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Re: Copy-To (forward reference) info in FSFS or BDB?

From: Julian Foad <julianfoad_at_btopenworld.com>
Date: Wed, 11 Nov 2009 13:51:14 +0000

On Wed, 2009-11-11 at 14:33 +0100, Branko ─îibej wrote:
> Branko ─îibej wrote:
> > Julian Foad wrote:
> >
> >> For obliteration, I need to be able to find all back-references from
> >> newer revisions to the node-rev I'm obliterating.
> >>
> >> Did we ever get anywhere with implementing a table to cache forward
> >> references ("copy-to")?
> >
> > No ... and IIRC building that list is one of the more expensive
> > operations you can think of.

However expensive it is, it's worth it in the long run.

> > You're going to add forward references, right? That will make some
> > people very happy. :)

Looks like I'll have to.

Is this diagram of the FS structure still accurate?
<http://homepages.paradise.net.nz/~ejrh/subversion/mysql/> (The diagram
is in Edmund Horner's mqsql backend design (2004) but I think he
explains there that it's just the then-current design except with skel
lists exploded out as separate tables.)

Anyone know of any diagram I could look at that shows our FS structure
like that one does, or like the txn-tree diagrams in www/design.html
except also showing how copy-ids etc. link up between revisions?

> Oh by the way, once you have forward references, you'll have to adjust
> those during obliteration, too.


Received on 2009-11-11 14:51:41 CET

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