Date: Wed, 31 Oct 2018 15:48:02 -0700
From: Andres Freund <andres@anarazel.de>
To: Michael Paquier <michael@paquier.xyz>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>,
	"Joshua D. Drake" <jd@commandprompt.com>,
	pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: replication_slots usability issue
Message-ID: <20181031224802.lamhfjil7uwpfiee@alap3.anarazel.de>
References: <56672097-711c-126a-a63e-04e7940110ad@commandprompt.com>
 <20181029190218.uejy5cvgzygwrguy@alvherre.pgsql>
 <20181029191304.lbsmhshkyymhw22w@alap3.anarazel.de>
 <20181030025109.GD1644@paquier.xyz>
 <20181030175254.wqircsg36vblpmw5@alap3.anarazel.de>
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On 2018-10-30 10:52:54 -0700, Andres Freund wrote:
> On 2018-10-30 11:51:09 +0900, Michael Paquier wrote:
> > On Mon, Oct 29, 2018 at 12:13:04PM -0700, Andres Freund wrote:
> > > I don't think this quite is the problem. ISTM the issue is rather that
> > > StartupReplicationSlots() *needs* to check whether wal_level > minimal,
> > > and doesn't. So you can create a slot, shutdown, change wal_level,
> > > startup. A slot exists but won't work correctly.
> > 
> > It seems to me that what we are looking for is just to complain at
> > startup if we find any slot data and if trying to start up with
> > wal_level = minimal.
> 
> Right, we really should just call CheckSlotRequirements() before doing
> so. I'll make it so, once I'm actually awake and had some coffee.

And done.  Thanks for the report JD.

- Andres