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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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88
src/backend/commands/typecmds.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/typecmds.c,v 1.108 2007/09/29 17:18:58 tgl Exp $
* $PostgreSQL: pgsql/src/backend/commands/typecmds.c,v 1.109 2007/10/29 19:40:39 tgl Exp $
*
* DESCRIPTION
* The "DefineFoo" routines take the parse tree and pick out the
@ -765,20 +765,40 @@ DefineDomain(CreateDomainStmt *stmt)
domainName);
/*
* Expression must be stored as a nodeToString result, but
* we also require a valid textual representation (mainly
* to make life easier for pg_dump).
* If the expression is just a NULL constant, we treat
* it like not having a default.
*
* Note that if the basetype is another domain, we'll see
* a CoerceToDomain expr here and not discard the default.
* This is critical because the domain default needs to be
* retained to override any default that the base domain
* might have.
*/
defaultValue =
deparse_expression(defaultExpr,
deparse_context_for(domainName,
InvalidOid),
false, false);
defaultValueBin = nodeToString(defaultExpr);
if (defaultExpr == NULL ||
(IsA(defaultExpr, Const) &&
((Const *) defaultExpr)->constisnull))
{
defaultValue = NULL;
defaultValueBin = NULL;
}
else
{
/*
* Expression must be stored as a nodeToString result,
* but we also require a valid textual representation
* (mainly to make life easier for pg_dump).
*/
defaultValue =
deparse_expression(defaultExpr,
deparse_context_for(domainName,
InvalidOid),
false, false);
defaultValueBin = nodeToString(defaultExpr);
}
}
else
{
/* DEFAULT NULL is same as not having a default */
/* No default (can this still happen?) */
defaultValue = NULL;
defaultValueBin = NULL;
}
@ -1443,7 +1463,7 @@ AlterDomainDefault(List *names, Node *defaultRaw)
MemSet(new_record_nulls, ' ', sizeof(new_record_nulls));
MemSet(new_record_repl, ' ', sizeof(new_record_repl));
/* Store the new default, if null then skip this step */
/* Store the new default into the tuple */
if (defaultRaw)
{
/* Create a dummy ParseState for transformExpr */
@ -1459,30 +1479,46 @@ AlterDomainDefault(List *names, Node *defaultRaw)
NameStr(typTup->typname));
/*
* Expression must be stored as a nodeToString result, but we also
* require a valid textual representation (mainly to make life easier
* for pg_dump).
* If the expression is just a NULL constant, we treat the command
* like ALTER ... DROP DEFAULT. (But see note for same test in
* DefineDomain.)
*/
defaultValue = deparse_expression(defaultExpr,
if (defaultExpr == NULL ||
(IsA(defaultExpr, Const) && ((Const *) defaultExpr)->constisnull))
{
/* Default is NULL, drop it */
new_record_nulls[Anum_pg_type_typdefaultbin - 1] = 'n';
new_record_repl[Anum_pg_type_typdefaultbin - 1] = 'r';
new_record_nulls[Anum_pg_type_typdefault - 1] = 'n';
new_record_repl[Anum_pg_type_typdefault - 1] = 'r';
}
else
{
/*
* Expression must be stored as a nodeToString result, but we also
* require a valid textual representation (mainly to make life
* easier for pg_dump).
*/
defaultValue = deparse_expression(defaultExpr,
deparse_context_for(NameStr(typTup->typname),
InvalidOid),
false, false);
/*
* Form an updated tuple with the new default and write it back.
*/
new_record[Anum_pg_type_typdefaultbin - 1] = DirectFunctionCall1(textin,
CStringGetDatum(
nodeToString(defaultExpr)));
/*
* Form an updated tuple with the new default and write it back.
*/
new_record[Anum_pg_type_typdefaultbin - 1] = DirectFunctionCall1(textin,
CStringGetDatum(nodeToString(defaultExpr)));
new_record_repl[Anum_pg_type_typdefaultbin - 1] = 'r';
new_record[Anum_pg_type_typdefault - 1] = DirectFunctionCall1(textin,
new_record_repl[Anum_pg_type_typdefaultbin - 1] = 'r';
new_record[Anum_pg_type_typdefault - 1] = DirectFunctionCall1(textin,
CStringGetDatum(defaultValue));
new_record_repl[Anum_pg_type_typdefault - 1] = 'r';
new_record_repl[Anum_pg_type_typdefault - 1] = 'r';
}
}
else
/* Default is NULL, drop it */
{
/* ALTER ... DROP DEFAULT */
new_record_nulls[Anum_pg_type_typdefaultbin - 1] = 'n';
new_record_repl[Anum_pg_type_typdefaultbin - 1] = 'r';
new_record_nulls[Anum_pg_type_typdefault - 1] = 'n';