Re: [INTERFACES] Re: M$-Access'97 and TIMESTAMPs

Oops! Here's a better way without the shared module.

-- Overload int4eq

create function int4eq(xid,int4)
returns bool
as ''
language 'internal';

create operator = (
leftarg=xid,
rightarg=int4,
procedure=int4eq,
commutator='=',
negator='<>',
restrict=eqsel,
join=eqjoinsel
);

David Hartwig wrote:

> Here is is what you will need. I hope you know how to compile a shared lib for your
> platform. This can be an adventure if you have not done it before. You will have to
> adjust the path in the CREATE FUNCTION statement to your lib dir. Run the SQL after you
> compile and install the shared lib. To test, do something like:
>
> SELECT * FROM foo WHERE xmin = {some_constant}
>
> I plan to submit a patch to make this a part of the 6.4 base release.
>
> Jose' Soares Da Silva wrote:
>
> > On Thu, 11 Jun 1998, Byron Nikolaidis wrote:
> >
> > > Jose',
> > >
> > > I got row versioning working with the "xmin" field. Since it is a system column, and
> > > automatically updates, you would not need triggers all over the place on every table.
> > > I made it a datasource option called "Row Versioning".
> > >
> > > It works well with Access except for two minor caveats:
> > >
> > > 1) The driver has to report the 'xmin' field in SQLColumns. There is no way around
> > > that I can see. Access, thus displays it. Users can of course hide the column if they
> > > hate looking at it. And Access won't let you type into this field which is good.
> > >
> > > 2) You have to create an '=' operator for the xid type on the postgres side since one
> > > does not already exist. I have the code to do it if you are interested (it is very
> > > small). For 6.4, we would make sure this operator is added.
> > >
> > Ok Byron, I think this is a good solution.
> > In this way we don't need to add a TIMESTAMP to every table there's already a
> > XMIN present.
> > In any way, what's happen with TIMESTAMPs ? May we have Access recognize it as
> > DATETIME or we can't because Access beleaves that's a ROWVER ?
> > I would like to try it. Please Byron may you send me the code for '=' operator
> > for xid type.
> > Jose'
>
> ------------------------------------------------------------------------
> /* Insight Distribution Systems - System V - Apr 1998 */
> static char accntnum_c[] = "@(#)accntnum.c 1.1 /sccs/sql/extend/s.accntnum.c 4/28/98 09:06:54";
>
> #include <stdio.h> /* for sprintf() */
> #include <string.h>
> #include "postgres.h"
> #include "utils/palloc.h"
>
> bool
> xidint4_eq(int32 arg1, int32 arg2)
> {
> return (arg1 == arg2);
> }
>
> ------------------------------------------------------------------------
> -- Insight Distribution Systems - System V - Apr 1998
> -- %W% :%P% %G% %U%"
>
> create function xidint4_eq(xid,int4)
> returns bool
> as '/ceo/pgsql/lib/xidint4.so'
> language 'c';
>
> create operator = (
> leftarg=xid,
> rightarg=int4,
> procedure=xidint4_eq,
> commutator='=',
> negator='<>',
> restrict=eqsel,
> join=eqjoinsel
> );