Re: pg_upgrade support is broken?

On Fri, 2014-08-01 at 22:15 +0800, Craig Ringer wrote:

Hi,

you may be interested about Pavel's recent work on postgresql-setup [1]
that we are using in Fedora and planing to use in RHEL.

There is a lot of work to support migration scenarios from different
versions.

[1] https://praiskup.fedorapeople.org/proj/postgresql-setup/

> Hi
>
> While reading the setup script, I noticed that to initdb the new
> cluster
> for pg_upgrade runs the following:
>
> # Perform initdb on the new server
> $PGENGINE/postgresql92-setup initdb
>
>
> Also, PREVPGENGINE isn't referenced; instead the pg_upgrade code uses
> PGPREVENGINE .
>
> This suggests that pg_upgrade support via the initscript has been
> broken
> throughout 9.3 and is still broken in 9.4, even for direct upgrades
> from
> the immediately previous major.
>
> It also uses 'su' instead of 'runuser', so I think it'd have issues
> on
> SELinux.
>
>
>
> It doesn't look like upgrades from other than the immediately
> previous
> major could ever have worked:
>
> - Support for specifying a non-default version to upgrade seems
> broken.
> Lots of the code continues to use $PREVMAJORVERSION despite it not
> being
> set if the user passes a $OLD_SERVICE_NAME argument.
>
> - it assumes that the previous binaries are in
> /usr/pgsql-$PREVMAJORVERSION/bin but they aren't if the user passed a
> $OLD_SERVICE_NAME other than that of $PREVMAJORVERSION
>
> - The issue with PREVPGENGINE vs PGPREVENGINE above
>
>
>
>
> Also, $OLD_SERVICE_NAME must be the basename of the
> initscript/service
> control file, e.g. postgresql-9.3 , not just "9.3". This isn't super
> obvious from the help.
>
>
> Support for upgrading from the immediately prev version looks to be
> fixable by replacing:
>
>
> # Perform initdb on the new server
> $PGENGINE/postgresql92-setup initdb
>
> with
>
> # Perform initdb on the new server
> $PGENGINE/postgresql${PREVMAJORVERSION/.}-setup initdb
>
> + using "$SU" instead of "su"
>
>
> Fixing upgrading from earlier versions also needs PREVMAJORVERSION to
> be
> overridden if the user specifies a control file explicitly and a
> bunch
> of other fixes.
>
> I attach a majorly reworked script for your review and comment. I
> haven't done much testing yet.
>
> It requires the rpm builds script to sub in some new variables:
>
> PREVMAJORVERSION=%{prevmajorversion}
> PGUNITNAME=%{unitname}
> PGPACKAGENAME=%{name}
>
>
> so a wrapper like:
>
> substitute_vars() {
> # Insert RPM variables into shell scripts
> sed -e 's|^PGVERSION=.*$|PGVERSION=%{version}|' \
> -e 's|^PGENGINE=.*$|PGENGINE=%{pgbaseinstdir}/bin|' \
> -e 's|^PGUNITNAME=.*$|PGUNITNAME=%{unitname}|' \
> -e
> 's|^PREVMAJORVERSION=.*$|PREVMAJORVERSION=%{prevmajorversion}|' \
> -e 's|^PGPACKAGENAME=.*$|PGPACKAGENAME=%{name}|' \
> -e 's|^PGDOCDIR=.*$|PGDOCDIR=%{_pkgdocdir}|' \
> < "$1" > "$2"
> }
>
> # prep the setup script, including insertion of some values it needs
> substitute_vars "%{SOURCE17}" "%{name}-setup"
>
>
>
> might be useful.
>
>
>
>
>
>
> BTW, the README.rpm-dist looks like it's a victim of some copy-and
> -paste
> too; see:
>
>
> ```
> In 9.1+, the RPMs also support in-place upgrade from th immediately
> previous major release. Currently, you can upgrade in-place
> from 9.2.x to 9.4.x. Just run:
> $ /usr/pgsql-9.4/bin/postgresql94-setup upgrade
>
> Please note that 9.2 and 9.4 contrib RPMs needs to be installed for
> this
> feature to work.
> ```
>
> That should be "9.3" not "9.2" and there's a typo in "th[e]".
>
>
>
> Anyway. Thoughts on the updated scripts? I've combined the sysv and
> systemd scripts to reduce duplication.
>