Re: access method: are disk pages mandatory? - Mailing list pgsql-hackers

From Heikki Linnakangas
Subject Re: access method: are disk pages mandatory?
Date
Msg-id 4C222949.9090305@enterprisedb.com
Whole thread Raw
In response to access method: are disk pages mandatory?  (Leonardo F <m_lists@yahoo.it>)
Responses Re: access method: are disk pages mandatory?  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
On 23/06/10 18:17, Leonardo F wrote:
> in bufpage.h:
>
> "all blocks written out by an access method must be disk pages"
>
> but in
> http://www.postgresql.org/docs/8.4/static/storage-page-layout.html
>
> "Actually, index access methods need not use this page format. All the
> existing index methods do use this basic format, but the data kept on
> index metapages usually doesn't follow the item layout rules."
>
> I'm not getting it: am I supposed to use the "disk page format" when
> writing an index access method, or it's just a "good practice" because
> it makes the handling easier? Given the docs it looks "recommended",
> but the comment on the code sounds more "mandatory".

It's recommened because it makes life easier. Even if you don't use the 
normal page format, I think you need to have the LSN at the beginning of 
the page. The rest is up to you.

--   Heikki Linnakangas  EnterpriseDB   http://www.enterprisedb.com


pgsql-hackers by date:

Previous
From: Hitoshi Harada
Date:
Subject: Re: Partitioning syntax
Next
From: "Kevin Grittner"
Date:
Subject: Re: Partitioning syntax