Re: 'tuple concurrently updated' error for alter role ... set

On May 13, 2011, at 2:07 AM, Alexey Klyukin wrote:

> On May 13, 2011, at 1:28 AM, Tom Lane wrote:
> 
>> 
>> We're not likely to do that, first because it's randomly different from
>> the handling of every other system catalog update, and second because it
>> would serialize all updates on this catalog, and probably create
>> deadlock cases that don't exist now.  (BTW, as the patch is given I'd
>> expect it to still fail, though perhaps with lower probability than
>> before.  For this to actually stop all such cases, you'd have to hold
>> the lock till commit, which greatly increases the risks of deadlock.)
> 
....
>> 
>> I see no particular reason why conflicting updates like those *shouldn't*
>> be expected to fail occasionally.
> 
> Excellent question, I don't have enough context to properly answer that (other
> than a guess that an unexpected transaction rollback is too unexpected :))
> Let me ask the customer first.

The original use case is sporadical failures of some internal unit tests due
to the error message in subject. 

--
Alexey Klyukin
The PostgreSQL Company - Command Prompt, Inc.