Re: Always truncate segments before unlink

On Tue, Jul 6, 2010 at 9:59 AM, Takahiro Itagaki
<itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp> wrote:
>
> Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Truncating seems like an ugly kluge that's not fixing the real problem.
>> Why are there open descriptors for a dropped relation?  They should all
>> get closed as a consequence of relcache flush.
>
> Relcache will be flushed at the next command, but there could be some
> *idle backends* kept by connection pooling. They won't close dropped files
> until shared cache invalidation queue are almost filled, that might take
> long time.

Right. Since many connection poolers use LIFO method to manage the pooled
connections, this problem is very likely to happen.

> There might be another solution that we send PROCSIG_CATCHUP_INTERRUPT
> signal not only on the threshold of queue length but also on timeout,
> where the signal is sent when we have some old messages in the queue
> longer than 30sec - 1min.

REINDEX or something should not send PROCSIG_CATCHUP_INTERRUPT immediately?

Regards,

--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center