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Re: More fun with GIN lossy-page pointers

From: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Oleg Bartunov <oleg(at)sai(dot)msu(dot)su>, Teodor Sigaev <teodor(at)sigaev(dot)ru>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: More fun with GIN lossy-page pointers
Date: 2010-08-01 01:35:51
Message-ID: 1280626360-sup-595@alvh.no-ip.org (view raw or flat)
Thread:
Lists: pgsql-hackers
Excerpts from Tom Lane's message of sáb jul 31 09:57:13 -0400 2010:

> So far as I can see, it's impossible to handle this situation when
> examining only one TID per stream with no lookahead.  Choosing to
> advance the second stream would obviously fail in many other cases,
> so there is no correct action.  The only reasonable way out is to
> forbid the case --- that is, decree that a keystream may *not*
> contain both lossy and nonlossy pointers to the same page.

Would it make sense to order the streams differently?  I mean, what if
whole-page pointers in the lossy stream are processed before regular ones?
(I am thoroughly unfamiliar with this stuff, so forgive me if I've
gotten the concepts and terminology all wrong)

-- 
Álvaro Herrera <alvherre(at)commandprompt(dot)com>
The PostgreSQL Company - Command Prompt, Inc.
PostgreSQL Replication, Consulting, Custom Development, 24x7 support

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