*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepqual.c,v 1.10 1998/09/01 03:23:43 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepqual.c,v 1.11 1998/10/04 03:30:56 momjian Exp $
*
*-------------------------------------------------------------------------
*/
static Expr *normalize(Expr *qual);
static List *or_normalize(List *orlist);
static List *distribute_args(List *item, List *args);
-static List *qualcleanup(Expr *qual);
+static List *qual_cleanup(Expr *qual);
static List *remove_ands(Expr *qual);
static List *remove_duplicates(List *list);
/*
- * cnfify--
+ * cnfify
* Convert a qualification to conjunctive normal form by applying
* successive normalizations.
*
{
newqual = find_nots(pull_args(qual));
newqual = normalize(pull_args(newqual));
- newqual = (Expr *) qualcleanup(pull_args(newqual));
+ newqual = (Expr *) qual_cleanup(pull_args(newqual));
newqual = pull_args(newqual);;
if (removeAndFlag)
newqual = (Expr *) remove_ands(make_andclause(lcons(newqual, NIL)));
}
}
- else if (qual != NULL)
- newqual = (Expr *) lcons(qual, NIL);
return (List *) (newqual);
}
/*
- * pull-args--
- * Given a qualification, eliminate nested 'and' and 'or' clauses.
+ * find_nots
+ * Traverse the qualification, looking for 'not's to take care of.
+ * For 'not' clauses, remove the 'not' and push it down to the clauses'
+ * descendants.
+ * For all other clause types, simply recurse.
*
* Returns the modified qualification.
*
*/
static Expr *
-pull_args(Expr *qual)
+find_nots(Expr *qual)
{
if (qual == NULL)
return NULL;
if (is_opclause((Node *) qual))
{
return (make_clause(qual->opType, qual->oper,
- lcons(pull_args((Expr *) get_leftop(qual)),
- lcons(pull_args((Expr *) get_rightop(qual)),
+ lcons(find_nots((Expr *) get_leftop(qual)),
+ lcons(find_nots((Expr *) get_rightop(qual)),
NIL))));
}
else if (and_clause((Node *) qual))
List *t_list = NIL;
foreach(temp, qual->args)
- t_list = lappend(t_list, pull_args(lfirst(temp)));
- return make_andclause(pull_ands(t_list));
+ t_list = lappend(t_list, find_nots(lfirst(temp)));
+
+ return make_andclause(t_list);
}
else if (or_clause((Node *) qual))
{
List *t_list = NIL;
foreach(temp, qual->args)
- t_list = lappend(t_list, pull_args(lfirst(temp)));
- return make_orclause(pull_ors(t_list));
+ t_list = lappend(t_list, find_nots(lfirst(temp)));
+ return make_orclause(t_list);
}
else if (not_clause((Node *) qual))
- return make_notclause(pull_args(get_notclausearg(qual)));
+ return push_nots(get_notclausearg(qual));
else
return qual;
}
/*
- * pull-ors--
- * Pull the arguments of an 'or' clause nested within another 'or'
- * clause up into the argument list of the parent.
+ * normalize
+ * Given a qualification tree with the 'not's pushed down, convert it
+ * to a tree in CNF by repeatedly applying the rule:
+ * ("OR" A ("AND" B C)) => ("AND" ("OR" A B) ("OR" A C))
+ * bottom-up.
+ * Note that 'or' clauses will always be turned into 'and' clauses.
+ *
+ * Returns the modified qualification.
*
- * Returns the modified list.
*/
-static List *
-pull_ors(List *orlist)
+static Expr *
+normalize(Expr *qual)
{
- if (orlist == NIL)
- return NIL;
+ if (qual == NULL)
+ return NULL;
- if (or_clause(lfirst(orlist)))
+ if (is_opclause((Node *) qual))
{
- List *args = ((Expr *) lfirst(orlist))->args;
+ Expr *expr = (Expr *) qual;
- return (pull_ors(nconc(copyObject((Node *) args),
- copyObject((Node *) lnext(orlist)))));
+ return (make_clause(expr->opType, expr->oper,
+ lcons(normalize((Expr *) get_leftop(qual)),
+ lcons(normalize((Expr *) get_rightop(qual)),
+ NIL))));
}
+ else if (and_clause((Node *) qual))
+ {
+ List *temp = NIL;
+ List *t_list = NIL;
+
+ foreach(temp, qual->args)
+ t_list = lappend(t_list, normalize(lfirst(temp)));
+ return make_andclause(t_list);
+ }
+ else if (or_clause((Node *) qual))
+ {
+ /* XXX - let form, maybe incorrect */
+ List *orlist = NIL;
+ List *temp = NIL;
+ bool has_andclause = FALSE;
+
+ foreach(temp, qual->args)
+ orlist = lappend(orlist, normalize(lfirst(temp)));
+ foreach(temp, orlist)
+ {
+ if (and_clause(lfirst(temp)))
+ {
+ has_andclause = TRUE;
+ break;
+ }
+ }
+ if (has_andclause == TRUE)
+ return make_andclause(or_normalize(orlist));
+ else
+ return make_orclause(orlist);
+
+ }
+ else if (not_clause((Node *) qual))
+ return make_notclause(normalize(get_notclausearg(qual)));
else
- return lcons(lfirst(orlist), pull_ors(lnext(orlist)));
+ return qual;
}
/*
- * pull-ands--
- * Pull the arguments of an 'and' clause nested within another 'and'
- * clause up into the argument list of the parent.
+ * qual_cleanup
+ * Fix up a qualification by removing duplicate entries (left over from
+ * normalization), and by removing 'and' and 'or' clauses which have only
+ * one valid expr (e.g., ("AND" A) => A).
+ *
+ * Returns the modified qualfication.
*
- * Returns the modified list.
*/
static List *
-pull_ands(List *andlist)
+qual_cleanup(Expr *qual)
{
- if (andlist == NIL)
+ if (qual == NULL)
return NIL;
- if (and_clause(lfirst(andlist)))
+ if (is_opclause((Node *) qual))
{
- List *args = ((Expr *) lfirst(andlist))->args;
+ return ((List *) make_clause(qual->opType, qual->oper,
+ lcons(qual_cleanup((Expr *) get_leftop(qual)),
+ lcons(qual_cleanup((Expr *) get_rightop(qual)),
+ NIL))));
+ }
+ else if (and_clause((Node *) qual))
+ {
+ List *temp = NIL;
+ List *t_list = NIL;
+ List *new_and_args = NIL;
- return (pull_ands(nconc(copyObject((Node *) args),
- copyObject((Node *) lnext(andlist)))));
+ foreach(temp, qual->args)
+ t_list = lappend(t_list, qual_cleanup(lfirst(temp)));
+
+ new_and_args = remove_duplicates(t_list);
+
+ if (length(new_and_args) > 1)
+ return (List *) make_andclause(new_and_args);
+ else
+ return lfirst(new_and_args);
}
+ else if (or_clause((Node *) qual))
+ {
+ List *temp = NIL;
+ List *t_list = NIL;
+ List *new_or_args = NIL;
+
+ foreach(temp, qual->args)
+ t_list = lappend(t_list, qual_cleanup(lfirst(temp)));
+
+ new_or_args = remove_duplicates(t_list);
+
+
+ if (length(new_or_args) > 1)
+ return (List *) make_orclause(new_or_args);
+ else
+ return lfirst(new_or_args);
+ }
+ else if (not_clause((Node *) qual))
+ return (List *) make_notclause((Expr *) qual_cleanup((Expr *) get_notclausearg(qual)));
else
- return lcons(lfirst(andlist), pull_ands(lnext(andlist)));
+ return (List *) qual;
}
/*
- * find-nots--
- * Traverse the qualification, looking for 'not's to take care of.
- * For 'not' clauses, remove the 'not' and push it down to the clauses'
- * descendants.
- * For all other clause types, simply recurse.
+ * pull_args
+ * Given a qualification, eliminate nested 'and' and 'or' clauses.
*
* Returns the modified qualification.
*
*/
static Expr *
-find_nots(Expr *qual)
+pull_args(Expr *qual)
{
if (qual == NULL)
return NULL;
if (is_opclause((Node *) qual))
{
return (make_clause(qual->opType, qual->oper,
- lcons(find_nots((Expr *) get_leftop(qual)),
- lcons(find_nots((Expr *) get_rightop(qual)),
+ lcons(pull_args((Expr *) get_leftop(qual)),
+ lcons(pull_args((Expr *) get_rightop(qual)),
NIL))));
}
else if (and_clause((Node *) qual))
List *t_list = NIL;
foreach(temp, qual->args)
- t_list = lappend(t_list, find_nots(lfirst(temp)));
-
- return make_andclause(t_list);
+ t_list = lappend(t_list, pull_args(lfirst(temp)));
+ return make_andclause(pull_ands(t_list));
}
else if (or_clause((Node *) qual))
{
List *t_list = NIL;
foreach(temp, qual->args)
- t_list = lappend(t_list, find_nots(lfirst(temp)));
- return make_orclause(t_list);
+ t_list = lappend(t_list, pull_args(lfirst(temp)));
+ return make_orclause(pull_ors(t_list));
}
else if (not_clause((Node *) qual))
- return push_nots(get_notclausearg(qual));
+ return make_notclause(pull_args(get_notclausearg(qual)));
else
return qual;
}
/*
- * push-nots--
+ * pull_ors
+ * Pull the arguments of an 'or' clause nested within another 'or'
+ * clause up into the argument list of the parent.
+ *
+ * Returns the modified list.
+ */
+static List *
+pull_ors(List *orlist)
+{
+ if (orlist == NIL)
+ return NIL;
+
+ if (or_clause(lfirst(orlist)))
+ {
+ List *args = ((Expr *) lfirst(orlist))->args;
+
+ return (pull_ors(nconc(copyObject((Node *) args),
+ copyObject((Node *) lnext(orlist)))));
+ }
+ else
+ return lcons(lfirst(orlist), pull_ors(lnext(orlist)));
+}
+
+/*
+ * pull_ands
+ * Pull the arguments of an 'and' clause nested within another 'and'
+ * clause up into the argument list of the parent.
+ *
+ * Returns the modified list.
+ */
+static List *
+pull_ands(List *andlist)
+{
+ if (andlist == NIL)
+ return NIL;
+
+ if (and_clause(lfirst(andlist)))
+ {
+ List *args = ((Expr *) lfirst(andlist))->args;
+
+ return (pull_ands(nconc(copyObject((Node *) args),
+ copyObject((Node *) lnext(andlist)))));
+ }
+ else
+ return lcons(lfirst(andlist), pull_ands(lnext(andlist)));
+}
+
+/*
+ * push_nots
* Negate the descendants of a 'not' clause.
*
* Returns the modified qualification.
}
/*
- * normalize--
- * Given a qualification tree with the 'not's pushed down, convert it
- * to a tree in CNF by repeatedly applying the rule:
- * ("OR" A ("AND" B C)) => ("AND" ("OR" A B) ("OR" A C))
- * bottom-up.
- * Note that 'or' clauses will always be turned into 'and' clauses.
- *
- * Returns the modified qualification.
- *
- */
-static Expr *
-normalize(Expr *qual)
-{
- if (qual == NULL)
- return NULL;
-
- if (is_opclause((Node *) qual))
- {
- Expr *expr = (Expr *) qual;
-
- return (make_clause(expr->opType, expr->oper,
- lcons(normalize((Expr *) get_leftop(qual)),
- lcons(normalize((Expr *) get_rightop(qual)),
- NIL))));
- }
- else if (and_clause((Node *) qual))
- {
- List *temp = NIL;
- List *t_list = NIL;
-
- foreach(temp, qual->args)
- t_list = lappend(t_list, normalize(lfirst(temp)));
- return make_andclause(t_list);
- }
- else if (or_clause((Node *) qual))
- {
- /* XXX - let form, maybe incorrect */
- List *orlist = NIL;
- List *temp = NIL;
- bool has_andclause = FALSE;
-
- foreach(temp, qual->args)
- orlist = lappend(orlist, normalize(lfirst(temp)));
- foreach(temp, orlist)
- {
- if (and_clause(lfirst(temp)))
- {
- has_andclause = TRUE;
- break;
- }
- }
- if (has_andclause == TRUE)
- return make_andclause(or_normalize(orlist));
- else
- return make_orclause(orlist);
-
- }
- else if (not_clause((Node *) qual))
- return make_notclause(normalize(get_notclausearg(qual)));
- else
- return qual;
-}
-
-/*
- * or-normalize--
+ * or_normalize
* Given a list of exprs which are 'or'ed together, distribute any
* 'and' clauses.
*
}
/*
- * distribute-args--
+ * distribute_args
* Create new 'or' clauses by or'ing 'item' with each element of 'args'.
* E.g.: (distribute-args A ("AND" B C)) => ("AND" ("OR" A B) ("OR" A C))
*
}
/*
- * qualcleanup--
- * Fix up a qualification by removing duplicate entries (left over from
- * normalization), and by removing 'and' and 'or' clauses which have only
- * one valid expr (e.g., ("AND" A) => A).
- *
- * Returns the modified qualfication.
- *
- */
-static List *
-qualcleanup(Expr *qual)
-{
- if (qual == NULL)
- return NIL;
-
- if (is_opclause((Node *) qual))
- {
- return ((List *) make_clause(qual->opType, qual->oper,
- lcons(qualcleanup((Expr *) get_leftop(qual)),
- lcons(qualcleanup((Expr *) get_rightop(qual)),
- NIL))));
- }
- else if (and_clause((Node *) qual))
- {
- List *temp = NIL;
- List *t_list = NIL;
- List *new_and_args = NIL;
-
- foreach(temp, qual->args)
- t_list = lappend(t_list, qualcleanup(lfirst(temp)));
-
- new_and_args = remove_duplicates(t_list);
-
- if (length(new_and_args) > 1)
- return (List *) make_andclause(new_and_args);
- else
- return lfirst(new_and_args);
- }
- else if (or_clause((Node *) qual))
- {
- List *temp = NIL;
- List *t_list = NIL;
- List *new_or_args = NIL;
-
- foreach(temp, qual->args)
- t_list = lappend(t_list, qualcleanup(lfirst(temp)));
-
- new_or_args = remove_duplicates(t_list);
-
-
- if (length(new_or_args) > 1)
- return (List *) make_orclause(new_or_args);
- else
- return lfirst(new_or_args);
- }
- else if (not_clause((Node *) qual))
- return (List *) make_notclause((Expr *) qualcleanup((Expr *) get_notclausearg(qual)));
-
- else
- return (List *) qual;
-}
-
-/*
- * remove-ands--
+ * remove_ands
* Remove the explicit "AND"s from the qualification:
* ("AND" A B) => (A B)
*
return (List *) qual;
}
-/*****************************************************************************
- *
- *
- *
- *****************************************************************************/
-
+/*
+ * remove_duplicates
+ */
static List *
remove_duplicates(List *list)
{
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