Date: Fri, 27 May 2016 16:24:56 -0400
From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Nikolay Shaplov <n.shaplov@postgrespro.ru>,
	pgsql-hackers@postgresql.org
Subject: Re: [PROPOSAL] Move all am-related reloption code into
 src/backend/access/[am-name] and get rid of relopt_kind
Message-ID: <20160527202456.GA717848@alvherre.pgsql>
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Tom Lane wrote:
> Alvaro Herrera <alvherre@2ndquadrant.com> writes:
> > Nikolay Shaplov wrote:
> >> Story start from the point that I found out that a.m. can not forbid changing 
> >> some of it's reloptions with ALTER INDEX command.
> 
> > Hmm, this sounds like a bug to me.  In BRIN, if you change the
> > pages_per_range option for an existing index, the current index
> > continues to work because the value used during the last index build is
> > stored in the metapage.  Only when you reindex after changing the option
> > the new value takes effect.
> 
> > I think Bloom should do likewise.
> 
> AFAICT, Bloom *does* do that.  The reloptions are only consulted directly
> while initializing the metapage.

Ah, clearly I misunderstood what he was saying.

> I think Nikolay's complaint is essentially that there should be a way
> for an AM to forbid ALTER INDEX if it's not going to support on-the-fly
> changes of a given reloption.  That might be a helpful usability
> improvement, but it's only a usability improvement not a bug fix.

I can get behind that idea, but this also says I should get away from
this thread until 10dev opens.

-- 
Álvaro Herrera                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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