Re: GIN improvements part 1: additional information

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От Alexander Korotkov
Тема Re: GIN improvements part 1: additional information
Дата
Msg-id CAPpHfdts_8PAo_DjASEUJFznPGgauqjDo_nQW1BQAZR_u4bqmw@mail.gmail.com
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Ответ на Re: GIN improvements part 1: additional information  (Alvaro Herrera <alvherre@2ndquadrant.com>)
Ответы Re: GIN improvements part 1: additional information
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On Fri, Dec 20, 2013 at 11:43 PM, Alvaro Herrera <alvherre@2ndquadrant.com> wrote:
Heikki Linnakangas escribió:

> I believe that eliminates all encodings in the Simple family, as
> well as PForDelta, and surprisingly also Rice encoding. For example,
> if you have three items in consecutive offsets, the differences
> between them are encoded as 11 in rice encoding. If you remove the
> middle item, the encoding for the next item becomes 010, which takes
> more space than the original.

I don't understand this.  If you have three consecutive entries, and the
differences between them are 11, you need to store two 11s.  But if you
have two items, you only need to store 010 once.  So the difference is
larger, but since you need to store only one of them then overall it's
still shorter than the original.  No?

I believe Heikki mean both differences are encoded as 11, each one is 1.

------
With best regards,
Alexander Korotkov. 

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