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

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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
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17
src/backend/parser/parse_expr.c
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@ -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)
{