Re: Race-like failure in recovery/t/009_twophase.pl

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Race-like failure in recovery/t/009_twophase.pl
Date: 2017-07-02 21:10:31
Message-ID: 14837.1499029831@sss.pgh.pa.us
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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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