On Thursday, October 18, 2012 06:12:02 AM Kevin Grittner wrote:
> Kevin Grittner wrote:
> > Hmm. The comment is probably better now, but I've been re-checking
> > the code, and I think my actual code change is completely wrong.
> > Give me a bit to sort this out.
>
> I'm having trouble seeing a way to make this work without rearranging
> the code for concurrent drop to get to a state where it has set
> indisvalid = false, made that visible to all processes, and ensured
> that all scans of the index are complete -- while indisready is still
> true. That is the point where TransferPredicateLocksToHeapRelation()
> could be safely called. Then we would need to set indisready = false,
> make that visible to all processes, and ensure that all access to the
> index is complete. I can't see where it works to set both flags at
> the same time. I want to sleep on it to see if I can come up with any
> other way, but right now that's the only way I'm seeing to make DROP
> INDEX CONCURRENTLY compatible with SERIALIZABLE transactions. :-(
In a nearby bug I had to restructure the code that in a way thats similar to
this anyway, so that seems fine. Maybe you can fix the bug ontop of the two
attached patches?
Greetings,
Andres
--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
