From b17b7fae8c1418f924915348afaa2250d1360bc4 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Mon, 29 Oct 2007 19:40:40 +0000
Subject: [PATCH] Remove the hack in the grammar that "optimized away" DEFAULT
NULL clauses. 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.
---
src/backend/catalog/heap.c | 17 +++++-
src/backend/commands/typecmds.c | 88 ++++++++++++++++++++--------
src/backend/parser/gram.y | 38 +-----------
src/backend/parser/parse_expr.c | 17 +++++-
src/backend/parser/parse_utilcmd.c | 3 +-
src/include/parser/gramparse.h | 3 +-
src/test/regress/expected/domain.out | 10 +++-
src/test/regress/sql/domain.sql | 8 ++-
8 files changed, 115 insertions(+), 69 deletions(-)
diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
index ea985a635dd..d22bb77a50c 100644
--- a/src/backend/catalog/heap.c
+++ b/src/backend/catalog/heap.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/catalog/heap.c,v 1.324 2007/10/12 18:55:11 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/catalog/heap.c,v 1.325 2007/10/29 19:40:39 tgl Exp $
*
*
* INTERFACE ROUTINES
@@ -1722,6 +1722,21 @@ AddRelationRawConstraints(Relation rel,
atp->atttypid, atp->atttypmod,
NameStr(atp->attname));
+ /*
+ * If the expression is just a NULL constant, we do not bother
+ * to make an explicit pg_attrdef entry, since the default behavior
+ * is equivalent.
+ *
+ * Note a nonobvious property of this test: if the column is of a
+ * domain type, what we'll get is not a bare null Const but a
+ * CoerceToDomain expr, so we will not discard the default. This is
+ * critical because the column default needs to be retained to
+ * override any default that the domain might have.
+ */
+ if (expr == NULL ||
+ (IsA(expr, Const) && ((Const *) expr)->constisnull))
+ continue;
+
StoreAttrDefault(rel, colDef->attnum, nodeToString(expr));
cooked = (CookedConstraint *) palloc(sizeof(CookedConstraint));
diff --git a/src/backend/commands/typecmds.c b/src/backend/commands/typecmds.c
index 75a8b7530e8..1f58d989f26 100644
--- a/src/backend/commands/typecmds.c
+++ b/src/backend/commands/typecmds.c
@@ -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';
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 1452fe7ff2b..f9f7a49a312 100644
--- 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 2.603 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.
*
diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index 754e18d687c..86fddc4a7a6 100644
--- a/src/backend/parser/parse_expr.c
+++ b/src/backend/parser/parse_expr.c
@@ -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)
{
diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c
index 54e7dfdb161..287e82ddeec 100644
--- a/src/backend/parser/parse_utilcmd.c
+++ b/src/backend/parser/parse_utilcmd.c
@@ -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;
diff --git a/src/include/parser/gramparse.h b/src/include/parser/gramparse.h
index ee6be87c02f..34f47a9bea6 100644
--- a/src/include/parser/gramparse.h
+++ b/src/include/parser/gramparse.h
@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/parser/gramparse.h,v 1.38 2007/01/05 22:19:56 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/parser/gramparse.h,v 1.39 2007/10/29 19:40:40 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -54,6 +54,5 @@ extern void parser_init(void);
extern int base_yyparse(void);
extern List *SystemFuncName(char *name);
extern TypeName *SystemTypeName(char *name);
-extern bool exprIsNullConstant(Node *arg);
#endif /* GRAMPARSE_H */
diff --git a/src/test/regress/expected/domain.out b/src/test/regress/expected/domain.out
index c7d5b503345..b951ce8caa8 100644
--- a/src/test/regress/expected/domain.out
+++ b/src/test/regress/expected/domain.out
@@ -205,7 +205,15 @@ create table defaulttest
, col8 ddef5
);
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "defaulttest_pkey" for table "defaulttest"
-insert into defaulttest default values;
+insert into defaulttest(col4) values(0); -- fails, col5 defaults to null
+ERROR: null value in column "col5" violates not-null constraint
+alter table defaulttest alter column col5 drop default;
+insert into defaulttest default values; -- succeeds, inserts domain default
+-- We used to treat SET DEFAULT NULL as equivalent to DROP DEFAULT; wrong
+alter table defaulttest alter column col5 set default null;
+insert into defaulttest(col4) values(0); -- fails
+ERROR: null value in column "col5" violates not-null constraint
+alter table defaulttest alter column col5 drop default;
insert into defaulttest default values;
insert into defaulttest default values;
-- Test defaults with copy
diff --git a/src/test/regress/sql/domain.sql b/src/test/regress/sql/domain.sql
index 7da99719911..7a4ec383d20 100644
--- a/src/test/regress/sql/domain.sql
+++ b/src/test/regress/sql/domain.sql
@@ -168,7 +168,13 @@ create table defaulttest
, col7 ddef4 DEFAULT 8000
, col8 ddef5
);
-insert into defaulttest default values;
+insert into defaulttest(col4) values(0); -- fails, col5 defaults to null
+alter table defaulttest alter column col5 drop default;
+insert into defaulttest default values; -- succeeds, inserts domain default
+-- We used to treat SET DEFAULT NULL as equivalent to DROP DEFAULT; wrong
+alter table defaulttest alter column col5 set default null;
+insert into defaulttest(col4) values(0); -- fails
+alter table defaulttest alter column col5 drop default;
insert into defaulttest default values;
insert into defaulttest default values;
--
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