Re: LWLock statistics collector

ITAGAKI Takahiro <itagaki.takahiro@oss.ntt.co.jp> writes:
> Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> This seems fairly invasive, as well as confused about whether it's an
>> #ifdef'able thing or not.  You can't have system views and pg_proc
>> entries conditional on a compile-time #ifdef, so in a default build
>> we would have a lot of nonfunctional cruft exposed to users.

> Is it acceptable if pg_stat_lwlocks view and other functions are not
> installed and invisible when LWLOCK_STAT is not defined? We don't have
> such a feature now, but we can.

Then you'd need an initdb to go between having stats and not, which
carries its own downsides.  If I thought there were a wide market for
this then I'd say sure, let's just have it there ... but I don't.

I think the actual wave of the future for analyzing behavior at the
LWLock level is going to be DTrace.  It seems way more flexible than
an aggregate-statistics view can be.
        regards, tom lane