database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-11-22 12:22:45 +03:00
Code Activity

Remove the hack in the grammar that "optimized away" DEFAULT NULL clauses.

Browse Source 
Instead put in a test to drop a NULL default at the last moment before
storing the catalog entry.  This changes the behavior in a couple of ways:
* Specifying DEFAULT NULL when creating an inheritance child table will
  successfully suppress inheritance of any default expression from the
  parent's column, where formerly it failed to do so.
* Specifying DEFAULT NULL for a column of a domain type will correctly
  override any default belonging to the domain; likewise for a sub-domain.
The latter change happens because by the time the clause is checked,
it won't be a simple null Const but a CoerceToDomain expression.

Personally I think this should be back-patched, but there doesn't seem to
be consensus for that on pgsql-hackers, so refraining.
This commit is contained in:
Tom Lane
2007-10-29 19:40:40 +00:00
parent bf5ccf382c
commit b17b7fae8c
8 changed files with 115 additions and 69 deletions
Download Patch File Download Diff File Expand all files Collapse all files

38
src/backend/parser/gram.y
View File

@@ -11,7 +11,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.603 2007/09/24 01:29:28 adunstan Exp $
* $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.604 2007/10/29 19:40:39 tgl Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
@@ -1685,14 +1685,7 @@ alter_rel_cmd:
;
alter_column_default:
SET DEFAULT a_expr
{
/* Treat SET DEFAULT NULL the same as DROP DEFAULT */
if (exprIsNullConstant($3))
$$ = NULL;
else
$$ = $3;
}
SET DEFAULT a_expr { $$ = $3; }
| DROP DEFAULT { $$ = NULL; }
;
@@ -2080,15 +2073,7 @@ ColConstraintElem:
Constraint *n = makeNode(Constraint);
n->contype = CONSTR_DEFAULT;
n->name = NULL;
if (exprIsNullConstant($2))
{
/* DEFAULT NULL should be reported as empty expr */
n->raw_expr = NULL;
}
else
{
n->raw_expr = $2;
}
n->raw_expr = $2;
n->cooked_expr = NULL;
n->keys = NULL;
n->indexspace = NULL;
@@ -9763,23 +9748,6 @@ parser_init(void)
QueryIsRule = FALSE;
}
/* exprIsNullConstant()
* Test whether an a_expr is a plain NULL constant or not.
*/
bool
exprIsNullConstant(Node *arg)
{
if (arg && IsA(arg, A_Const))
{
A_Const *con = (A_Const *) arg;
if (con->val.type == T_Null &&
con->typename == NULL)
return TRUE;
}
return FALSE;
}
/* doNegate()
* Handle negation of a numeric constant.
*

17
src/backend/parser/parse_expr.c
View File

@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/parser/parse_expr.c,v 1.221 2007/06/23 22:12:51 tgl Exp $
* $PostgreSQL: pgsql/src/backend/parser/parse_expr.c,v 1.222 2007/10/29 19:40:40 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -606,6 +606,21 @@ transformParamRef(ParseState *pstate, ParamRef *pref)
return (Node *) param;
}
/* Test whether an a_expr is a plain NULL constant or not */
static bool
exprIsNullConstant(Node *arg)
{
if (arg && IsA(arg, A_Const))
{
A_Const *con = (A_Const *) arg;
if (con->val.type == T_Null &&
con->typename == NULL)
return true;
}
return false;
}
static Node *
transformAExprOp(ParseState *pstate, A_Expr *a)
{

3
src/backend/parser/parse_utilcmd.c
View File

@@ -19,7 +19,7 @@
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/backend/parser/parse_utilcmd.c,v 2.3 2007/08/27 03:36:08 tgl Exp $
* $PostgreSQL: pgsql/src/backend/parser/parse_utilcmd.c,v 2.4 2007/10/29 19:40:40 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -440,7 +440,6 @@ transformColumnDefinition(ParseState *pstate, CreateStmtContext *cxt,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("multiple default values specified for column \"%s\" of table \"%s\"",
column->colname, cxt->relation->relname)));
/* Note: DEFAULT NULL maps to constraint->raw_expr == NULL */
column->raw_default = constraint->raw_expr;
Assert(constraint->cooked_expr == NULL);
saw_default = true;