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  1. pg_upgrade: Fix large object COMMENTS, SECURITY LABELS

  1. pg_upgrade loses security lables and COMMENTs on blobs

    Stephen Frost <sfrost@snowman.net> — 2017-02-21T16:26:55Z

    Greetings,

When pg_upgrade calls pg_dump, it passes in "--schema-only", which is
generally correct, except that this causes everything having to do with
large objects to be excluded.  That's still usually correct, because
pg_upgrade will simply copy the pg_largeobject and
pg_largeobject_metadata tables through to the new cluster as-is
(essentially treating them as if they were user tables).

Unfortunately, those tables aren't, actually, the only places that we
store information about large objects; the general-purpose tables like
pg_seclabel and pg_description can hold information about large objects
too.

What this means is that performing a pg_upgrade will result in any
security labels or comments on large objects being dropped.  This
seems to go back at least as far as 9.2, though I found it through the
pg_dump regression testing that I've been working on.

I haven't looked at trying to fix this yet, but I'm thinking the
approach to use will probably be to modify pg_dump to still call
getBlobs() when in binary-upgrade mode (regardless of the schema-only
flag) but then have dumpBlobs(), when in binary-upgrade mode, only
output the security labels and comments.  I hope that doesn't end up
causing some kind of chicken-and-egg problem..  Presumably the large
object tables are in place and correct before the dump is restored, so I
think this will work.

Just wanted to get a note out to -hackers about the issue, I'll see
about getting a fix written up for it soon.

Thanks!

Stephen

  2. Re: pg_upgrade loses security lables and COMMENTs on blobs

    Stephen Frost <sfrost@snowman.net> — 2017-02-23T15:36:37Z

    All,

* Stephen Frost (sfrost@snowman.net) wrote:
> Just wanted to get a note out to -hackers about the issue, I'll see
> about getting a fix written up for it soon.

Attached is a patch which addresses this issue.  I'm not terribly
pleased with it, but I also haven't got any great ideas of what else to
do.  Suggestions welcome, of course.

Otherwise, I'll plan to start working on the back-branch changes for
this soon.

Thanks!

Stephen

  3. Re: pg_upgrade loses security lables and COMMENTs on blobs

    Bruce Momjian <bruce@momjian.us> — 2017-02-28T01:44:40Z

    On Thu, Feb 23, 2017 at 10:36:37AM -0500, Stephen Frost wrote:
> All,
> 
> * Stephen Frost (sfrost@snowman.net) wrote:
> > Just wanted to get a note out to -hackers about the issue, I'll see
> > about getting a fix written up for it soon.
> 
> Attached is a patch which addresses this issue.  I'm not terribly
> pleased with it, but I also haven't got any great ideas of what else to
> do.  Suggestions welcome, of course.
> 
> Otherwise, I'll plan to start working on the back-branch changes for
> this soon.

Yeah, this is probably the best you can do.   Your analysis of how we
used to treat large objects is correct, and was never adjusted for the
changes you outlined.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

+ As you are, so once was I.  As I am, so you will be. +
+                      Ancient Roman grave inscription +

  4. Re: pg_upgrade loses security lables and COMMENTs on blobs

    Stephen Frost <sfrost@snowman.net> — 2017-03-03T15:08:18Z

    Bruce,

* Bruce Momjian (bruce@momjian.us) wrote:
> On Thu, Feb 23, 2017 at 10:36:37AM -0500, Stephen Frost wrote:
> > * Stephen Frost (sfrost@snowman.net) wrote:
> > > Just wanted to get a note out to -hackers about the issue, I'll see
> > > about getting a fix written up for it soon.
> > 
> > Attached is a patch which addresses this issue.  I'm not terribly
> > pleased with it, but I also haven't got any great ideas of what else to
> > do.  Suggestions welcome, of course.
> > 
> > Otherwise, I'll plan to start working on the back-branch changes for
> > this soon.
> 
> Yeah, this is probably the best you can do.   Your analysis of how we
> used to treat large objects is correct, and was never adjusted for the
> changes you outlined.

Great, thanks, I'll be pushing this to all the branches soon, still
testing.

Thanks again!

Stephen