From: Tom Lane <tgl@sss.pgh.pa.us>
To: pgsql-hackers@postgresql.org
Subject: Re: Race-like failure in recovery/t/009_twophase.pl
In-reply-to: <2588.1499028049@sss.pgh.pa.us>
References: <908.1498965681@sss.pgh.pa.us> <2588.1499028049@sss.pgh.pa.us>
Comments: In-reply-to Tom Lane <tgl@sss.pgh.pa.us>
	message dated "Sun, 02 Jul 2017 16:40:49 -0400"
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Date: Sun, 02 Jul 2017 17:10:31 -0400
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I wrote:
> Any ideas what's wrong there?

Hah: the answer is that query_hash's split() call is broken.
"man perlfunc" quoth

       split   Splits the string EXPR into a list of strings and returns that
               list.  By default, empty leading fields are preserved, and
               empty trailing ones are deleted.
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

In the case at hand, the SQL query returns something like
"|physical|||t|10338|||0/302B7E8" with normal timing, but with
enough delay in there, you get "|physical|||t|11542|||" which
triggers split's default behavior of ignoring the trailing empty
fields.  It looks like the way to get split to not do that is
to pass it a "limit" of -1.

			regards, tom lane


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