diff options
Diffstat (limited to 'src/backend/optimizer/util/clauses.c')
| -rw-r--r-- | src/backend/optimizer/util/clauses.c | 39 |
1 files changed, 26 insertions, 13 deletions
diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c index 1fc91f0cae8..066b3918264 100644 --- a/src/backend/optimizer/util/clauses.c +++ b/src/backend/optimizer/util/clauses.c @@ -7,7 +7,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.53 1999/10/02 04:37:52 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.54 1999/10/07 04:23:08 tgl Exp $ * * HISTORY * AUTHOR DATE MAJOR EVENT @@ -34,6 +34,11 @@ #include "utils/syscache.h" +/* note that pg_type.h hardwires size of bool as 1 ... duplicate it */ +#define MAKEBOOLCONST(val,isnull) \ + ((Node *) makeConst(BOOLOID, 1, (Datum) (val), \ + (isnull), true, false, false)) + typedef struct { List *groupClause; List *targetList; @@ -312,17 +317,20 @@ make_andclause(List *andclauses) } /* - * Sometimes (such as in the result of cnfify), we use lists of expression - * nodes with implicit AND semantics. These functions convert between an - * AND-semantics expression list and the ordinary representation of a - * boolean expression. + * Sometimes (such as in the result of canonicalize_qual or the input of + * ExecQual), we use lists of expression nodes with implicit AND semantics. + * + * These functions convert between an AND-semantics expression list and the + * ordinary representation of a boolean expression. + * + * Note that an empty list is considered equivalent to TRUE. */ Expr * make_ands_explicit(List *andclauses) { if (andclauses == NIL) - return NULL; - else if (length(andclauses) == 1) + return (Expr *) MAKEBOOLCONST(true, false); + else if (lnext(andclauses) == NIL) return (Expr *) lfirst(andclauses); else return make_andclause(andclauses); @@ -331,10 +339,20 @@ make_ands_explicit(List *andclauses) List * make_ands_implicit(Expr *clause) { + /* + * NB: because the parser sets the qual field to NULL in a query that + * has no WHERE clause, we must consider a NULL input clause as TRUE, + * even though one might more reasonably think it FALSE. Grumble. + * If this causes trouble, consider changing the parser's behavior. + */ if (clause == NULL) - return NIL; + return NIL; /* NULL -> NIL list == TRUE */ else if (and_clause((Node *) clause)) return clause->args; + else if (IsA(clause, Const) && + ! ((Const *) clause)->constisnull && + DatumGetInt32(((Const *) clause)->constvalue)) + return NIL; /* constant TRUE input -> NIL list */ else return lcons(clause, NIL); } @@ -808,11 +826,6 @@ eval_const_expressions(Node *node) return eval_const_expressions_mutator(node, NULL); } -/* note that pg_type.h hardwires size of bool as 1 ... duplicate it */ -#define MAKEBOOLCONST(val,isnull) \ - ((Node *) makeConst(BOOLOID, 1, (Datum) (val), \ - (isnull), true, false, false)) - static Node * eval_const_expressions_mutator (Node *node, void *context) { |