records using a sub form, i.e. entering a new order/orderlines or master
and
detail tables. The problem is caused by a SQL statement that Access97
makes
involving NULL. The syntax that fails is "column_name" = NULL. The
following attachment was provided by -Jose'-. It contains a very small
enhancement to gram.y that will allow Access97 to work properly with sub
forms. Can this enhancement be added to release 6.5?
<<gram.patch>>
Thanks, Michael
Ok. I made patches replacing all of "#if FALSE" or "#if 0" to "#ifdef
NOT_USED" for current. I have tested these patches in that the
postgres binaries are identical.
I search in the planner for the '\xFF' appending.
Finally I found in MakeIndexable() in gram.y
Attach a patch which removes the "<=" test in USE_LOCALE,
might make some queries a bit slower for us "locale-heads",
BUT correct result is more important.
regards,
--
-----------------
Göran Thyni
Included patches fix a portability problem of unsetenv() used in
6.4.2 multi-byte support. unsetenv() is only avaliable on FreeBSD and
Linux so I decided to replace with putenv().
a field was labelled as a primary key, the system automatically
created a unique index on the field. This patch extends it so
that the index has the indisprimary field set. You can pull a list
of primary keys with the followiing select.
SELECT pg_class.relname, pg_attribute.attname
FROM pg_class, pg_attribute, pg_index
WHERE pg_class.oid = pg_attribute.attrelid AND
pg_class.oid = pg_index.indrelid AND
pg_index.indkey[0] = pg_attribute.attnum AND
pg_index.indisunique = 't';
There is nothing in this patch that modifies the template database to
set the indisprimary attribute for system tables. Should they be
changed or should we only be concerned with user tables?
D'Arcy
INTERSECT and EXCEPT is available for postgresql-v6.4!
The patch against v6.4 is included at the end of the current text
(in uuencoded form!)
I also included the text of my Master's Thesis. (a postscript
version). I hope that you find something of it useful and would be
happy if parts of it find their way into the PostgreSQL documentation
project (If so, tell me, then I send the sources of the document!)
The contents of the document are:
-) The first chapter might be of less interest as it gives only an
overview on SQL.
-) The second chapter gives a description on much of PostgreSQL's
features (like user defined types etc. and how to use these features)
-) The third chapter starts with an overview of PostgreSQL's internal
structure with focus on the stages a query has to pass (i.e. parser,
planner/optimizer, executor). Then a detailed description of the
implementation of the Having clause and the Intersect/Except logic is
given.
Originally I worked on v6.3.2 but never found time enough to prepare
and post a patch. Now I applied the changes to v6.4 to get Intersect
and Except working with the new version. Chapter 3 of my documentation
deals with the changes against v6.3.2, so keep that in mind when
comparing the parts of the code printed there with the patched sources
of v6.4.
Here are some remarks on the patch. There are some things that have
still to be done but at the moment I don't have time to do them
myself. (I'm doing my military service at the moment) Sorry for that
:-(
-) I used a rewrite technique for the implementation of the Except/Intersect
logic which rewrites the query to a semantically equivalent query before
it is handed to the rewrite system (for views, rules etc.), planner,
executor etc.
-) In v6.3.2 the types of the attributes of two select statements
connected by the UNION keyword had to match 100%. In v6.4 the types
only need to be familiar (i.e. int and float can be mixed). Since this
feature did not exist when I worked on Intersect/Except it
does not work correctly for Except/Intersect queries WHEN USED IN
COMBINATION WITH UNIONS! (i.e. sometimes the wrong type is used for the
resulting table. This is because until now the types of the attributes of
the first select statement have been used for the resulting table.
When Intersects and/or Excepts are used in combination with Unions it
might happen, that the first select statement of the original query
appears at another position in the query which will be executed. The reason
for this is the technique used for the implementation of
Except/Intersect which does a query rewrite!)
NOTE: It is NOT broken for pure UNION queries and pure INTERSECT/EXCEPT
queries!!!
-) I had to add the field intersect_clause to some data structures
but did not find time to implement printfuncs for the new field.
This does NOT break the debug modes but when an Except/Intersect
is used the query debug output will be the already rewritten query.
-) Massive changes to the grammar rules for SELECT and INSERT statements
have been necessary (see comments in gram.y and documentation for
deatails) in order to be able to use mixed queries like
(SELECT ... UNION (SELECT ... EXCEPT SELECT)) INTERSECT SELECT...;
-) When using UNION/EXCEPT/INTERSECT you will get:
NOTICE: equal: "Don't know if nodes of type xxx are equal".
I did not have time to add comparsion support for all the needed nodes,
but the default behaviour of the function equal met my requirements.
I did not dare to supress this message!
That's the reason why the regression test for union will fail: These
messages are also included in the union.out file!
-) Somebody of you changed the union_planner() function for v6.4
(I copied the targetlist to new_tlist and that was removed and
replaced by a cleanup of the original targetlist). These chnages
violated some having queries executed against views so I changed
it back again. I did not have time to examine the differences between the
two versions but now it works :-)
If you want to find out, try the file queries/view_having.sql on
both versions and compare the results . Two queries won't produce a
correct result with your version.
regards
Stefan
