From: Tom Lane <tgl@sss.pgh.pa.us>
To: Fabien COELHO <coelho@cri.ensmp.fr>
cc: PostgreSQL Developers <pgsql-hackers@postgresql.org>
Subject: Re: Fixing pgbench's logging of transaction timestamps
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 <alpine.DEB.2.20.1701011128380.15074@lancre>
Comments: In-reply-to Fabien COELHO <coelho@cri.ensmp.fr>
	message dated "Sun, 01 Jan 2017 12:53:13 +0100"
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Date: Sun, 01 Jan 2017 15:22:13 -0500
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Fabien COELHO <coelho@cri.ensmp.fr> writes:
>> 3. Forget about using the instr_time result and just have doLog() execute
>> gettimeofday() to obtain the timestamp to print.  This is kind of
>> conceptually ugly, but realistically the added overhead is probably
>> insignificant.  A larger objection might be that on Windows, the result
>> of gettimeofday() isn't very high precision ... but it'd still be a huge
>> improvement over the non-answer you get now.

> Yep.

>> I'm inclined to think that #2 isn't a very good choice; it appears to
>> preserve the current behavior but really doesn't.  So we should either
>> change the behavior as in #1 or expend an extra system call as in #3.
>> Preferences?

> Marginal preference for #3 for KIS? Otherwise any three options seems 
> better than the current status.

OK, done that way.

BTW, why is it that the --aggregate-interval option is unsupported on
Windows?  Is that an artifact of the same disease of assuming too much
about how instr_time is represented?  I don't see any very good reason
for it other than the weird decision to store the result of
INSTR_TIME_GET_DOUBLE in a "long", which seems rather broken in any case.

			regards, tom lane


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