*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.161 2004/01/10 18:13:53 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.162 2004/01/12 20:48:15 tgl Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
static bool contain_volatile_functions_walker(Node *node, void *context);
static bool contain_nonstrict_functions_walker(Node *node, void *context);
static Node *eval_const_expressions_mutator(Node *node, List *active_fns);
+static List *simplify_or_arguments(List *args,
+ bool *haveNull, bool *forceTrue);
+static List *simplify_and_arguments(List *args,
+ bool *haveNull, bool *forceFalse);
static Expr *simplify_function(Oid funcid, Oid result_type, List *args,
bool allow_inline, List *active_fns);
static Expr *evaluate_function(Oid funcid, Oid result_type, List *args,
* Variant of make_andclause for ANDing two qual conditions together.
* Qual conditions have the property that a NULL nodetree is interpreted
* as 'true'.
+ *
+ * NB: this makes no attempt to preserve AND/OR flatness; so it should not
+ * be used on a qual that has already been run through prepqual.c.
*/
Node *
make_and_qual(Node *qual1, Node *qual2)
{
BoolExpr *expr = (BoolExpr *) node;
List *args;
- Const *const_input;
/*
* Reduce constants in the BoolExpr's arguments. We know args is
{
case OR_EXPR:
{
- /*----------
- * OR arguments are handled as follows:
- * non constant: keep
- * FALSE: drop (does not affect result)
- * TRUE: force result to TRUE
- * NULL: keep only one
- * We keep one NULL input because ExecEvalOr returns NULL
- * when no input is TRUE and at least one is NULL.
- *----------
- */
- FastList newargs;
- List *arg;
+ List *newargs;
bool haveNull = false;
bool forceTrue = false;
- FastListInit(&newargs);
- foreach(arg, args)
- {
- if (!IsA(lfirst(arg), Const))
- {
- FastAppend(&newargs, lfirst(arg));
- continue;
- }
- const_input = (Const *) lfirst(arg);
- if (const_input->constisnull)
- haveNull = true;
- else if (DatumGetBool(const_input->constvalue))
- forceTrue = true;
- /* otherwise, we can drop the constant-false input */
- }
-
- /*
- * We could return TRUE before falling out of the
- * loop, but this coding method will be easier to
- * adapt if we ever add a notion of non-removable
- * functions. We'd need to check all the inputs for
- * non-removability.
- */
+ newargs = simplify_or_arguments(args,
+ &haveNull, &forceTrue);
if (forceTrue)
return MAKEBOOLCONST(true, false);
if (haveNull)
- FastAppend(&newargs, MAKEBOOLCONST(false, true));
+ newargs = lappend(newargs, MAKEBOOLCONST(false, true));
/* If all the inputs are FALSE, result is FALSE */
- if (FastListValue(&newargs) == NIL)
+ if (newargs == NIL)
return MAKEBOOLCONST(false, false);
/* If only one nonconst-or-NULL input, it's the result */
- if (lnext(FastListValue(&newargs)) == NIL)
- return (Node *) lfirst(FastListValue(&newargs));
+ if (lnext(newargs) == NIL)
+ return (Node *) lfirst(newargs);
/* Else we still need an OR node */
- return (Node *) make_orclause(FastListValue(&newargs));
+ return (Node *) make_orclause(newargs);
}
case AND_EXPR:
{
- /*----------
- * AND arguments are handled as follows:
- * non constant: keep
- * TRUE: drop (does not affect result)
- * FALSE: force result to FALSE
- * NULL: keep only one
- * We keep one NULL input because ExecEvalAnd returns NULL
- * when no input is FALSE and at least one is NULL.
- *----------
- */
- FastList newargs;
- List *arg;
+ List *newargs;
bool haveNull = false;
bool forceFalse = false;
- FastListInit(&newargs);
- foreach(arg, args)
- {
- if (!IsA(lfirst(arg), Const))
- {
- FastAppend(&newargs, lfirst(arg));
- continue;
- }
- const_input = (Const *) lfirst(arg);
- if (const_input->constisnull)
- haveNull = true;
- else if (!DatumGetBool(const_input->constvalue))
- forceFalse = true;
- /* otherwise, we can drop the constant-true input */
- }
-
- /*
- * We could return FALSE before falling out of the
- * loop, but this coding method will be easier to
- * adapt if we ever add a notion of non-removable
- * functions. We'd need to check all the inputs for
- * non-removability.
- */
+ newargs = simplify_and_arguments(args,
+ &haveNull, &forceFalse);
if (forceFalse)
return MAKEBOOLCONST(false, false);
if (haveNull)
- FastAppend(&newargs, MAKEBOOLCONST(false, true));
+ newargs = lappend(newargs, MAKEBOOLCONST(false, true));
/* If all the inputs are TRUE, result is TRUE */
- if (FastListValue(&newargs) == NIL)
+ if (newargs == NIL)
return MAKEBOOLCONST(true, false);
/* If only one nonconst-or-NULL input, it's the result */
- if (lnext(FastListValue(&newargs)) == NIL)
- return (Node *) lfirst(FastListValue(&newargs));
+ if (lnext(newargs) == NIL)
+ return (Node *) lfirst(newargs);
/* Else we still need an AND node */
- return (Node *) make_andclause(FastListValue(&newargs));
+ return (Node *) make_andclause(newargs);
}
case NOT_EXPR:
Assert(length(args) == 1);
if (IsA(lfirst(args), Const))
{
- const_input = (Const *) lfirst(args);
+ Const *const_input = (Const *) lfirst(args);
+
/* NOT NULL => NULL */
if (const_input->constisnull)
return MAKEBOOLCONST(false, true);
return MAKEBOOLCONST(!DatumGetBool(const_input->constvalue),
false);
}
+ else if (not_clause((Node *) lfirst(args)))
+ {
+ /* Cancel NOT/NOT */
+ return (Node *) get_notclausearg((Expr *) lfirst(args));
+ }
/* Else we still need a NOT node */
- return (Node *) make_notclause(lfirst(args));
+ return (Node *) make_notclause((Expr *) lfirst(args));
default:
elog(ERROR, "unrecognized boolop: %d",
(int) expr->boolop);
(void *) active_fns);
}
+/*
+ * Subroutine for eval_const_expressions: scan the arguments of an OR clause
+ *
+ * OR arguments are handled as follows:
+ * non constant: keep
+ * FALSE: drop (does not affect result)
+ * TRUE: force result to TRUE
+ * NULL: keep only one
+ * We must keep one NULL input because ExecEvalOr returns NULL when no input
+ * is TRUE and at least one is NULL.
+ *
+ * This is split out as a subroutine so that we can recurse to fold sub-ORs
+ * into the upper OR clause, thereby preserving AND/OR flatness.
+ *
+ * The output arguments *haveNull and *forceTrue must be initialized FALSE
+ * by the caller. They will be set TRUE if a null constant or true constant,
+ * respectively, is detected anywhere in the argument list.
+ */
+static List *
+simplify_or_arguments(List *args, bool *haveNull, bool *forceTrue)
+{
+ List *newargs = NIL;
+ List *larg;
+
+ foreach(larg, args)
+ {
+ Node *arg = (Node *) lfirst(larg);
+
+ if (IsA(arg, Const))
+ {
+ Const *const_input = (Const *) arg;
+
+ if (const_input->constisnull)
+ *haveNull = true;
+ else if (DatumGetBool(const_input->constvalue))
+ {
+ *forceTrue = true;
+ /*
+ * Once we detect a TRUE result we can just exit the loop
+ * immediately. However, if we ever add a notion of
+ * non-removable functions, we'd need to keep scanning.
+ */
+ return NIL;
+ }
+ /* otherwise, we can drop the constant-false input */
+ }
+ else if (or_clause(arg))
+ {
+ newargs = nconc(newargs,
+ simplify_or_arguments(((BoolExpr *) arg)->args,
+ haveNull, forceTrue));
+ }
+ else
+ {
+ newargs = lappend(newargs, arg);
+ }
+ }
+
+ return newargs;
+}
+
+/*
+ * Subroutine for eval_const_expressions: scan the arguments of an AND clause
+ *
+ * AND arguments are handled as follows:
+ * non constant: keep
+ * TRUE: drop (does not affect result)
+ * FALSE: force result to FALSE
+ * NULL: keep only one
+ * We must keep one NULL input because ExecEvalAnd returns NULL when no input
+ * is FALSE and at least one is NULL.
+ *
+ * This is split out as a subroutine so that we can recurse to fold sub-ANDs
+ * into the upper AND clause, thereby preserving AND/OR flatness.
+ *
+ * The output arguments *haveNull and *forceFalse must be initialized FALSE
+ * by the caller. They will be set TRUE if a null constant or false constant,
+ * respectively, is detected anywhere in the argument list.
+ */
+static List *
+simplify_and_arguments(List *args, bool *haveNull, bool *forceFalse)
+{
+ List *newargs = NIL;
+ List *larg;
+
+ foreach(larg, args)
+ {
+ Node *arg = (Node *) lfirst(larg);
+
+ if (IsA(arg, Const))
+ {
+ Const *const_input = (Const *) arg;
+
+ if (const_input->constisnull)
+ *haveNull = true;
+ else if (!DatumGetBool(const_input->constvalue))
+ {
+ *forceFalse = true;
+ /*
+ * Once we detect a FALSE result we can just exit the loop
+ * immediately. However, if we ever add a notion of
+ * non-removable functions, we'd need to keep scanning.
+ */
+ return NIL;
+ }
+ /* otherwise, we can drop the constant-true input */
+ }
+ else if (and_clause(arg))
+ {
+ newargs = nconc(newargs,
+ simplify_and_arguments(((BoolExpr *) arg)->args,
+ haveNull, forceFalse));
+ }
+ else
+ {
+ newargs = lappend(newargs, arg);
+ }
+ }
+
+ return newargs;
+}
+
/*
* Subroutine for eval_const_expressions: try to simplify a function call
* (which might originally have been an operator; we don't care)
projects / users / rhaas / postgres.git / commitdiff