:36:30 +0900 (JST)

Hello,

I have found a problem with the following page.

page: https://www.postgresql.org/download/linux/redhat/

I tried install PostgreSQL12 into CentOS 8 as written on this page.
However, I couldn't install it by the following error.

# dnf install -y https://download.postgresql.org/pub/repos/yum/reporpms/EL-8-x86_64/pgdg-redhat-repo-latest.noarch.rpm
# dnf install -y postgresql12
Failed to set locale, defaulting to C
PostgreSQL 10 for RHEL/CentOS 8 - x8 100 kB/s | 539 kB     00:05
PostgreSQL 11 for RHEL/CentOS 8 - x8 121 kB/s | 629 kB     00:05
PostgreSQL 12 for RHEL/CentOS 8 - x8  91 kB/s | 471 kB     00:05
PostgreSQL 9.4 for RHEL/CentOS 8 - x  75 kB/s | 361 kB     00:04
PostgreSQL 9.5 for RHEL/CentOS 8 - x 108 kB/s | 425 kB     00:03
PostgreSQL 9.6 for RHEL/CentOS 8 - x  55 kB/s | 518 kB     00:09
No match for argument: postgresql12
Error: Unable to find a match

There is a workaround for this problem.
I executed a below command.
I could install it.

# dnf module disable postgresql

This problem has already reported to Red Hat Bugzilla.
(https://bugzilla.redhat.com/show_bug.cgi?id=1718201#c1)

However, this problem has been already closed.
Because it seems that is not a bug.

Therefore I suggest that add a workaround in this document like an
attachment.

Thanks,
diff --git a/templates/pages/download/linux/redhat.html b/templates/pages/download/linux/redhat.html
index 568085a..3b0cbaf 100644
--- a/templates/pages/download/linux/redhat.html
+++ b/templates/pages/download/linux/redhat.html
@@ -51,6 +51,9 @@ The PostgreSQL Yum Repository currently supports:
 <p><strong><sup>*</sup>Note</strong>: due to the shorter support cycle
 on Fedora, all supported versions of PostgreSQL are not available on this platform. We do not recommend
 using Fedora for server deployments.
+
+<p><strong><sup>*</sup>Note</strong>: PostgreSQL can't install in CentOS 8 or RedHat Enterprise 8 just execute the following steps.
+We need to execute "dnf module disable postgresql" before install the client package.
 </p>
 <p>
 To use the PostgreSQL Yum Repository, follow these steps:

---

From: Daniel Gustafsson <[email-masked]>
Date: Thu, 14 Nov 2019 10:29:01 +0100

Adding -www as this isn't a documentation issue but a website issue.

> On 14 Nov 2019, at 03:36, Yasuhiro Horimoto <[email-masked]> wrote:
> 
> Hello,
> 

Agreed, it's not a bug.

> +We need to execute "dnf module disable postgresql" before install the client package.

This doesn't explain what the problem is, and why the above command works (or
what side effects it may have).  I don't think it's a bad idea to mention this
problem on the page but we should phrase it in such a way that it's clear what
the underlying problem is, and what the fix means.  Linking to offical RPM docs
can be a good way too?

cheers ./daniel

---

From: Yasuhiro Horimoto <[email-masked]>
Date: Mon, 18 Nov 2019 16:21:05 +0900 (JST)

Hello,

Thank you for your comments.

I've fixed my patch according to your comments.
I attached it.

Thanks,

From: Daniel Gustafsson <[email-masked]>
Subject: Re: I suggest improving install steps for CentOS 8
Date: Thu, 14 Nov 2019 10:29:01 +0100

diff --git a/templates/pages/download/linux/redhat.html b/templates/pages/download/linux/redhat.html
index 568085a..27ee179 100644
--- a/templates/pages/download/linux/redhat.html
+++ b/templates/pages/download/linux/redhat.html
@@ -51,6 +51,12 @@ The PostgreSQL Yum Repository currently supports:
 <p><strong><sup>*</sup>Note</strong>: due to the shorter support cycle
 on Fedora, all supported versions of PostgreSQL are not available on this platform. We do not recommend
 using Fedora for server deployments.
+
+<p><strong><sup>*</sup>Note</strong>: PostgreSQL can't install in CentOS 8 or RedHat Enterprise 8 just execute the following steps.</br>
+This is due to the new package management system.</br>
+If there are the non-modular packages that match by name with modular packages, they are filtered out.</br>
+Therefore, we need to disable Modularity by executing "dnf module disable postgresql" or specify "module_hotfixes=true" in the .repo file in order to install with these steps.</br>
+See also this page: <a href="https://github.com/rpm-software-management/dnf/blob/master/doc/modularity.rst#package-filtering">rpm-software-management/dnf/doc/</a>
 </p>
 <p>
 To use the PostgreSQL Yum Repository, follow these steps:

---

From: Yasuhiro Horimoto <[email-masked]>
Date: Mon, 09 Dec 2019 18:21:32 +0900 (JST)

Hello,

Would this modification be acceptable?

Thanks,

From: Yasuhiro Horimoto <[email-masked]>
Subject: Re: I suggest improving install steps for CentOS 8
Date: Mon, 18 Nov 2019 16:21:05 +0900 (JST)

---

From: Devrim Gündüz <[email-masked]>
Date: Mon, 09 Dec 2019 12:11:26 +0000

Hi,

> Adding -www as this isn't a documentation issue but a website issue.

Adding Magnus :-)

Seriously speaking, for RHEL 8, we need to add 

dnf -qy module disable postgresql

command. Magnus, can you patch this when you can?

Cheers,
-- 
Devrim Gündüz
Open Source Solution Architect, Red Hat Certified Engineer
Twitter: @DevrimGunduz , @DevrimGunduzTR

---

From: Magnus Hagander <[email-masked]>
Date: Mon, 9 Dec 2019 13:17:36 +0100

> command. Magnus, can you patch this when you can?

Yeah, it seems like it would be better to add this as part of the
instructions rather than as a note on the side.

What is the normal time to do this, in the sequence. After the repository
rpm is installed but before client packages?

And is there any case you'd want to add the pg repositories but *not* do
this? I assume not?

-- 
 Magnus Hagander
 Me: https://www.hagander.net/ <http://www.hagander.net/>
 Work: https://www.redpill-linpro.com/ <http://www.redpill-linpro.com/>

---

From: Devrim Gündüz <[email-masked]>
Date: Mon, 09 Dec 2019 20:38:01 +0300

Hi,

> rpm is installed but before client packages?

Right.

Cheers,

---

From: Magnus Hagander <[email-masked]>
Date: Tue, 10 Dec 2019 21:00:06 +0100

> > rpm is installed but before client packages?
I have pushed an update for this to the site.

//Magnus

---

From: Yasuhiro Horimoto <[email-masked]>
Date: Wed, 11 Dec 2019 09:40:26 +0900 (JST)

Hello,

Thank you very much for your update.

I can successfully installed PostgreSQL
on CentOS 8 by this procedure.

Thanks,

From: Magnus Hagander <[email-masked]>
Subject: Re: I suggest improving install steps for CentOS 8
Date: Tue, 10 Dec 2019 21:00:06 +0100

---

From: Devrim Gündüz <[email-masked]>
Date: Wed, 11 Dec 2019 14:53:19 +0300

Hi Magnus,

> I have pushed an update for this to the site.

Thanks a lot!

Cheers,