Re: EXPLAIN BUFFERS - Mailing list pgsql-hackers

From Robert Haas
Subject Re: EXPLAIN BUFFERS
Date
Msg-id 603c8f070912132013r2142226ao19f00c75d5e9ef29@mail.gmail.com
Whole thread Raw
In response to Re: EXPLAIN BUFFERS  (Takahiro Itagaki <itagaki.takahiro@oss.ntt.co.jp>)
List pgsql-hackers
On Sun, Dec 13, 2009 at 10:00 PM, Takahiro Itagaki
<itagaki.takahiro@oss.ntt.co.jp> wrote:
>> Two other thoughts:
>>
>> 1. It doesn't appear that there is any provision to ever zero
>> pgBufferUsage.  Shouldn't we do this, say, once per explain, just to
>> avoid the possibility of overflowing the counters?
>
> I think the overflowing will not be a problem because we only use
> the differences of values. The delta is always corrent unless we use
> 2^32 buffer accesses during one execution of a node.

Hmm... you might be right.  I'm not savvy enough to know whether there
are any portability concerns here.

Anyone else know?

...Robert


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