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RE: [PATCH] WC DB verification 1

From: Julian Foad <julian.foad_at_wandisco.com>
Date: Tue, 10 May 2011 09:34:47 +0100

On Tue, 2011-05-10 at 02:12 +0200, Bert Huijben wrote:
>
> > -----Original Message-----
> > From: Mark Phippard [mailto:markphip_at_gmail.com]
> > Sent: dinsdag 10 mei 2011 1:16
> > To: Julian Foad
> > Cc: dev_at_subversion.apache.org
> > Subject: Re: [PATCH] WC DB verification 1
> >
> > Could we tie it into cleanup? Then other tools like TortoiseSVN,
> > Subclipse, AnkhSVN could invoke it too.
> >
> >
> > On Mon, May 9, 2011 at 6:30 PM, Julian Foad <julian.foad_at_wandisco.com>
> > wrote:
> > > I'm planning to commit the attached wc-db-verification-1.patch, subject
> > > to any advice on how to best fit it in to the code base or other
> > > concerns, in order to get a DB "self-check" function started.
> > >
> > > I think we need something like this. Earlier today I found that "svn
> > > status" showed I had a clean, single-rev WC, while "svnversion" said it
> > > was mixed-rev and switched. Investigation showed there were orphaned
> > > base node rows in the DB which weren't seen by "svn st" but were seen by
> > > "svnversion". I'm not interested in how that particular state came to
> > > be, as I've run hundreds of buggy trunk builds on this WC over many
> > > months. What I do want is to be able to run a set of checks on a DB
> > > that detects basic rule violations like that.
> > >
> > > Decisions about when and how to run it can come later. Of course if we
> > > plan to run it frequently and automatically that would mean we'd want to
> > > make sure it only did fast checks and is efficiently coded whereas if it
> > > remains a manual intervention for devs then that's no concern. Thoughts
> > > about this are welcome too.
>
> I would suggest adding a new function for this purpose; and maybe a separate
> program to call it for our beta cycle.

I'm happy to make a separate program to call it if that's what we
prefer.

> This code should never be necessary once we call the db stable.

The idea is similar to validating postconditions whenever we modify the
DB. It is "assertions" but at a higher level than ones we would put
in-line in the code. It will help to make the DB stable. It should be
called only during testing and debugging, but should remain available
during testing and debugging forever.

> And making
> the normal cleanup very slow makes it less useful for its normal task.

Sure.

> I'm not sure about what you are testing in this initial patch though: The
> only functions that can insert rows in NODES always use
> svn_relpath_dirname() for creating parent_relpath, so if you find databases
> where that set incorrectly you can be 100% certain those databases that are
> hand edited.

It's verifying conditions that "must be true". It should catch any case
where a DB has been hand-edited or where we have accidentally added some
kind of row-insertion code that is broken.

> The parent exists checks are more useful, but should also look at op-depth,
> etc. to really find problems. (The op-depth root must always exist and every
> intermediate too)

Yes, this is exactly the kind of useful extensions that I want us to
make.

- Julian
Received on 2011-05-10 10:35:24 CEST

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