1996-07-09 08:22:35 +02:00
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|
/*-------------------------------------------------------------------------
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*
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1999-02-14 00:22:53 +01:00
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* rewriteManip.c
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1996-07-09 08:22:35 +02:00
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*
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2000-01-26 06:58:53 +01:00
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* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
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* Portions Copyright (c) 1994, Regents of the University of California
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1996-07-09 08:22:35 +02:00
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*
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*
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* IDENTIFICATION
|
2000-01-27 19:11:50 +01:00
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* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteManip.c,v 1.44 2000/01/27 18:11:37 tgl Exp $
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1996-07-09 08:22:35 +02:00
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*
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|
*-------------------------------------------------------------------------
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|
*/
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|
#include "postgres.h"
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#include "optimizer/clauses.h"
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2000-01-27 19:11:50 +01:00
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|
#include "optimizer/tlist.h"
|
1999-07-16 07:00:38 +02:00
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|
#include "parser/parsetree.h"
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1999-08-21 05:49:17 +02:00
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#include "parser/parse_clause.h"
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1999-07-16 07:00:38 +02:00
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#include "rewrite/rewriteManip.h"
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#include "utils/builtins.h"
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#include "utils/lsyscache.h"
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1996-07-09 08:22:35 +02:00
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1999-10-01 06:08:24 +02:00
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/* macros borrowed from expression_tree_mutator */
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1996-07-09 08:22:35 +02:00
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1999-10-01 06:08:24 +02:00
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#define FLATCOPY(newnode, node, nodetype) \
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( (newnode) = makeNode(nodetype), \
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memcpy((newnode), (node), sizeof(nodetype)) )
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1998-10-21 18:21:29 +02:00
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1999-10-01 06:08:24 +02:00
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#define MUTATE(newfield, oldfield, fieldtype, mutator, context) \
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( (newfield) = (fieldtype) mutator((Node *) (oldfield), (context)) )
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1998-12-14 01:02:17 +01:00
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1999-10-01 06:08:24 +02:00
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/*
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* OffsetVarNodes - adjust Vars when appending one query's RT to another
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*
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* Find all Var nodes in the given tree with varlevelsup == sublevels_up,
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* and increment their varno fields (rangetable indexes) by 'offset'.
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* The varnoold fields are adjusted similarly.
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*
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* NOTE: although this has the form of a walker, we cheat and modify the
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* Var nodes in-place. The given expression tree should have been copied
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* earlier to ensure that no unwanted side-effects occur!
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*/
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1998-12-14 01:02:17 +01:00
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1999-10-01 06:08:24 +02:00
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typedef struct {
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int offset;
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int sublevels_up;
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} OffsetVarNodes_context;
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1998-10-21 18:21:29 +02:00
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1999-10-01 06:08:24 +02:00
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static bool
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OffsetVarNodes_walker(Node *node, OffsetVarNodes_context *context)
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{
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if (node == NULL)
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return false;
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if (IsA(node, Var))
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{
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Var *var = (Var *) node;
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1998-10-21 18:21:29 +02:00
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1999-10-01 06:08:24 +02:00
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if (var->varlevelsup == context->sublevels_up)
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{
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var->varno += context->offset;
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var->varnoold += context->offset;
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}
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return false;
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1996-07-09 08:22:35 +02:00
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}
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1999-10-01 06:08:24 +02:00
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if (IsA(node, SubLink))
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|
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{
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/*
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* Standard expression_tree_walker will not recurse into subselect,
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* but here we must do so.
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*/
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SubLink *sub = (SubLink *) node;
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if (OffsetVarNodes_walker((Node *) (sub->lefthand),
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context))
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return true;
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OffsetVarNodes((Node *) (sub->subselect),
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context->offset,
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context->sublevels_up + 1);
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return false;
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}
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|
if (IsA(node, Query))
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|
|
{
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|
/* Reach here after recursing down into subselect above... */
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|
Query *qry = (Query *) node;
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if (OffsetVarNodes_walker((Node *) (qry->targetList),
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|
context))
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return true;
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|
if (OffsetVarNodes_walker((Node *) (qry->qual),
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|
context))
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|
return true;
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|
|
if (OffsetVarNodes_walker((Node *) (qry->havingQual),
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|
context))
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|
return true;
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return false;
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|
}
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return expression_tree_walker(node, OffsetVarNodes_walker,
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(void *) context);
|
1996-07-09 08:22:35 +02:00
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}
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|
|
void
|
1999-10-01 06:08:24 +02:00
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OffsetVarNodes(Node *node, int offset, int sublevels_up)
|
1996-07-09 08:22:35 +02:00
|
|
|
{
|
1999-10-01 06:08:24 +02:00
|
|
|
OffsetVarNodes_context context;
|
1998-10-21 18:21:29 +02:00
|
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|
1999-10-01 06:08:24 +02:00
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|
context.offset = offset;
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context.sublevels_up = sublevels_up;
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OffsetVarNodes_walker(node, &context);
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|
}
|
1998-12-14 01:02:17 +01:00
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|
1999-10-01 06:08:24 +02:00
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|
|
/*
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|
* ChangeVarNodes - adjust Var nodes for a specific change of RT index
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|
*
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|
* Find all Var nodes in the given tree belonging to a specific relation
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|
* (identified by sublevels_up and rt_index), and change their varno fields
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|
* to 'new_index'. The varnoold fields are changed too.
|
|
|
|
*
|
|
|
|
* NOTE: although this has the form of a walker, we cheat and modify the
|
|
|
|
* Var nodes in-place. The given expression tree should have been copied
|
|
|
|
* earlier to ensure that no unwanted side-effects occur!
|
|
|
|
*/
|
1998-12-14 01:02:17 +01:00
|
|
|
|
1999-10-01 06:08:24 +02:00
|
|
|
typedef struct {
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|
int rt_index;
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|
int new_index;
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|
int sublevels_up;
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|
|
|
} ChangeVarNodes_context;
|
1998-10-21 18:21:29 +02:00
|
|
|
|
1999-10-01 06:08:24 +02:00
|
|
|
static bool
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|
|
|
ChangeVarNodes_walker(Node *node, ChangeVarNodes_context *context)
|
|
|
|
{
|
|
|
|
if (node == NULL)
|
|
|
|
return false;
|
|
|
|
if (IsA(node, Var))
|
|
|
|
{
|
|
|
|
Var *var = (Var *) node;
|
1998-10-21 18:21:29 +02:00
|
|
|
|
1999-10-01 06:08:24 +02:00
|
|
|
if (var->varlevelsup == context->sublevels_up &&
|
|
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|
var->varno == context->rt_index)
|
|
|
|
{
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|
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|
var->varno = context->new_index;
|
|
|
|
var->varnoold = context->new_index;
|
|
|
|
}
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|
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|
return false;
|
|
|
|
}
|
|
|
|
if (IsA(node, SubLink))
|
|
|
|
{
|
|
|
|
/*
|
|
|
|
* Standard expression_tree_walker will not recurse into subselect,
|
|
|
|
* but here we must do so.
|
|
|
|
*/
|
|
|
|
SubLink *sub = (SubLink *) node;
|
|
|
|
|
|
|
|
if (ChangeVarNodes_walker((Node *) (sub->lefthand),
|
|
|
|
context))
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|
return true;
|
|
|
|
ChangeVarNodes((Node *) (sub->subselect),
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|
context->rt_index,
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|
context->new_index,
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|
|
context->sublevels_up + 1);
|
|
|
|
return false;
|
1996-07-09 08:22:35 +02:00
|
|
|
}
|
1999-10-01 06:08:24 +02:00
|
|
|
if (IsA(node, Query))
|
|
|
|
{
|
|
|
|
/* Reach here after recursing down into subselect above... */
|
|
|
|
Query *qry = (Query *) node;
|
|
|
|
|
|
|
|
if (ChangeVarNodes_walker((Node *) (qry->targetList),
|
|
|
|
context))
|
|
|
|
return true;
|
|
|
|
if (ChangeVarNodes_walker((Node *) (qry->qual),
|
|
|
|
context))
|
|
|
|
return true;
|
|
|
|
if (ChangeVarNodes_walker((Node *) (qry->havingQual),
|
|
|
|
context))
|
|
|
|
return true;
|
|
|
|
return false;
|
|
|
|
}
|
|
|
|
return expression_tree_walker(node, ChangeVarNodes_walker,
|
|
|
|
(void *) context);
|
1996-07-09 08:22:35 +02:00
|
|
|
}
|
|
|
|
|
1999-10-01 06:08:24 +02:00
|
|
|
void
|
|
|
|
ChangeVarNodes(Node *node, int rt_index, int new_index, int sublevels_up)
|
|
|
|
{
|
|
|
|
ChangeVarNodes_context context;
|
1998-10-21 18:21:29 +02:00
|
|
|
|
1999-10-01 06:08:24 +02:00
|
|
|
context.rt_index = rt_index;
|
|
|
|
context.new_index = new_index;
|
|
|
|
context.sublevels_up = sublevels_up;
|
|
|
|
ChangeVarNodes_walker(node, &context);
|
|
|
|
}
|
1998-10-21 18:21:29 +02:00
|
|
|
|
1999-10-01 06:08:24 +02:00
|
|
|
/*
|
|
|
|
* Add the given qualifier condition to the query's WHERE clause
|
|
|
|
*/
|
1996-07-09 08:22:35 +02:00
|
|
|
void
|
1997-09-08 23:56:23 +02:00
|
|
|
AddQual(Query *parsetree, Node *qual)
|
1996-07-09 08:22:35 +02:00
|
|
|
{
|
1997-09-08 04:41:22 +02:00
|
|
|
Node *copy,
|
|
|
|
*old;
|
1997-09-07 07:04:48 +02:00
|
|
|
|
|
|
|
if (qual == NULL)
|
|
|
|
return;
|
|
|
|
|
1999-02-08 02:39:46 +01:00
|
|
|
/* INTERSECT want's the original, but we need to copy - Jan */
|
|
|
|
copy = copyObject(qual);
|
Hi!
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
1999-01-18 01:10:17 +01:00
|
|
|
|
1997-09-07 07:04:48 +02:00
|
|
|
old = parsetree->qual;
|
|
|
|
if (old == NULL)
|
|
|
|
parsetree->qual = copy;
|
|
|
|
else
|
1999-10-01 06:08:24 +02:00
|
|
|
parsetree->qual = (Node *) make_andclause(makeList(old, copy, -1));
|
1996-07-09 08:22:35 +02:00
|
|
|
}
|
|
|
|
|
1999-10-01 06:08:24 +02:00
|
|
|
/*
|
|
|
|
* Add the given havingQual to the one already contained in the parsetree
|
|
|
|
* just as AddQual does for the normal 'where' qual
|
|
|
|
*/
|
1998-07-19 07:49:26 +02:00
|
|
|
void
|
|
|
|
AddHavingQual(Query *parsetree, Node *havingQual)
|
|
|
|
{
|
1998-09-01 06:40:42 +02:00
|
|
|
Node *copy,
|
|
|
|
*old;
|
1998-07-19 07:49:26 +02:00
|
|
|
|
|
|
|
if (havingQual == NULL)
|
|
|
|
return;
|
|
|
|
|
1999-02-08 02:39:46 +01:00
|
|
|
/* INTERSECT want's the original, but we need to copy - Jan */
|
|
|
|
copy = copyObject(havingQual);
|
Hi!
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
1999-01-18 01:10:17 +01:00
|
|
|
|
1998-07-19 07:49:26 +02:00
|
|
|
old = parsetree->havingQual;
|
|
|
|
if (old == NULL)
|
|
|
|
parsetree->havingQual = copy;
|
|
|
|
else
|
1999-10-01 06:08:24 +02:00
|
|
|
parsetree->havingQual = (Node *) make_andclause(makeList(old, copy, -1));
|
1998-07-19 07:49:26 +02:00
|
|
|
}
|
|
|
|
|
1999-05-26 14:57:23 +02:00
|
|
|
#ifdef NOT_USED
|
Hi!
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
1999-01-18 01:10:17 +01:00
|
|
|
void
|
|
|
|
AddNotHavingQual(Query *parsetree, Node *havingQual)
|
|
|
|
{
|
1999-10-01 06:08:24 +02:00
|
|
|
Node *notqual;
|
Hi!
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
1999-01-18 01:10:17 +01:00
|
|
|
|
|
|
|
if (havingQual == NULL)
|
|
|
|
return;
|
|
|
|
|
1999-10-01 06:08:24 +02:00
|
|
|
/* Need not copy input qual, because AddHavingQual will... */
|
|
|
|
notqual = (Node *) make_notclause((Expr *) havingQual);
|
Hi!
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
1999-01-18 01:10:17 +01:00
|
|
|
|
1999-10-01 06:08:24 +02:00
|
|
|
AddHavingQual(parsetree, notqual);
|
Hi!
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
1999-01-18 01:10:17 +01:00
|
|
|
}
|
1999-05-26 14:57:23 +02:00
|
|
|
#endif
|
1998-07-19 07:49:26 +02:00
|
|
|
|
1996-07-09 08:22:35 +02:00
|
|
|
void
|
1997-09-08 23:56:23 +02:00
|
|
|
AddNotQual(Query *parsetree, Node *qual)
|
1996-07-09 08:22:35 +02:00
|
|
|
{
|
1999-10-01 06:08:24 +02:00
|
|
|
Node *notqual;
|
1996-07-09 08:22:35 +02:00
|
|
|
|
1997-09-07 07:04:48 +02:00
|
|
|
if (qual == NULL)
|
|
|
|
return;
|
|
|
|
|
1999-10-01 06:08:24 +02:00
|
|
|
/* Need not copy input qual, because AddQual will... */
|
|
|
|
notqual = (Node *) make_notclause((Expr *) qual);
|
1997-09-07 07:04:48 +02:00
|
|
|
|
1999-10-01 06:08:24 +02:00
|
|
|
AddQual(parsetree, notqual);
|
1996-07-09 08:22:35 +02:00
|
|
|
}
|
|
|
|
|
1999-05-12 17:02:39 +02:00
|
|
|
|
1999-08-21 05:49:17 +02:00
|
|
|
/*
|
|
|
|
* Add all expressions used by the given GroupClause list to the
|
|
|
|
* parsetree's targetlist and groupclause list.
|
|
|
|
*
|
|
|
|
* tlist is the old targetlist associated with the input groupclauses.
|
|
|
|
*
|
|
|
|
* XXX shouldn't we be checking to see if there are already matching
|
|
|
|
* entries in parsetree->targetlist?
|
|
|
|
*/
|
1999-05-12 17:02:39 +02:00
|
|
|
void
|
|
|
|
AddGroupClause(Query *parsetree, List *group_by, List *tlist)
|
|
|
|
{
|
1999-05-25 18:15:34 +02:00
|
|
|
List *l;
|
1999-05-12 17:02:39 +02:00
|
|
|
|
1999-05-25 18:15:34 +02:00
|
|
|
foreach(l, group_by)
|
1999-05-12 17:02:39 +02:00
|
|
|
{
|
1999-08-21 05:49:17 +02:00
|
|
|
GroupClause *groupclause = (GroupClause *) copyObject(lfirst(l));
|
2000-01-27 19:11:50 +01:00
|
|
|
TargetEntry *tle = get_sortgroupclause_tle(groupclause, tlist);
|
1999-08-21 05:49:17 +02:00
|
|
|
|
2000-01-27 19:11:50 +01:00
|
|
|
/* copy the groupclause's TLE from the old tlist */
|
|
|
|
tle = (TargetEntry *) copyObject(tle);
|
1999-05-12 17:02:39 +02:00
|
|
|
|
1999-08-21 05:49:17 +02:00
|
|
|
/* The ressortgroupref number in the old tlist might be already
|
|
|
|
* taken in the new tlist, so force assignment of a new number.
|
|
|
|
*/
|
|
|
|
tle->resdom->ressortgroupref = 0;
|
|
|
|
groupclause->tleSortGroupRef =
|
|
|
|
assignSortGroupRef(tle, parsetree->targetList);
|
|
|
|
|
|
|
|
/* Also need to set the resno and mark it resjunk. */
|
|
|
|
tle->resdom->resno = length(parsetree->targetList) + 1;
|
1999-05-12 17:02:39 +02:00
|
|
|
tle->resdom->resjunk = true;
|
|
|
|
|
1999-05-25 18:15:34 +02:00
|
|
|
parsetree->targetList = lappend(parsetree->targetList, tle);
|
1999-05-12 17:02:39 +02:00
|
|
|
parsetree->groupClause = lappend(parsetree->groupClause, groupclause);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
1997-09-08 04:41:22 +02:00
|
|
|
static Node *
|
1996-07-09 08:22:35 +02:00
|
|
|
make_null(Oid type)
|
|
|
|
{
|
1997-09-08 04:41:22 +02:00
|
|
|
Const *c = makeNode(Const);
|
1997-09-07 07:04:48 +02:00
|
|
|
|
|
|
|
c->consttype = type;
|
|
|
|
c->constlen = get_typlen(type);
|
|
|
|
c->constvalue = PointerGetDatum(NULL);
|
|
|
|
c->constisnull = true;
|
|
|
|
c->constbyval = get_typbyval(type);
|
|
|
|
return (Node *) c;
|
1996-07-09 08:22:35 +02:00
|
|
|
}
|
|
|
|
|
1998-10-08 20:30:52 +02:00
|
|
|
#ifdef NOT_USED
|
1996-07-09 08:22:35 +02:00
|
|
|
void
|
1997-09-08 23:56:23 +02:00
|
|
|
FixResdomTypes(List *tlist)
|
1996-07-09 08:22:35 +02:00
|
|
|
{
|
1997-09-08 04:41:22 +02:00
|
|
|
List *i;
|
1996-07-09 08:22:35 +02:00
|
|
|
|
1997-09-07 07:04:48 +02:00
|
|
|
foreach(i, tlist)
|
|
|
|
{
|
1997-09-08 04:41:22 +02:00
|
|
|
TargetEntry *tle = lfirst(i);
|
1996-07-09 08:22:35 +02:00
|
|
|
|
1997-09-07 07:04:48 +02:00
|
|
|
if (nodeTag(tle->expr) == T_Var)
|
|
|
|
{
|
1997-09-08 04:41:22 +02:00
|
|
|
Var *var = (Var *) tle->expr;
|
1996-07-09 08:22:35 +02:00
|
|
|
|
1997-09-07 07:04:48 +02:00
|
|
|
tle->resdom->restype = var->vartype;
|
1998-02-10 05:02:59 +01:00
|
|
|
tle->resdom->restypmod = var->vartypmod;
|
1997-09-07 07:04:48 +02:00
|
|
|
}
|
1996-07-09 08:22:35 +02:00
|
|
|
}
|
|
|
|
}
|
1999-05-25 18:15:34 +02:00
|
|
|
|
1998-10-08 20:30:52 +02:00
|
|
|
#endif
|
1996-07-09 08:22:35 +02:00
|
|
|
|
1999-10-01 06:08:24 +02:00
|
|
|
/* Find a targetlist entry by resno */
|
1997-09-08 04:41:22 +02:00
|
|
|
static Node *
|
1997-09-08 23:56:23 +02:00
|
|
|
FindMatchingNew(List *tlist, int attno)
|
1996-07-09 08:22:35 +02:00
|
|
|
{
|
1997-09-08 04:41:22 +02:00
|
|
|
List *i;
|
1996-07-09 08:22:35 +02:00
|
|
|
|
1997-09-07 07:04:48 +02:00
|
|
|
foreach(i, tlist)
|
|
|
|
{
|
1997-09-08 04:41:22 +02:00
|
|
|
TargetEntry *tle = lfirst(i);
|
1997-09-07 07:04:48 +02:00
|
|
|
|
|
|
|
if (tle->resdom->resno == attno)
|
1998-09-01 05:29:17 +02:00
|
|
|
return tle->expr;
|
1996-07-09 08:22:35 +02:00
|
|
|
}
|
1997-09-07 07:04:48 +02:00
|
|
|
return NULL;
|
1996-07-09 08:22:35 +02:00
|
|
|
}
|
|
|
|
|
1999-10-01 06:08:24 +02:00
|
|
|
/* Find a targetlist entry by resname */
|
1997-09-08 04:41:22 +02:00
|
|
|
static Node *
|
1997-09-08 23:56:23 +02:00
|
|
|
FindMatchingTLEntry(List *tlist, char *e_attname)
|
1996-07-09 08:22:35 +02:00
|
|
|
{
|
1997-09-08 04:41:22 +02:00
|
|
|
List *i;
|
1997-09-07 07:04:48 +02:00
|
|
|
|
|
|
|
foreach(i, tlist)
|
|
|
|
{
|
1997-09-08 04:41:22 +02:00
|
|
|
TargetEntry *tle = lfirst(i);
|
|
|
|
char *resname;
|
1997-09-07 07:04:48 +02:00
|
|
|
|
|
|
|
resname = tle->resdom->resname;
|
|
|
|
if (!strcmp(e_attname, resname))
|
1998-09-01 05:29:17 +02:00
|
|
|
return tle->expr;
|
1997-09-07 07:04:48 +02:00
|
|
|
}
|
|
|
|
return NULL;
|
1996-07-09 08:22:35 +02:00
|
|
|
}
|
|
|
|
|
1998-01-21 05:24:46 +01:00
|
|
|
|
1999-10-01 06:08:24 +02:00
|
|
|
/*
|
|
|
|
* ResolveNew - replace Vars with corresponding items from a targetlist
|
|
|
|
*
|
|
|
|
* Vars matching info->new_varno and sublevels_up are replaced by the
|
|
|
|
* entry with matching resno from targetlist, if there is one.
|
|
|
|
*/
|
1996-07-09 08:22:35 +02:00
|
|
|
|
1999-10-01 06:08:24 +02:00
|
|
|
typedef struct {
|
|
|
|
RewriteInfo *info;
|
|
|
|
List *targetlist;
|
|
|
|
int sublevels_up;
|
|
|
|
} ResolveNew_context;
|
1996-07-09 08:22:35 +02:00
|
|
|
|
1999-10-01 06:08:24 +02:00
|
|
|
static Node *
|
|
|
|
ResolveNew_mutator(Node *node, ResolveNew_context *context)
|
1996-07-09 08:22:35 +02:00
|
|
|
{
|
1997-09-07 07:04:48 +02:00
|
|
|
if (node == NULL)
|
1999-10-01 06:08:24 +02:00
|
|
|
return NULL;
|
|
|
|
if (IsA(node, Var))
|
1996-07-09 08:22:35 +02:00
|
|
|
{
|
1999-10-01 06:08:24 +02:00
|
|
|
Var *var = (Var *) node;
|
|
|
|
int this_varno = (int) var->varno;
|
|
|
|
int this_varlevelsup = (int) var->varlevelsup;
|
1998-01-04 05:31:43 +01:00
|
|
|
|
1999-10-01 06:08:24 +02:00
|
|
|
if (this_varno == context->info->new_varno &&
|
|
|
|
this_varlevelsup == context->sublevels_up)
|
|
|
|
{
|
|
|
|
Node *n = FindMatchingNew(context->targetlist,
|
|
|
|
var->varattno);
|
1998-10-02 18:28:04 +02:00
|
|
|
|
1999-10-01 06:08:24 +02:00
|
|
|
if (n == NULL)
|
1997-09-07 07:04:48 +02:00
|
|
|
{
|
1999-10-01 06:08:24 +02:00
|
|
|
if (context->info->event == CMD_UPDATE)
|
1997-09-07 07:04:48 +02:00
|
|
|
{
|
1999-10-01 06:08:24 +02:00
|
|
|
/* For update, just change unmatched var's varno */
|
|
|
|
n = copyObject(node);
|
|
|
|
((Var *) n)->varno = context->info->current_varno;
|
|
|
|
((Var *) n)->varnoold = context->info->current_varno;
|
|
|
|
return n;
|
|
|
|
}
|
|
|
|
else
|
|
|
|
{
|
|
|
|
/* Otherwise replace unmatched var with a null */
|
|
|
|
return make_null(var->vartype);
|
1997-09-07 07:04:48 +02:00
|
|
|
}
|
1998-01-21 05:24:46 +01:00
|
|
|
}
|
1999-10-01 06:08:24 +02:00
|
|
|
else
|
1998-01-21 05:24:46 +01:00
|
|
|
{
|
1999-10-01 06:08:24 +02:00
|
|
|
/* Make a copy of the tlist item to return */
|
|
|
|
n = copyObject(n);
|
|
|
|
if (IsA(n, Var))
|
1998-01-21 05:24:46 +01:00
|
|
|
{
|
1999-10-01 06:08:24 +02:00
|
|
|
((Var *) n)->varlevelsup = this_varlevelsup;
|
1997-09-07 07:04:48 +02:00
|
|
|
}
|
1999-10-01 06:08:24 +02:00
|
|
|
/* XXX what to do if tlist item is NOT a var?
|
|
|
|
* Should we be using something like apply_RIR_adjust_sublevel?
|
|
|
|
*/
|
|
|
|
return n;
|
1997-09-07 07:04:48 +02:00
|
|
|
}
|
1999-10-01 06:08:24 +02:00
|
|
|
}
|
|
|
|
/* otherwise fall through to copy the var normally */
|
|
|
|
}
|
|
|
|
/*
|
|
|
|
* Since expression_tree_mutator won't touch subselects, we have to
|
|
|
|
* handle them specially.
|
|
|
|
*/
|
|
|
|
if (IsA(node, SubLink))
|
|
|
|
{
|
|
|
|
SubLink *sublink = (SubLink *) node;
|
|
|
|
SubLink *newnode;
|
|
|
|
|
|
|
|
FLATCOPY(newnode, sublink, SubLink);
|
|
|
|
MUTATE(newnode->lefthand, sublink->lefthand, List *,
|
|
|
|
ResolveNew_mutator, context);
|
|
|
|
context->sublevels_up++;
|
|
|
|
MUTATE(newnode->subselect, sublink->subselect, Node *,
|
|
|
|
ResolveNew_mutator, context);
|
|
|
|
context->sublevels_up--;
|
|
|
|
return (Node *) newnode;
|
|
|
|
}
|
|
|
|
if (IsA(node, Query))
|
|
|
|
{
|
|
|
|
Query *query = (Query *) node;
|
|
|
|
Query *newnode;
|
1998-01-21 05:24:46 +01:00
|
|
|
|
1999-10-01 06:08:24 +02:00
|
|
|
/*
|
|
|
|
* XXX original code for ResolveNew only recursed into qual field
|
|
|
|
* of subquery. I'm assuming that was an oversight ... tgl 9/99
|
|
|
|
*/
|
|
|
|
|
|
|
|
FLATCOPY(newnode, query, Query);
|
|
|
|
MUTATE(newnode->targetList, query->targetList, List *,
|
|
|
|
ResolveNew_mutator, context);
|
|
|
|
MUTATE(newnode->qual, query->qual, Node *,
|
|
|
|
ResolveNew_mutator, context);
|
|
|
|
MUTATE(newnode->havingQual, query->havingQual, Node *,
|
|
|
|
ResolveNew_mutator, context);
|
|
|
|
return (Node *) newnode;
|
1996-07-09 08:22:35 +02:00
|
|
|
}
|
1999-10-01 06:08:24 +02:00
|
|
|
return expression_tree_mutator(node, ResolveNew_mutator,
|
|
|
|
(void *) context);
|
|
|
|
}
|
|
|
|
|
|
|
|
static Node *
|
|
|
|
ResolveNew(Node *node, RewriteInfo *info, List *targetlist,
|
|
|
|
int sublevels_up)
|
|
|
|
{
|
|
|
|
ResolveNew_context context;
|
|
|
|
|
|
|
|
context.info = info;
|
|
|
|
context.targetlist = targetlist;
|
|
|
|
context.sublevels_up = sublevels_up;
|
|
|
|
|
|
|
|
return ResolveNew_mutator(node, &context);
|
|
|
|
}
|
|
|
|
|
|
|
|
void
|
|
|
|
FixNew(RewriteInfo *info, Query *parsetree)
|
|
|
|
{
|
|
|
|
info->rule_action->targetList = (List *)
|
|
|
|
ResolveNew((Node *) info->rule_action->targetList,
|
|
|
|
info, parsetree->targetList, 0);
|
|
|
|
info->rule_action->qual = ResolveNew(info->rule_action->qual,
|
|
|
|
info, parsetree->targetList, 0);
|
|
|
|
/* XXX original code didn't fix havingQual; presumably an oversight? */
|
|
|
|
info->rule_action->havingQual = ResolveNew(info->rule_action->havingQual,
|
|
|
|
info, parsetree->targetList, 0);
|
1996-07-09 08:22:35 +02:00
|
|
|
}
|
|
|
|
|
1997-09-07 07:04:48 +02:00
|
|
|
/*
|
1999-10-01 06:08:24 +02:00
|
|
|
* HandleRIRAttributeRule
|
|
|
|
* Replace Vars matching a given RT index with copies of TL expressions.
|
|
|
|
*
|
1996-07-09 08:22:35 +02:00
|
|
|
* Handles 'on retrieve to relation.attribute
|
1997-09-07 07:04:48 +02:00
|
|
|
* do instead retrieve (attribute = expression) w/qual'
|
1999-10-01 06:08:24 +02:00
|
|
|
*
|
|
|
|
* XXX Why is this not unified with apply_RIR_view()?
|
1996-07-09 08:22:35 +02:00
|
|
|
*/
|
1998-02-26 05:46:47 +01:00
|
|
|
|
1999-10-01 06:08:24 +02:00
|
|
|
typedef struct {
|
|
|
|
List *rtable;
|
|
|
|
List *targetlist;
|
|
|
|
int rt_index;
|
|
|
|
int attr_num;
|
|
|
|
int *modified;
|
|
|
|
int *badsql;
|
|
|
|
int sublevels_up;
|
|
|
|
} HandleRIRAttributeRule_context;
|
1996-07-09 08:22:35 +02:00
|
|
|
|
1999-10-01 06:08:24 +02:00
|
|
|
static Node *
|
|
|
|
HandleRIRAttributeRule_mutator(Node *node,
|
|
|
|
HandleRIRAttributeRule_context *context)
|
1996-07-09 08:22:35 +02:00
|
|
|
{
|
1997-09-07 07:04:48 +02:00
|
|
|
if (node == NULL)
|
1999-10-01 06:08:24 +02:00
|
|
|
return NULL;
|
|
|
|
if (IsA(node, Var))
|
1996-07-09 08:22:35 +02:00
|
|
|
{
|
1999-10-01 06:08:24 +02:00
|
|
|
Var *var = (Var *) node;
|
|
|
|
int this_varno = var->varno;
|
|
|
|
int this_varattno = var->varattno;
|
|
|
|
int this_varlevelsup = var->varlevelsup;
|
|
|
|
|
|
|
|
if (this_varno == context->rt_index &&
|
|
|
|
this_varattno == context->attr_num &&
|
|
|
|
this_varlevelsup == context->sublevels_up)
|
|
|
|
{
|
|
|
|
if (var->vartype == 32)
|
|
|
|
{ /* HACK: disallow SET variables */
|
|
|
|
*context->modified = TRUE;
|
|
|
|
*context->badsql = TRUE;
|
|
|
|
return make_null(var->vartype);
|
|
|
|
}
|
|
|
|
else
|
|
|
|
{
|
|
|
|
NameData name_to_look_for;
|
|
|
|
|
1999-11-08 00:08:36 +01:00
|
|
|
NameStr(name_to_look_for)[0] = '\0';
|
1999-10-01 06:08:24 +02:00
|
|
|
namestrcpy(&name_to_look_for,
|
|
|
|
(char *) get_attname(getrelid(this_varno,
|
|
|
|
context->rtable),
|
|
|
|
this_varattno));
|
1999-11-08 00:08:36 +01:00
|
|
|
if (NameStr(name_to_look_for)[0])
|
1998-09-01 06:40:42 +02:00
|
|
|
{
|
1999-10-01 06:08:24 +02:00
|
|
|
Node *n;
|
|
|
|
|
|
|
|
*context->modified = TRUE;
|
|
|
|
n = FindMatchingTLEntry(context->targetlist,
|
|
|
|
(char *) &name_to_look_for);
|
1998-09-01 06:40:42 +02:00
|
|
|
if (n == NULL)
|
1999-10-01 06:08:24 +02:00
|
|
|
return make_null(var->vartype);
|
1998-09-01 06:40:42 +02:00
|
|
|
else
|
1999-10-01 06:08:24 +02:00
|
|
|
return copyObject(n);
|
1998-01-21 05:24:46 +01:00
|
|
|
}
|
|
|
|
}
|
1999-10-01 06:08:24 +02:00
|
|
|
}
|
|
|
|
/* otherwise fall through to copy the var normally */
|
|
|
|
}
|
|
|
|
/*
|
|
|
|
* Since expression_tree_mutator won't touch subselects, we have to
|
|
|
|
* handle them specially.
|
|
|
|
*/
|
|
|
|
if (IsA(node, SubLink))
|
|
|
|
{
|
|
|
|
SubLink *sublink = (SubLink *) node;
|
|
|
|
SubLink *newnode;
|
|
|
|
|
|
|
|
FLATCOPY(newnode, sublink, SubLink);
|
|
|
|
MUTATE(newnode->lefthand, sublink->lefthand, List *,
|
|
|
|
HandleRIRAttributeRule_mutator, context);
|
|
|
|
context->sublevels_up++;
|
|
|
|
MUTATE(newnode->subselect, sublink->subselect, Node *,
|
|
|
|
HandleRIRAttributeRule_mutator, context);
|
|
|
|
context->sublevels_up--;
|
|
|
|
return (Node *) newnode;
|
|
|
|
}
|
|
|
|
if (IsA(node, Query))
|
|
|
|
{
|
|
|
|
Query *query = (Query *) node;
|
|
|
|
Query *newnode;
|
Hi!
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
1999-01-18 01:10:17 +01:00
|
|
|
|
1999-10-01 06:08:24 +02:00
|
|
|
/*
|
|
|
|
* XXX original code for HandleRIRAttributeRule only recursed into
|
|
|
|
* qual field of subquery. I'm assuming that was an oversight ...
|
|
|
|
*/
|
Hi!
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
1999-01-18 01:10:17 +01:00
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1999-10-01 06:08:24 +02:00
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FLATCOPY(newnode, query, Query);
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MUTATE(newnode->targetList, query->targetList, List *,
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HandleRIRAttributeRule_mutator, context);
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MUTATE(newnode->qual, query->qual, Node *,
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HandleRIRAttributeRule_mutator, context);
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MUTATE(newnode->havingQual, query->havingQual, Node *,
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HandleRIRAttributeRule_mutator, context);
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return (Node *) newnode;
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1996-07-09 08:22:35 +02:00
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}
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1999-10-01 06:08:24 +02:00
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return expression_tree_mutator(node, HandleRIRAttributeRule_mutator,
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(void *) context);
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1996-07-09 08:22:35 +02:00
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}
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void
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1999-10-01 06:08:24 +02:00
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HandleRIRAttributeRule(Query *parsetree,
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List *rtable,
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List *targetlist,
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int rt_index,
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int attr_num,
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int *modified,
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int *badsql)
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1996-07-09 08:22:35 +02:00
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{
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1999-10-01 06:08:24 +02:00
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HandleRIRAttributeRule_context context;
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context.rtable = rtable;
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context.targetlist = targetlist;
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context.rt_index = rt_index;
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context.attr_num = attr_num;
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context.modified = modified;
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context.badsql = badsql;
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context.sublevels_up = 0;
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parsetree->targetList = (List *)
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HandleRIRAttributeRule_mutator((Node *) parsetree->targetList,
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&context);
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parsetree->qual = HandleRIRAttributeRule_mutator(parsetree->qual,
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&context);
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/* XXX original code did not fix havingQual ... oversight? */
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parsetree->havingQual = HandleRIRAttributeRule_mutator(parsetree->havingQual,
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&context);
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1996-07-09 08:22:35 +02:00
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}
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