Re: Review: B-Tree emulation for GIN

On Fri, 2008-12-19 at 13:26 +0300, Teodor Sigaev wrote:
> Updated patch.

I have merged this with HEAD, written a brief document (which is mostly
a copy of the btree-gist page), added the module to the contrib
Makefile, and made some very minor changes. Patch attached.

A couple comments:

1. Right now, to implement "less than" you need to start at the
beginning of the index and scan until you reach the supplied query
datum. This is because GIN doesn't support backwards scans
( http://archives.postgresql.org/pgsql-hackers/2008-07/msg01146.php ).

Unfortunately, that means numeric is not supportable for btree-gin
because there is no left-most value from which to start the scan. Do you
see an easy workaround to support numeric?

2. Why do you create a shell type "int32" from btree_gin.sql? I tried
doing a search-and-replace to use "int4" instead, and it seems to work
fine (and eliminates the warnings). I left it with int32 in my version
of the patch because I thought you may have some reason for using it.

Regards,
Jeff Davis