Added needed include file.

cache.  I found if I manually added a line to flush the whole relation
cache, the assert error disappeared.  Looking through the code, I found
that the relation cache is flushed at the end of each query if the
reference count is zero for the relation.  However, printf's showed that
the rd_relcnt(reference count) for the accessed query was not returning
to zero after each query.

It turns out the parser was doing a heap_ropen in parser/analyze.c to
get information about the table's columns, but was not doing a
heap_close.

This was causing the query after the ALTER TABLE ADD to see the old
table structure, and the executor's assert was reporting the problem.

Previously Postgres95 wouldn't accept 'order by' clauses with fields
referred to as '<table>.<field>', e.g.:

        select t1.field1, t2.field2 from table1 t1, table2 t2
                order by t2.field2;

This syntax is required by the ODBC SQL spec.

Submitted by: Dan McGuirk <mcguirk@indirect.com>

While a normal SELECT statement can contain a GROUP BY clause, a cursor
declaration cannot. This was not the case in PG-1.0. Was there a good
reason why this was changed? Are cursors being phased out? Is there any way
to get data with just a SELECT (and without a DECLARE CURSOR ...)?

The patch below seems to fix things. If anyone can see a problem with it,
please let me know. Thanks.

Submitted by:  David Smith <dasmith@perseus.tufts.edu>

The updating of array fields is broken in Postgres95-1.01, An array can
be only replaced with a new array but not have some elements modified.
This is caused by two bugs in the parser and in the array utilities.
Furthermore it is not possible to update array with a base type of
variable length.


- submitted by: Massimo Dal Zotto <dz@cs.unitn.it>

I have written some patches which add support for NULLs to Postgres95.
In fact support for NULLs was already present in postgres, but it had been
disabled because not completely debugged, I believe. My patches simply add
some checks here and there. To enable the new code you must add -DNULL_PATCH
to CFLAGS in Makefile.global. After recompiling you can do things like:

insert into a (x, y) values (1, NULL);
update a set x = NULL where x = 0;

You can't still use a "where x=NULL" clause, you must use ISNULL instead.
This could probably be an easy fix to do.




Submitted by: Massimo Dal Zotto <dz@cs.unitn.it>