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From: Heikki Linnakangas <hlinnakangas@vmware.com>
To: Alexander Korotkov <aekorotkov@gmail.com>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Tomas Vondra <tv@fuzzy.cz>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: GIN improvements part 1: additional information
Date: Mon, 09 Dec 2013 11:18:13 +0200
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On 12/08/2013 09:56 PM, Alexander Korotkov wrote:
> On Fri, Nov 29, 2013 at 11:17 PM, Heikki Linnakangas <
> hlinnakangas@vmware.com> wrote:
>
>> I'll continue reviewing next week..

Got dragged into other things and didn't make any progress on this last 
week. I'm trying again now.

> Good. Thanks for debug and fixing bugs.
> Can I do anything for this patch now?

I wonder if we're leaving some money on the table, by using varbyte 
encoding. Googling around, there are many other compression methods out 
there for compressing integer deltas that compress better, and/or 
decompress faster.

Even if we use varbyte encoding, I wonder if it would be better to treat 
block + offset number as a single 48-bit integer, rather than encode 
them separately. That would allow the delta of two items on the same 
page to be stored as a single byte, rather than two bytes. Naturally it 
would be a loss on other values, but would be nice to see some kind of 
an analysis on that. I suspect it might make the code simpler, too.

- Heikki


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