Remove overspecification of precision of CURRENT_TIMESTAMP, LOCALTIMESTAMP,

CURRENT_TIME, and LOCALTIME: now they just produce "timestamptz" not
"timestamptz(6)", etc.  This makes the behavior more consistent with our
choice to not assign a specific default precision to column datatypes.
It should also save a few cycles at runtime due to not having to invoke
the round-to-given-precision functions.
I also took the opportunity to translate CURRENT_TIMESTAMP into "now()"
instead of an invocation of the timestamptz input converter --- this should
save a few cycles too.

diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 2603a652922a9f2208f47536c792ab84adb7987f..4ad61ab409a3c068c68c52c08dfaa50b8197d1f5 100644 (file)
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.496 2005/06/22 21:14:29 tgl Exp $
+ *   $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.497 2005/06/24 14:28:06 tgl Exp $
  *
  * HISTORY
  *   AUTHOR            DATE            MAJOR EVENT
@@ -6002,14 +6002,6 @@ ConstDatetime:
                     * - thomas 2001-09-06
                     */
                    $$->timezone = $2;
-                   /* SQL99 specified a default precision of six
-                    * for schema definitions. But for timestamp
-                    * literals we don't want to throw away precision
-                    * so leave this as unspecified for now.
-                    * Later, we may want a different production
-                    * for schemas. - thomas 2001-12-07
-                    */
-                   $$->typmod = -1;
                }
            | TIME '(' Iconst ')' opt_timezone
                {
@@ -6039,11 +6031,6 @@ ConstDatetime:
                        $$ = SystemTypeName("timetz");
                    else
                        $$ = SystemTypeName("time");
-                   /* SQL99 specified a default precision of zero.
-                    * See comments for timestamp above on why we will
-                    * leave this unspecified for now. - thomas 2001-12-07
-                    */
-                   $$->typmod = -1;
                }
        ;
 
@@ -6715,7 +6702,9 @@ func_expr:    func_name '(' ')'
                     *
                     * This could be simplified if we had a way to generate
                     * an expression tree representing runtime application
-                    * of type-input conversion functions...
+                    * of type-input conversion functions.  (As of PG 7.3
+                    * that is actually possible, but not clear that we want
+                    * to rely on it.)
                     */
                    A_Const *s = makeNode(A_Const);
                    TypeName *d;
@@ -6742,12 +6731,6 @@ func_expr:   func_name '(' ')'
                    s->typename = SystemTypeName("text");
 
                    d = SystemTypeName("timetz");
-                   /* SQL99 mandates a default precision of zero for TIME
-                    * fields in schemas. However, for CURRENT_TIME
-                    * let's preserve the microsecond precision we
-                    * might see from the system clock. - thomas 2001-12-07
-                    */
-                   d->typmod = 6;
 
                    $$ = (Node *)makeTypeCast((Node *)s, d);
                }
@@ -6784,25 +6767,15 @@ func_expr:  func_name '(' ')'
            | CURRENT_TIMESTAMP
                {
                    /*
-                    * Translate as "'now'::text::timestamptz".
-                    * See comments for CURRENT_DATE.
-                    */
-                   A_Const *s = makeNode(A_Const);
-                   TypeName *d;
-
-                   s->val.type = T_String;
-                   s->val.val.str = "now";
-                   s->typename = SystemTypeName("text");
-
-                   d = SystemTypeName("timestamptz");
-                   /* SQL99 mandates a default precision of 6 for timestamp.
-                    * Also, that is about as precise as we will get since
-                    * we are using a microsecond time interface.
-                    * - thomas 2001-12-07
+                    * Translate as "now()", since we have a function that
+                    * does exactly what is needed.
                     */
-                   d->typmod = 6;
-
-                   $$ = (Node *)makeTypeCast((Node *)s, d);
+                   FuncCall *n = makeNode(FuncCall);
+                   n->funcname = SystemFuncName("now");
+                   n->args = NIL;
+                   n->agg_star = FALSE;
+                   n->agg_distinct = FALSE;
+                   $$ = (Node *)n;
                }
            | CURRENT_TIMESTAMP '(' Iconst ')'
                {
@@ -6849,12 +6822,6 @@ func_expr:   func_name '(' ')'
                    s->typename = SystemTypeName("text");
 
                    d = SystemTypeName("time");
-                   /* SQL99 mandates a default precision of zero for TIME
-                    * fields in schemas. However, for LOCALTIME
-                    * let's preserve the microsecond precision we
-                    * might see from the system clock. - thomas 2001-12-07
-                    */
-                   d->typmod = 6;
 
                    $$ = (Node *)makeTypeCast((Node *)s, d);
                }
@@ -6902,12 +6869,6 @@ func_expr:   func_name '(' ')'
                    s->typename = SystemTypeName("text");
 
                    d = SystemTypeName("timestamp");
-                   /* SQL99 mandates a default precision of 6 for timestamp.
-                    * Also, that is about as precise as we will get since
-                    * we are using a microsecond time interface.
-                    * - thomas 2001-12-07
-                    */
-                   d->typmod = 6;
 
                    $$ = (Node *)makeTypeCast((Node *)s, d);
                }