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

Jan

LOCK TABLE IN ... MODE
...implemented

Initial attempt to clean up the code...

Switch sprintf() to snprintf()
Remove any/all #if 0 -or- #ifdef NOT_USED -or- #ifdef FALSE sections of
	code

    parameters. With it applied a function like

    CREATE FUNCTION getname(oid8, int4) RETURNS name AS
        'SELECT typname FROM pg_type WHERE oid = $1[$2]'
        LANGUAGE 'sql';

    is possible. Mainly I need this to enable array references in
    expressions for PL/pgSQL. Complete regression test ran O.K.

Jan

planner/optimizer/executor.  It isn't.
Besides, most of the removed code consists of comments about how
it's not right.

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

>       these patches define the UNLISTEN sql command. The code already
>       existed but it was unknown to the parser. Now it can be used
>       like the listen command.
>       You must make clean and delete gram.c and parser.h before make.

if MULTIBYTE is not enabled. So be sure to run initdb.

o these patches are made against the latest source tree (after
Bruce's massive patch, I think) BTW, I noticed that after running
regression, the oid field of pg_type seems disappeared.

	regression=> select oid from pg_type; ERROR:  attribute
	'oid' not found

this happens after the constraints test. This occures with/without
my patches. strange...

o pg_database_mb.h, pg_class_mb.h, pg_attribute_mb.h are no longer
used, and shoud be removed.

o GetDatabaseInfo() in utils/misc/database.c removed (actually in
#ifdef 0). seems nobody uses.

t-ishii@sra.co.jp

From: Jan Wieck <jwieck@debis.com>

Hi,

    as  proposed here comes the first patch for the query rewrite
    system.

  <for details, see archive dated Mon, 17 Aug 1998>

From: David Hartwig <daybee@bellatlantic.net>

I have attached a patch to allow GROUP BY and/or ORDER BY function or
expressions.  Note worthy items:

1. The expression or function need not be in the target list.
Example:
            SELECT  name FROM foo GROUP BY lower(name);

2.   Simplified the grammar to use expressions only.

3.  Cleaned up earlier patch in this area to make use of existing
utility functions.

3.  Reduced some of the members in the SortGroupBy parse node.   The
original data members were redundant with the new expression node.
(MUST do a "make clean" now)

4.  Added a new parse node "JoinUsing".   The JOIN USING clause was
overloading this SortGroupBy structure.   With the afore mentioned
reduction of members, the two clauses lost all their commonality.

5.  A bug still exist where, if a function or expression is GROUPed BY,
and an aggregate function does not include a attribute from the
expression or function, the backend crashes.   (or something like
that)   The bug pre-dates this patch.    Example:

    SELECT lower(a) AS lowcase, count(b) FROM foo GROUP BY lowcase;
                 *** BOOM  ***

    --Also when not in target list
    SELECT  count(b) FROM foo GROUP BY lower(a);
                *** BOOM  AGAIN ***

it is now only mergejoin.

Thanks for Vadim for fixes.

From: t-ishii@sra.co.jp

As Bruce mentioned, this is due to the conflict among changes we made.
Included patches should fix the problem(I changed all MB to
MULTIBYTE). Please let me know if you have further problem.

P.S. I did not include pathces to configure and gram.c to save the
file size(configure.in and gram.y modified).

I really hope that I haven't missed anything in this one...

From: t-ishii@sra.co.jp

Attached are patches to enhance the multi-byte support.  (patches are
against 7/18 snapshot)

* determine encoding at initdb/createdb rather than compile time

Now initdb/createdb has an option to specify the encoding. Also, I
modified the syntax of CREATE DATABASE to accept encoding option. See
README.mb for more details.

For this purpose I have added new column "encoding" to pg_database.
Also pg_attribute and pg_class are changed to catch up the
modification to pg_database.  Actually I haved added pg_database_mb.h,
pg_attribute_mb.h and pg_class_mb.h. These are used only when MB is
enabled. The reason having separate files is I couldn't find a way to
use ifdef or whatever in those files. I have to admit it looks
ugly. No way.

* support for PGCLIENTENCODING when issuing COPY command

commands/copy.c modified.

* support for SQL92 syntax "SET NAMES"

See gram.y.

* support for LATIN2-5
* add UNICODE regression test case
* new test suite for MB

New directory test/mb added.

* clean up source files

Basic idea is to have MB's own subdirectory for easier maintenance.
These are include/mb and backend/utils/mb.

members to be clearer.  Fix cost computation for these.

    below  is  the patch to have views to override the permission
    checks for the accessed tables. Now we can do the following:

    CREATE VIEW db_user AS SELECT
         usename,
         usesysid,
         usecreatedb,
         usetrace,
         usecatupd,
         '**********'::text as passwd,
         valuntil
        FROM pg_user;

    REVOKE ALL ON pg_user FROM public;
    REVOKE ALL ON db_user FROM public;
    GRANT SELECT ON db_user TO public;

New PARAM_EXEC type.