Re: Bugs in CREATE/DROP INDEX CONCURRENTLY

On 18 October 2012 10:20, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
> 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?

First patch and first test committed.

Working on second patch/test.

--
Simon Riggs http://www.2ndQuadrant.com/
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