Re: A general Q about index

On 07/16/2013 11:09 PM, soroosh sardari wrote:
> 
> Actually  I mean the index in the source code, I want to know how index
> is used in the backend for
> execution of some query.
> sorry my question is a bit ambiguous,
> I start to read "src/backend/access/index/genam.c", and I think maybe
> this file is not good way to start.
> let me write a bunch of question to illustrate my point,
> -How create an index for a table with specified field
> -How index is stored in a page
> -what module is responsible to fetch and swap out index pages
> -Is there a kind of abstract class for all variant of index?

Start with the documentation:

http://www.postgresql.org/docs/current/static/internals.html

particularly:

http://www.postgresql.org/docs/current/static/indexam.html
http://www.postgresql.org/docs/current/static/gist.html
http://www.postgresql.org/docs/current/static/catalog-pg-index.html
http://www.postgresql.org/docs/current/static/catalog-pg-am.html

That should give you the ground work to understand the source code a bit
better. Then feel free to return with specific questions you don't feel
are explained by the documentation or code comments and aren't obvious
from the code.
-- Craig Ringer                   http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services