On Wed, Oct 21, 2009 at 2:41 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
>> On Wed, Oct 21, 2009 at 12:27 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>>> The post-connect SET still seems like the best choice to me.
>
>> Are we really thinking about interposing an additional server
>> round-trip on every connection for such a marginal feature (to
>> paraphrase yourself)? That doesn't seem like a good trade-off.
>
> Only connections that are actually using the feature. It doesn't
> bother me that much --- before 7.4 we had *multiple* round trips
> involved in a connection start,
OK, but surely we're not saying that was good? I presume we fixed
that for a reason and want it to stay fixed.
> and anyway backend startup is a
> pretty dang heavyweight operation.
>
> If you are concerned about that you should certainly not be advocating
> multiple connection tries instead. That's a lot of round trips too,
> plus you are paying repeated fork and backend-startup overhead.
Yeah, I don't like that either, but at least it only happens when you
have a server-version mismatch, and even then (if we accept Dave's
other suggestion) only for releases prior to 8.5. I'd rather it be
dog-slow in a rare situation that I can avoid through proper
configuration than moderately slow in a common situation that I can't
escape short of not using the feature.
Of course, the difficulty of implementation is another issue...
...Robert