Re: Avoiding deadlocks ...

On 8/20/10 8:23 AM, Marko Tiikkaja wrote:
> On 2010-08-20 6:19 PM, Kevin Grittner wrote:
>> Marko Tiikkaja<marko(dot)tiikkaja(at)cs(dot)helsinki(dot)fi> wrote:
>>
>>> I think truly serializable transactions still need to SELECT FOR
>>> SHARE here for foreign keys to work, no?
>>
>> That depends on how you look at it. The SSI patch that Dan and I
>> have been working on doesn't attempt to change the implementation
>> techniques for foreign keys, because SSI only enforces integrity
>> among serializable transactions -- and we want foreign keys to be
>> enforced regardless of the transaction isolation levels used.

Ok, then that's not a fix for this particular problem. This case is a
good example, though, of showing how deadlocks are the most expensive
type of serialization failure, and thus models which avoid deadlocks (in
favor of other kinds of blocking and/or serialization errors) are desirable.

--
-- Josh Berkus
PostgreSQL Experts Inc.
http://www.pgexperts.com