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postgres/src/backend/rewrite/rewriteManip.c
Tom Lane 6eeb95f0f5 Restructure representation of join alias variables. An explicit JOIN 
now has an RTE of its own, and references to its outputs now are Vars
referencing the JOIN RTE, rather than CASE-expressions.  This allows
reverse-listing in ruleutils.c to use the correct alias easily, rather
than painfully reverse-engineering the alias namespace as it used to do.
Also, nested FULL JOINs work correctly, because the result of the inner
joins are simple Vars that the planner can cope with.  This fixes a bug
reported a couple times now, notably by Tatsuo on 18-Nov-01.  The alias
Vars are expanded into COALESCE expressions where needed at the very end
of planning, rather than during parsing.
Also, beginnings of support for showing plan qualifier expressions in
EXPLAIN.  There are probably still cases that need work.
initdb forced due to change of stored-rule representation.
2002-03-12 00:52:10 +00:00

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/*-------------------------------------------------------------------------
*
* rewriteManip.c
*
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteManip.c,v 1.62 2002/03/12 00:51:58 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "nodes/makefuncs.h"
#include "optimizer/clauses.h"
#include "optimizer/tlist.h"
#include "parser/parsetree.h"
#include "parser/parse_clause.h"
#include "rewrite/rewriteManip.h"
#include "utils/lsyscache.h"
/* macros borrowed from expression_tree_mutator */
#define FLATCOPY(newnode, node, nodetype) \
( (newnode) = makeNode(nodetype), \
memcpy((newnode), (node), sizeof(nodetype)) )
#define MUTATE(newfield, oldfield, fieldtype, mutator, context) \
( (newfield) = (fieldtype) mutator((Node *) (oldfield), (context)) )
static bool checkExprHasAggs_walker(Node *node, void *context);
static bool checkExprHasSubLink_walker(Node *node, void *context);
/*
* checkExprHasAggs -
* Queries marked hasAggs might not have them any longer after
* rewriting. Check it.
*/
bool
checkExprHasAggs(Node *node)
{
/*
* If a Query is passed, examine it --- but we will not recurse into
* sub-Queries.
*/
if (node && IsA(node, Query))
return query_tree_walker((Query *) node, checkExprHasAggs_walker,
NULL, false);
else
return checkExprHasAggs_walker(node, NULL);
}
static bool
checkExprHasAggs_walker(Node *node, void *context)
{
if (node == NULL)
return false;
if (IsA(node, Aggref))
return true; /* abort the tree traversal and return
* true */
return expression_tree_walker(node, checkExprHasAggs_walker, context);
}
/*
* checkExprHasSubLink -
* Queries marked hasSubLinks might not have them any longer after
* rewriting. Check it.
*/
bool
checkExprHasSubLink(Node *node)
{
/*
* If a Query is passed, examine it --- but we will not recurse into
* sub-Queries.
*/
if (node && IsA(node, Query))
return query_tree_walker((Query *) node, checkExprHasSubLink_walker,
NULL, false);
else
return checkExprHasSubLink_walker(node, NULL);
}
static bool
checkExprHasSubLink_walker(Node *node, void *context)
{
if (node == NULL)
return false;
if (IsA(node, SubLink))
return true; /* abort the tree traversal and return
* true */
return expression_tree_walker(node, checkExprHasSubLink_walker, context);
}
/*
* OffsetVarNodes - adjust Vars when appending one query's RT to another
*
* Find all Var nodes in the given tree with varlevelsup == sublevels_up,
* and increment their varno fields (rangetable indexes) by 'offset'.
* The varnoold fields are adjusted similarly. Also, RangeTblRef and
* JoinExpr nodes in join trees and setOp trees are adjusted.
*
* NOTE: although this has the form of a walker, we cheat and modify the
* nodes in-place. The given expression tree should have been copied
* earlier to ensure that no unwanted side-effects occur!
*/
typedef struct
{
int offset;
int sublevels_up;
} OffsetVarNodes_context;
static bool
OffsetVarNodes_walker(Node *node, OffsetVarNodes_context *context)
{
if (node == NULL)
return false;
if (IsA(node, Var))
{
Var *var = (Var *) node;
if (var->varlevelsup == context->sublevels_up)
{
var->varno += context->offset;
var->varnoold += context->offset;
}
return false;
}
if (IsA(node, RangeTblRef))
{
RangeTblRef *rtr = (RangeTblRef *) node;
if (context->sublevels_up == 0)
rtr->rtindex += context->offset;
/* the subquery itself is visited separately */
return false;
}
if (IsA(node, JoinExpr))
{
JoinExpr *j = (JoinExpr *) node;
if (context->sublevels_up == 0)
j->rtindex += context->offset;
/* fall through to examine children */
}
if (IsA(node, Query))
{
/* Recurse into subselects */
bool result;
context->sublevels_up++;
result = query_tree_walker((Query *) node, OffsetVarNodes_walker,
(void *) context, true);
context->sublevels_up--;
return result;
}
return expression_tree_walker(node, OffsetVarNodes_walker,
(void *) context);
}
void
OffsetVarNodes(Node *node, int offset, int sublevels_up)
{
OffsetVarNodes_context context;
context.offset = offset;
context.sublevels_up = sublevels_up;
/*
* Must be prepared to start with a Query or a bare expression tree;
* if it's a Query, go straight to query_tree_walker to make sure that
* sublevels_up doesn't get incremented prematurely.
*/
if (node && IsA(node, Query))
{
Query *qry = (Query *) node;
List *l;
/*
* If we are starting at a Query, and sublevels_up is zero, then
* we must also fix rangetable indexes in the Query itself ---
* namely resultRelation and rowMarks entries. sublevels_up
* cannot be zero when recursing into a subquery, so there's no
* need to have the same logic inside OffsetVarNodes_walker.
*/
if (sublevels_up == 0)
{
if (qry->resultRelation)
qry->resultRelation += offset;
foreach(l, qry->rowMarks)
lfirsti(l) += offset;
}
query_tree_walker(qry, OffsetVarNodes_walker,
(void *) &context, true);
}
else
OffsetVarNodes_walker(node, &context);
}
/*
* ChangeVarNodes - adjust Var nodes for a specific change of RT index
*
* Find all Var nodes in the given tree belonging to a specific relation
* (identified by sublevels_up and rt_index), and change their varno fields
* to 'new_index'. The varnoold fields are changed too. Also, RangeTblRef
* and JoinExpr nodes in join trees and setOp trees are adjusted.
*
* NOTE: although this has the form of a walker, we cheat and modify the
* nodes in-place. The given expression tree should have been copied
* earlier to ensure that no unwanted side-effects occur!
*/
typedef struct
{
int rt_index;
int new_index;
int sublevels_up;
} ChangeVarNodes_context;
static bool
ChangeVarNodes_walker(Node *node, ChangeVarNodes_context *context)
{
if (node == NULL)
return false;
if (IsA(node, Var))
{
Var *var = (Var *) node;
if (var->varlevelsup == context->sublevels_up &&
var->varno == context->rt_index)
{
var->varno = context->new_index;
var->varnoold = context->new_index;
}
return false;
}
if (IsA(node, RangeTblRef))
{
RangeTblRef *rtr = (RangeTblRef *) node;
if (context->sublevels_up == 0 &&
rtr->rtindex == context->rt_index)
rtr->rtindex = context->new_index;
/* the subquery itself is visited separately */
return false;
}
if (IsA(node, JoinExpr))
{
JoinExpr *j = (JoinExpr *) node;
if (context->sublevels_up == 0 &&
j->rtindex == context->rt_index)
j->rtindex = context->new_index;
/* fall through to examine children */
}
if (IsA(node, Query))
{
/* Recurse into subselects */
bool result;
context->sublevels_up++;
result = query_tree_walker((Query *) node, ChangeVarNodes_walker,
(void *) context, true);
context->sublevels_up--;
return result;
}
return expression_tree_walker(node, ChangeVarNodes_walker,
(void *) context);
}
void
ChangeVarNodes(Node *node, int rt_index, int new_index, int sublevels_up)
{
ChangeVarNodes_context context;
context.rt_index = rt_index;
context.new_index = new_index;
context.sublevels_up = sublevels_up;
/*
* Must be prepared to start with a Query or a bare expression tree;
* if it's a Query, go straight to query_tree_walker to make sure that
* sublevels_up doesn't get incremented prematurely.
*/
if (node && IsA(node, Query))
{
Query *qry = (Query *) node;
List *l;
/*
* If we are starting at a Query, and sublevels_up is zero, then
* we must also fix rangetable indexes in the Query itself ---
* namely resultRelation and rowMarks entries. sublevels_up
* cannot be zero when recursing into a subquery, so there's no
* need to have the same logic inside ChangeVarNodes_walker.
*/
if (sublevels_up == 0)
{
if (qry->resultRelation == rt_index)
qry->resultRelation = new_index;
foreach(l, qry->rowMarks)
{
if (lfirsti(l) == rt_index)
lfirsti(l) = new_index;
}
}
query_tree_walker(qry, ChangeVarNodes_walker,
(void *) &context, true);
}
else
ChangeVarNodes_walker(node, &context);
}
/*
* IncrementVarSublevelsUp - adjust Var nodes when pushing them down in tree
*
* Find all Var nodes in the given tree having varlevelsup >= min_sublevels_up,
* and add delta_sublevels_up to their varlevelsup value. This is needed when
* an expression that's correct for some nesting level is inserted into a
* subquery. Ordinarily the initial call has min_sublevels_up == 0 so that
* all Vars are affected. The point of min_sublevels_up is that we can
* increment it when we recurse into a sublink, so that local variables in
* that sublink are not affected, only outer references to vars that belong
* to the expression's original query level or parents thereof.
*
* 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!
*/
typedef struct
{
int delta_sublevels_up;
int min_sublevels_up;
} IncrementVarSublevelsUp_context;
static bool
IncrementVarSublevelsUp_walker(Node *node,
IncrementVarSublevelsUp_context *context)
{
if (node == NULL)
return false;
if (IsA(node, Var))
{
Var *var = (Var *) node;
if (var->varlevelsup >= context->min_sublevels_up)
var->varlevelsup += context->delta_sublevels_up;
return false;
}
if (IsA(node, Query))
{
/* Recurse into subselects */
bool result;
context->min_sublevels_up++;
result = query_tree_walker((Query *) node,
IncrementVarSublevelsUp_walker,
(void *) context, true);
context->min_sublevels_up--;
return result;
}
return expression_tree_walker(node, IncrementVarSublevelsUp_walker,
(void *) context);
}
void
IncrementVarSublevelsUp(Node *node, int delta_sublevels_up,
int min_sublevels_up)
{
IncrementVarSublevelsUp_context context;
context.delta_sublevels_up = delta_sublevels_up;
context.min_sublevels_up = min_sublevels_up;
/*
* Must be prepared to start with a Query or a bare expression tree;
* if it's a Query, go straight to query_tree_walker to make sure that
* sublevels_up doesn't get incremented prematurely.
*/
if (node && IsA(node, Query))
query_tree_walker((Query *) node, IncrementVarSublevelsUp_walker,
(void *) &context, true);
else
IncrementVarSublevelsUp_walker(node, &context);
}
/*
* rangeTableEntry_used - detect whether an RTE is referenced somewhere
* in var nodes or join or setOp trees of a query or expression.
*/
typedef struct
{
int rt_index;
int sublevels_up;
} rangeTableEntry_used_context;
static bool
rangeTableEntry_used_walker(Node *node,
rangeTableEntry_used_context *context)
{
if (node == NULL)
return false;
if (IsA(node, Var))
{
Var *var = (Var *) node;
if (var->varlevelsup == context->sublevels_up &&
var->varno == context->rt_index)
return true;
return false;
}
if (IsA(node, RangeTblRef))
{
RangeTblRef *rtr = (RangeTblRef *) node;
if (rtr->rtindex == context->rt_index &&
context->sublevels_up == 0)
return true;
/* the subquery itself is visited separately */
return false;
}
if (IsA(node, JoinExpr))
{
JoinExpr *j = (JoinExpr *) node;
if (j->rtindex == context->rt_index &&
context->sublevels_up == 0)
return true;
/* fall through to examine children */
}
if (IsA(node, Query))
{
/* Recurse into subselects */
bool result;
context->sublevels_up++;
result = query_tree_walker((Query *) node, rangeTableEntry_used_walker,
(void *) context, true);
context->sublevels_up--;
return result;
}
return expression_tree_walker(node, rangeTableEntry_used_walker,
(void *) context);
}
bool
rangeTableEntry_used(Node *node, int rt_index, int sublevels_up)
{
rangeTableEntry_used_context context;
context.rt_index = rt_index;
context.sublevels_up = sublevels_up;
/*
* Must be prepared to start with a Query or a bare expression tree;
* if it's a Query, go straight to query_tree_walker to make sure that
* sublevels_up doesn't get incremented prematurely.
*/
if (node && IsA(node, Query))
return query_tree_walker((Query *) node, rangeTableEntry_used_walker,
(void *) &context, true);
else
return rangeTableEntry_used_walker(node, &context);
}
/*
* attribute_used -
* Check if a specific attribute number of a RTE is used
* somewhere in the query or expression.
*/
typedef struct
{
int rt_index;
int attno;
int sublevels_up;
} attribute_used_context;
static bool
attribute_used_walker(Node *node,
attribute_used_context *context)
{
if (node == NULL)
return false;
if (IsA(node, Var))
{
Var *var = (Var *) node;
if (var->varlevelsup == context->sublevels_up &&
var->varno == context->rt_index &&
var->varattno == context->attno)
return true;
return false;
}
if (IsA(node, Query))
{
/* Recurse into subselects */
bool result;
context->sublevels_up++;
result = query_tree_walker((Query *) node, attribute_used_walker,
(void *) context, true);
context->sublevels_up--;
return result;
}
return expression_tree_walker(node, attribute_used_walker,
(void *) context);
}
bool
attribute_used(Node *node, int rt_index, int attno, int sublevels_up)
{
attribute_used_context context;
context.rt_index = rt_index;
context.attno = attno;
context.sublevels_up = sublevels_up;
/*
* Must be prepared to start with a Query or a bare expression tree;
* if it's a Query, go straight to query_tree_walker to make sure that
* sublevels_up doesn't get incremented prematurely.
*/
if (node && IsA(node, Query))
return query_tree_walker((Query *) node, attribute_used_walker,
(void *) &context, true);
else
return attribute_used_walker(node, &context);
}
/*
* If the given Query is an INSERT ... SELECT construct, extract and
* return the sub-Query node that represents the SELECT part. Otherwise
* return the given Query.
*
* If subquery_ptr is not NULL, then *subquery_ptr is set to the location
* of the link to the SELECT subquery inside parsetree, or NULL if not an
* INSERT ... SELECT.
*
* This is a hack needed because transformations on INSERT ... SELECTs that
* appear in rule actions should be applied to the source SELECT, not to the
* INSERT part. Perhaps this can be cleaned up with redesigned querytrees.
*/
Query *
getInsertSelectQuery(Query *parsetree, Query ***subquery_ptr)
{
Query *selectquery;
RangeTblEntry *selectrte;
RangeTblRef *rtr;
if (subquery_ptr)
*subquery_ptr = NULL;
if (parsetree == NULL)
return parsetree;
if (parsetree->commandType != CMD_INSERT)
return parsetree;
/*
* Currently, this is ONLY applied to rule-action queries, and so we
* expect to find the *OLD* and *NEW* placeholder entries in the given
* query. If they're not there, it must be an INSERT/SELECT in which
* they've been pushed down to the SELECT.
*/
if (length(parsetree->rtable) >= 2 &&
strcmp(rt_fetch(PRS2_OLD_VARNO, parsetree->rtable)->eref->relname,
"*OLD*") == 0 &&
strcmp(rt_fetch(PRS2_NEW_VARNO, parsetree->rtable)->eref->relname,
"*NEW*") == 0)
return parsetree;
Assert(parsetree->jointree && IsA(parsetree->jointree, FromExpr));
if (length(parsetree->jointree->fromlist) != 1)
elog(ERROR, "getInsertSelectQuery: expected to find SELECT subquery");
rtr = (RangeTblRef *) lfirst(parsetree->jointree->fromlist);
Assert(IsA(rtr, RangeTblRef));
selectrte = rt_fetch(rtr->rtindex, parsetree->rtable);
selectquery = selectrte->subquery;
if (!(selectquery && IsA(selectquery, Query) &&
selectquery->commandType == CMD_SELECT))
elog(ERROR, "getInsertSelectQuery: expected to find SELECT subquery");
if (length(selectquery->rtable) >= 2 &&
strcmp(rt_fetch(PRS2_OLD_VARNO, selectquery->rtable)->eref->relname,
"*OLD*") == 0 &&
strcmp(rt_fetch(PRS2_NEW_VARNO, selectquery->rtable)->eref->relname,
"*NEW*") == 0)
{
if (subquery_ptr)
*subquery_ptr = &(selectrte->subquery);
return selectquery;
}
elog(ERROR, "getInsertSelectQuery: can't find rule placeholders");
return NULL; /* not reached */
}
/*
* Add the given qualifier condition to the query's WHERE clause
*/
void
AddQual(Query *parsetree, Node *qual)
{
Node *copy;
if (qual == NULL)
return;
if (parsetree->commandType == CMD_UTILITY)
{
/*
* There's noplace to put the qual on a utility statement.
*
* If it's a NOTIFY, silently ignore the qual; this means that the
* NOTIFY will execute, whether or not there are any qualifying
* rows. While clearly wrong, this is much more useful than
* refusing to execute the rule at all, and extra NOTIFY events
* are harmless for typical uses of NOTIFY.
*
* If it isn't a NOTIFY, error out, since unconditional execution of
* other utility stmts is unlikely to be wanted. (This case is
* not currently allowed anyway, but keep the test for safety.)
*/
if (parsetree->utilityStmt && IsA(parsetree->utilityStmt, NotifyStmt))
return;
else
elog(ERROR, "Conditional utility statements are not implemented");
}
/* INTERSECT want's the original, but we need to copy - Jan */
copy = copyObject(qual);
parsetree->jointree->quals = make_and_qual(parsetree->jointree->quals,
copy);
/*
* Make sure query is marked correctly if added qual has sublinks or
* aggregates (not sure it can ever have aggs, but sublinks
* definitely).
*/
parsetree->hasAggs |= checkExprHasAggs(copy);
parsetree->hasSubLinks |= checkExprHasSubLink(copy);
}
/*
* Add the given havingQual to the one already contained in the parsetree
* just as AddQual does for the normal 'where' qual
*/
void
AddHavingQual(Query *parsetree, Node *havingQual)
{
Node *copy;
if (havingQual == NULL)
return;
if (parsetree->commandType == CMD_UTILITY)
{
/*
* There's noplace to put the qual on a utility statement.
*
* See comments in AddQual for motivation.
*/
if (parsetree->utilityStmt && IsA(parsetree->utilityStmt, NotifyStmt))
return;
else
elog(ERROR, "Conditional utility statements are not implemented");
}
/* INTERSECT want's the original, but we need to copy - Jan */
copy = copyObject(havingQual);
parsetree->havingQual = make_and_qual(parsetree->havingQual,
copy);
/*
* Make sure query is marked correctly if added qual has sublinks or
* aggregates (not sure it can ever have aggs, but sublinks
* definitely).
*/
parsetree->hasAggs |= checkExprHasAggs(copy);
parsetree->hasSubLinks |= checkExprHasSubLink(copy);
}
#ifdef NOT_USED
void
AddNotHavingQual(Query *parsetree, Node *havingQual)
{
Node *notqual;
if (havingQual == NULL)
return;
/* Need not copy input qual, because AddHavingQual will... */
notqual = (Node *) make_notclause((Expr *) havingQual);
AddHavingQual(parsetree, notqual);
}
#endif
void
AddNotQual(Query *parsetree, Node *qual)
{
Node *notqual;
if (qual == NULL)
return;
/* Need not copy input qual, because AddQual will... */
notqual = (Node *) make_notclause((Expr *) qual);
AddQual(parsetree, notqual);
}
/* Find a targetlist entry by resno */
static Node *
FindMatchingNew(List *tlist, int attno)
{
List *i;
foreach(i, tlist)
{
TargetEntry *tle = lfirst(i);
if (tle->resdom->resno == attno)
return tle->expr;
}
return NULL;
}
#ifdef NOT_USED
/* Find a targetlist entry by resname */
static Node *
FindMatchingTLEntry(List *tlist, char *e_attname)
{
List *i;
foreach(i, tlist)
{
TargetEntry *tle = lfirst(i);
char *resname;
resname = tle->resdom->resname;
if (strcmp(e_attname, resname) == 0)
return tle->expr;
}
return NULL;
}
#endif
/*
* ResolveNew - replace Vars with corresponding items from a targetlist
*
* Vars matching target_varno and sublevels_up are replaced by the
* entry with matching resno from targetlist, if there is one.
* If not, we either change the unmatched Var's varno to update_varno
* (when event == CMD_UPDATE) or replace it with a constant NULL.
*/
typedef struct
{
int target_varno;
int sublevels_up;
List *targetlist;
int event;
int update_varno;
} ResolveNew_context;
static Node *
ResolveNew_mutator(Node *node, ResolveNew_context *context)
{
if (node == NULL)
return NULL;
if (IsA(node, Var))
{
Var *var = (Var *) node;
int this_varno = (int) var->varno;
int this_varlevelsup = (int) var->varlevelsup;
if (this_varno == context->target_varno &&
this_varlevelsup == context->sublevels_up)
{
Node *n;
/* band-aid: don't do the wrong thing with a whole-tuple Var */
if (var->varattno == InvalidAttrNumber)
elog(ERROR, "ResolveNew: can't handle whole-tuple reference");
n = FindMatchingNew(context->targetlist, var->varattno);
if (n == NULL)
{
if (context->event == CMD_UPDATE)
{
/* For update, just change unmatched var's varno */
var = (Var *) copyObject(node);
var->varno = context->update_varno;
var->varnoold = context->update_varno;
return (Node *) var;
}
else
{
/* Otherwise replace unmatched var with a null */
return (Node *) makeNullConst(var->vartype);
}
}
else
{
/* Make a copy of the tlist item to return */
n = copyObject(n);
/* Adjust varlevelsup if tlist item is from higher query */
if (this_varlevelsup > 0)
IncrementVarSublevelsUp(n, this_varlevelsup, 0);
return n;
}
}
/* 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);
MUTATE(newnode->subselect, sublink->subselect, Node *,
ResolveNew_mutator, context);
return (Node *) newnode;
}
if (IsA(node, Query))
{
Query *query = (Query *) node;
Query *newnode;
FLATCOPY(newnode, query, Query);
context->sublevels_up++;
query_tree_mutator(newnode, ResolveNew_mutator, context, true);
context->sublevels_up--;
return (Node *) newnode;
}
return expression_tree_mutator(node, ResolveNew_mutator,
(void *) context);
}
Node *
ResolveNew(Node *node, int target_varno, int sublevels_up,
List *targetlist, int event, int update_varno)
{
ResolveNew_context context;
context.target_varno = target_varno;
context.sublevels_up = sublevels_up;
context.targetlist = targetlist;
context.event = event;
context.update_varno = update_varno;
/*
* Must be prepared to start with a Query or a bare expression tree;
* if it's a Query, go straight to query_tree_mutator to make sure
* that sublevels_up doesn't get incremented prematurely.
*/
if (node && IsA(node, Query))
{
Query *query = (Query *) node;
Query *newnode;
FLATCOPY(newnode, query, Query);
query_tree_mutator(newnode, ResolveNew_mutator,
(void *) &context, true);
return (Node *) newnode;
}
else
return ResolveNew_mutator(node, &context);
}
#ifdef NOT_USED
/*
* HandleRIRAttributeRule
* Replace Vars matching a given RT index with copies of TL expressions.
*
* Handles 'on retrieve to relation.attribute
* do instead retrieve (attribute = expression) w/qual'
*/
typedef struct
{
List *rtable;
List *targetlist;
int rt_index;
int attr_num;
int *modified;
int *badsql;
int sublevels_up;
} HandleRIRAttributeRule_context;
static Node *
HandleRIRAttributeRule_mutator(Node *node,
HandleRIRAttributeRule_context * context)
{
if (node == NULL)
return NULL;
if (IsA(node, Var))
{
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 (Node *) makeNullConst(var->vartype);
}
else
{
char *name_to_look_for;
name_to_look_for = get_attname(getrelid(this_varno,
context->rtable),
this_varattno);
if (name_to_look_for)
{
Node *n;
*context->modified = TRUE;
n = FindMatchingTLEntry(context->targetlist,
name_to_look_for);
if (n == NULL)
return (Node *) makeNullConst(var->vartype);
/* Make a copy of the tlist item to return */
n = copyObject(n);
/*
* Adjust varlevelsup if tlist item is from higher
* query
*/
if (this_varlevelsup > 0)
IncrementVarSublevelsUp(n, this_varlevelsup, 0);
return n;
}
}
}
/* 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);
MUTATE(newnode->subselect, sublink->subselect, Node *,
HandleRIRAttributeRule_mutator, context);
return (Node *) newnode;
}
if (IsA(node, Query))
{
Query *query = (Query *) node;
Query *newnode;
FLATCOPY(newnode, query, Query);
context->sublevels_up++;
query_tree_mutator(newnode, HandleRIRAttributeRule_mutator,
context, true);
context->sublevels_up--;
return (Node *) newnode;
}
return expression_tree_mutator(node, HandleRIRAttributeRule_mutator,
(void *) context);
}
void
HandleRIRAttributeRule(Query *parsetree,
List *rtable,
List *targetlist,
int rt_index,
int attr_num,
int *modified,
int *badsql)
{
HandleRIRAttributeRule_context context;
context.rtable = rtable;
context.targetlist = targetlist;
context.rt_index = rt_index;
context.attr_num = attr_num;
context.modified = modified;
context.badsql = badsql;
context.sublevels_up = 0;
query_tree_mutator(parsetree, HandleRIRAttributeRule_mutator,
(void *) &context, true);
}
#endif /* NOT_USED */
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