hash index improving v3

There's minor change against the previous one( http://archives.postgresql.org/pgsql-hackers/2008-07/msg01183.php ).
* merge branch master(Aug 16) into the patch
* clean code and make some comment
Performance result is here
http://wiki.postgresql.org/wiki/Gsoc08-hashindex

It seems hash index is a little better on index creation and selection.
But maybe  it's in the range of noise, I'm not sure.
I'd like to try it with a bigger dataset (e.g. table with 10GB) but there is not enough space in my computer.
Anyone interest can make a test on a bigger data set.

--
Best Regards,
Xiao Meng

DKERC, Harbin Institute of Technology, China
Gtalk: mx.cogito@gmail.com
MSN: cnEnder@live.com
http://xiaomeng.yo2.cn