Re: Physical block structure in PostgreSQL

In article <1152783428(dot)682416(dot)237320(at)p79g2000cwp(dot)googlegroups(dot)com>,
Spendius <spendius(at)muchomail(dot)com> wrote:

% (I read the pages
% http://www.postgresql.org/docs/8.1/interactive/storage.html
% and saw things regarding files and "pages" that are "usually 8k"-big
% etc. but
% saw no further info about "blocks" - they speak of "items" here: what
% is it ?)

An item is the thing that's stored on the page. For instance, a database
table is stored in a bunch of pages in some file. Each row in the
table is stored as an item on a page, starting with a HeapTupleHeaderData.
The structure of an item for an index page might be different, though.

I found there was enough information in the section you cite to write a
simple data dumping tool in an emergency a while ago.
--

Patrick TJ McPhee
North York Canada
ptjm(at)interlog(dot)com