From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alvaro Herrera <alvherre@2ndquadrant.com>
cc: pgbf@twiska.com, Kyotaro Horiguchi <horikyota.ntt@gmail.com>,
        masao.fujii@oss.nttdata.com, pgsql-hackers@lists.postgresql.org
Subject: Re: min_safe_lsn column in pg_replication_slots view
In-reply-to: <20200710234037.GA24580@alvherre.pgsql>
References: <20200710234037.GA24580@alvherre.pgsql>
Comments: In-reply-to Alvaro Herrera <alvherre@2ndquadrant.com>
	message dated "Fri, 10 Jul 2020 19:40:37 -0400"
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Date: Sat, 11 Jul 2020 10:27:53 -0400
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Alvaro Herrera <alvherre@2ndquadrant.com> writes:
> On 2020-Jul-09, Alvaro Herrera wrote:
>> I think we should define InvalidXLogSegNo to be ~((uint64)0) and add a
>> macro to test for that.

> That's overkill really.  I just used zero.  Running
> contrib/test_decoding under valgrind, this now passes.

> I think I'd rather do away with the compare to zero, and initialize to
> something else in GetWALAvailability, though.  What we're doing seems
> unclean and unclear.

Is zero really not a valid segment number?

			regards, tom lane