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Tweak querytree-dependency-extraction code so that columns of tables 

that are explicitly JOINed are not considered dependencies unless they
are actually used in the query: mere presence in the joinaliasvars
list of a JOIN RTE doesn't count as being used.  The patch touches
a number of files because I needed to generalize the API of
query_tree_walker to support an additional flag bit, but the changes
are otherwise quite small.
This commit is contained in:
Tom Lane 2002-09-11 14:48:55 +00:00
parent d634a5903f
commit 6fdc44be71
8 changed files with 89 additions and 55 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
src/backend/catalog/dependency.c
View File

@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/catalog/dependency.c,v 1.9 2002/09/04 20:31:13 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/catalog/dependency.c,v 1.10 2002/09/11 14:48:54 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -684,6 +684,12 @@ recordDependencyOnExpr(const ObjectAddress *depender,
/*
* Recursively search an expression tree for object references.
*
* Note: we avoid creating references to columns of tables that participate
* in an SQL JOIN construct, but are not actually used anywhere in the query.
* To do so, we do not scan the joinaliasvars list of a join RTE while
* scanning the query rangetable, but instead scan each individual entry
* of the alias list when we find a reference to it.
*/
static bool
find_expr_references_walker(Node *node,
@ -716,10 +722,24 @@ find_expr_references_walker(Node *node,
elog(ERROR, "find_expr_references_walker: bogus varno %d",
var->varno);
rte = rt_fetch(var->varno, rtable);
/* If it's a plain relation, reference this column */
if (rte->rtekind == RTE_RELATION)
{
/* If it's a plain relation, reference this column */
/* NB: this code works for whole-row Var with attno 0, too */
add_object_address(OCLASS_CLASS, rte->relid, var->varattno,
&context->addrs);
}
else if (rte->rtekind == RTE_JOIN)
{
/* Scan join output column to add references to join inputs */
if (var->varattno <= 0 ||
var->varattno > length(rte->joinaliasvars))
elog(ERROR, "find_expr_references_walker: bogus varattno %d",
var->varattno);
find_expr_references_walker((Node *) nth(var->varattno - 1,
rte->joinaliasvars),
context);
}
return false;
}
if (IsA(node, Expr))
@ -766,7 +786,7 @@ find_expr_references_walker(Node *node,
* Add whole-relation refs for each plain relation mentioned in
* the subquery's rtable. (Note: query_tree_walker takes care of
* recursing into RTE_FUNCTION and RTE_SUBQUERY RTEs, so no need
* to do that here.)
* to do that here. But keep it from looking at join alias lists.)
*/
foreach(rtable, query->rtable)
{
@ -781,7 +801,8 @@ find_expr_references_walker(Node *node,
context->rtables = lcons(query->rtable, context->rtables);
result = query_tree_walker(query,
find_expr_references_walker,
(void *) context, true);
(void *) context,
QTW_IGNORE_JOINALIASES);
context->rtables = lnext(context->rtables);
return result;
}

4
src/backend/optimizer/prep/prepunion.c
View File

@ -14,7 +14,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepunion.c,v 1.78 2002/09/04 20:31:22 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepunion.c,v 1.79 2002/09/11 14:48:55 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -774,7 +774,7 @@ adjust_inherited_attrs(Node *node,
if (newnode->resultRelation == old_rt_index)
newnode->resultRelation = new_rt_index;
query_tree_mutator(newnode, adjust_inherited_attrs_mutator,
(void *) &context, false);
(void *) &context, QTW_IGNORE_SUBQUERIES);
return (Node *) newnode;
}
else

44
src/backend/optimizer/util/clauses.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.108 2002/09/04 20:31:22 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.109 2002/09/11 14:48:54 tgl Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
@ -1788,7 +1788,7 @@ simplify_op_or_func(Expr *expr, List *args)
* {
* adjust context for subquery;
* result = query_tree_walker((Query *) node, my_walker, context,
* true); // to visit subquery RTEs too
* 0); // to visit rtable items too
* restore context if needed;
* return result;
* }
@ -1994,16 +1994,17 @@ expression_tree_walker(Node *node,
* walker intends to descend into subqueries. It is also useful for
* descending into subqueries within a walker.
*
* If visitQueryRTEs is true, the walker will also be called on sub-Query
* nodes present in subquery rangetable entries of the given Query. This
* is optional since some callers handle those sub-queries separately,
* or don't really want to see subqueries anyway.
* Some callers want to suppress visitation of certain items in the sub-Query,
* typically because they need to process them specially, or don't actually
* want to recurse into subqueries. This is supported by the flags argument,
* which is the bitwise OR of flag values to suppress visitation of
* indicated items. (More flag bits may be added as needed.)
*/
bool
query_tree_walker(Query *query,
bool (*walker) (),
void *context,
bool visitQueryRTEs)
int flags)
{
List *rt;
@ -2028,13 +2029,14 @@ query_tree_walker(Query *query,
/* nothing to do */
break;
case RTE_SUBQUERY:
if (visitQueryRTEs)
if (! (flags & QTW_IGNORE_SUBQUERIES))
if (walker(rte->subquery, context))
return true;
break;
case RTE_JOIN:
if (walker(rte->joinaliasvars, context))
return true;
if (! (flags & QTW_IGNORE_JOINALIASES))
if (walker(rte->joinaliasvars, context))
return true;
break;
case RTE_FUNCTION:
if (walker(rte->funcexpr, context))
@ -2388,16 +2390,17 @@ expression_tree_mutator(Node *node,
* if you don't want to change the original. All substructure is safely
* copied, however.
*
* If visitQueryRTEs is true, the mutator will also be called on sub-Query
* nodes present in subquery rangetable entries of the given Query. This
* is optional since some callers handle those sub-queries separately,
* or don't really want to see subqueries anyway.
* Some callers want to suppress mutating of certain items in the sub-Query,
* typically because they need to process them specially, or don't actually
* want to recurse into subqueries. This is supported by the flags argument,
* which is the bitwise OR of flag values to suppress mutating of
* indicated items. (More flag bits may be added as needed.)
*/
void
query_tree_mutator(Query *query,
Node *(*mutator) (),
void *context,
bool visitQueryRTEs)
int flags)
{
List *newrt = NIL;
List *rt;
@ -2420,7 +2423,7 @@ query_tree_mutator(Query *query,
/* nothing to do, don't bother to make a copy */
break;
case RTE_SUBQUERY:
if (visitQueryRTEs)
if (! (flags & QTW_IGNORE_SUBQUERIES))
{
FLATCOPY(newrte, rte, RangeTblEntry);
CHECKFLATCOPY(newrte->subquery, rte->subquery, Query);
@ -2429,9 +2432,12 @@ query_tree_mutator(Query *query,
}
break;
case RTE_JOIN:
FLATCOPY(newrte, rte, RangeTblEntry);
MUTATE(newrte->joinaliasvars, rte->joinaliasvars, List *);
rte = newrte;
if (! (flags & QTW_IGNORE_JOINALIASES))
{
FLATCOPY(newrte, rte, RangeTblEntry);
MUTATE(newrte->joinaliasvars, rte->joinaliasvars, List *);
rte = newrte;
}
break;
case RTE_FUNCTION:
FLATCOPY(newrte, rte, RangeTblEntry);

10
src/backend/optimizer/util/var.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/var.c,v 1.39 2002/09/04 20:31:22 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/var.c,v 1.40 2002/09/11 14:48:54 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -82,7 +82,7 @@ pull_varnos(Node *node)
*/
if (node && IsA(node, Query))
query_tree_walker((Query *) node, pull_varnos_walker,
(void *) &context, true);
(void *) &context, 0);
else
pull_varnos_walker(node, &context);
@ -128,7 +128,7 @@ pull_varnos_walker(Node *node, pull_varnos_context *context)
context->sublevels_up++;
result = query_tree_walker((Query *) node, pull_varnos_walker,
(void *) context, true);
(void *) context, 0);
context->sublevels_up--;
return result;
}
@ -165,7 +165,7 @@ contain_var_reference(Node *node, int varno, int varattno, int levelsup)
if (node && IsA(node, Query))
return query_tree_walker((Query *) node,
contain_var_reference_walker,
(void *) &context, true);
(void *) &context, 0);
else
return contain_var_reference_walker(node, &context);
}
@ -212,7 +212,7 @@ contain_var_reference_walker(Node *node,
context->sublevels_up++;
result = query_tree_walker((Query *) node,
contain_var_reference_walker,
(void *) context, true);
(void *) context, 0);
context->sublevels_up--;
return result;
}

5
src/backend/rewrite/rewriteDefine.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteDefine.c,v 1.79 2002/09/04 20:31:25 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteDefine.c,v 1.80 2002/09/11 14:48:54 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -464,9 +464,10 @@ setRuleCheckAsUser(Query *qry, Oid userid)
}
/* If there are sublinks, search for them and process their RTEs */
/* ignore subqueries in rtable because we already processed them */
if (qry->hasSubLinks)
query_tree_walker(qry, setRuleCheckAsUser_walker, (void *) &userid,
false /* already did the ones in rtable */ );
QTW_IGNORE_SUBQUERIES);
}
/*

7
src/backend/rewrite/rewriteHandler.c
View File

@ -7,7 +7,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteHandler.c,v 1.108 2002/09/04 20:31:25 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteHandler.c,v 1.109 2002/09/11 14:48:54 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -822,11 +822,12 @@ fireRIRrules(Query *parsetree)
}
/*
* Recurse into sublink subqueries, too.
* Recurse into sublink subqueries, too. But we already did the ones
* in the rtable.
*/
if (parsetree->hasSubLinks)
query_tree_walker(parsetree, fireRIRonSubLink, NULL,
false /* already handled the ones in rtable */ );
QTW_IGNORE_SUBQUERIES);
/*
* If the query was marked having aggregates, check if this is still

34
src/backend/rewrite/rewriteManip.c
View File

@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteManip.c,v 1.65 2002/09/04 20:31:25 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteManip.c,v 1.66 2002/09/11 14:48:54 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -49,7 +49,7 @@ checkExprHasAggs(Node *node)
*/
if (node && IsA(node, Query))
return query_tree_walker((Query *) node, checkExprHasAggs_walker,
NULL, false);
NULL, QTW_IGNORE_SUBQUERIES);
else
return checkExprHasAggs_walker(node, NULL);
}
@ -79,7 +79,7 @@ checkExprHasSubLink(Node *node)
*/
if (node && IsA(node, Query))
return query_tree_walker((Query *) node, checkExprHasSubLink_walker,
NULL, false);
NULL, QTW_IGNORE_SUBQUERIES);
else
return checkExprHasSubLink_walker(node, NULL);
}
@ -155,7 +155,7 @@ OffsetVarNodes_walker(Node *node, OffsetVarNodes_context *context)
context->sublevels_up++;
result = query_tree_walker((Query *) node, OffsetVarNodes_walker,
(void *) context, true);
(void *) context, 0);
context->sublevels_up--;
return result;
}
@ -196,7 +196,7 @@ OffsetVarNodes(Node *node, int offset, int sublevels_up)
lfirsti(l) += offset;
}
query_tree_walker(qry, OffsetVarNodes_walker,
(void *) &context, true);
(void *) &context, 0);
}
else
OffsetVarNodes_walker(node, &context);
@ -265,7 +265,7 @@ ChangeVarNodes_walker(Node *node, ChangeVarNodes_context *context)
context->sublevels_up++;
result = query_tree_walker((Query *) node, ChangeVarNodes_walker,
(void *) context, true);
(void *) context, 0);
context->sublevels_up--;
return result;
}
@ -310,7 +310,7 @@ ChangeVarNodes(Node *node, int rt_index, int new_index, int sublevels_up)
}
}
query_tree_walker(qry, ChangeVarNodes_walker,
(void *) &context, true);
(void *) &context, 0);
}
else
ChangeVarNodes_walker(node, &context);
@ -361,7 +361,7 @@ IncrementVarSublevelsUp_walker(Node *node,
context->min_sublevels_up++;
result = query_tree_walker((Query *) node,
IncrementVarSublevelsUp_walker,
(void *) context, true);
(void *) context, 0);
context->min_sublevels_up--;
return result;
}
@ -385,7 +385,7 @@ IncrementVarSublevelsUp(Node *node, int delta_sublevels_up,
*/
if (node && IsA(node, Query))
query_tree_walker((Query *) node, IncrementVarSublevelsUp_walker,
(void *) &context, true);
(void *) &context, 0);
else
IncrementVarSublevelsUp_walker(node, &context);
}
@ -443,7 +443,7 @@ rangeTableEntry_used_walker(Node *node,
context->sublevels_up++;
result = query_tree_walker((Query *) node, rangeTableEntry_used_walker,
(void *) context, true);
(void *) context, 0);
context->sublevels_up--;
return result;
}
@ -466,7 +466,7 @@ rangeTableEntry_used(Node *node, int rt_index, int sublevels_up)
*/
if (node && IsA(node, Query))
return query_tree_walker((Query *) node, rangeTableEntry_used_walker,
(void *) &context, true);
(void *) &context, 0);
else
return rangeTableEntry_used_walker(node, &context);
}
@ -508,7 +508,7 @@ attribute_used_walker(Node *node,
context->sublevels_up++;
result = query_tree_walker((Query *) node, attribute_used_walker,
(void *) context, true);
(void *) context, 0);
context->sublevels_up--;
return result;
}
@ -532,7 +532,7 @@ attribute_used(Node *node, int rt_index, int attno, int sublevels_up)
*/
if (node && IsA(node, Query))
return query_tree_walker((Query *) node, attribute_used_walker,
(void *) &context, true);
(void *) &context, 0);
else
return attribute_used_walker(node, &context);
}
@ -851,7 +851,7 @@ ResolveNew_mutator(Node *node, ResolveNew_context *context)
FLATCOPY(newnode, query, Query);
context->sublevels_up++;
query_tree_mutator(newnode, ResolveNew_mutator, context, true);
query_tree_mutator(newnode, ResolveNew_mutator, context, 0);
context->sublevels_up--;
return (Node *) newnode;
}
@ -883,7 +883,7 @@ ResolveNew(Node *node, int target_varno, int sublevels_up,
FLATCOPY(newnode, query, Query);
query_tree_mutator(newnode, ResolveNew_mutator,
(void *) &context, true);
(void *) &context, 0);
return (Node *) newnode;
}
else
@ -991,7 +991,7 @@ HandleRIRAttributeRule_mutator(Node *node,
FLATCOPY(newnode, query, Query);
context->sublevels_up++;
query_tree_mutator(newnode, HandleRIRAttributeRule_mutator,
context, true);
context, 0);
context->sublevels_up--;
return (Node *) newnode;
}
@ -1019,7 +1019,7 @@ HandleRIRAttributeRule(Query *parsetree,
context.sublevels_up = 0;
query_tree_mutator(parsetree, HandleRIRAttributeRule_mutator,
(void *) &context, true);
(void *) &context, 0);
}
#endif /* NOT_USED */

11
src/include/optimizer/clauses.h
View File

@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: clauses.h,v 1.53 2002/06/20 20:29:51 momjian Exp $
* $Id: clauses.h,v 1.54 2002/09/11 14:48:55 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -66,10 +66,15 @@ extern bool expression_tree_walker(Node *node, bool (*walker) (),
void *context);
extern Node *expression_tree_mutator(Node *node, Node *(*mutator) (),
void *context);
/* flags bits for query_tree_walker and query_tree_mutator */
#define QTW_IGNORE_SUBQUERIES 0x01 /* subqueries in rtable */
#define QTW_IGNORE_JOINALIASES 0x02 /* JOIN alias var lists */
extern bool query_tree_walker(Query *query, bool (*walker) (),
void *context, bool visitQueryRTEs);
void *context, int flags);
extern void query_tree_mutator(Query *query, Node *(*mutator) (),
void *context, bool visitQueryRTEs);
void *context, int flags);
#define is_subplan(clause) ((clause) != NULL && \
IsA(clause, Expr) && \