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DROP IF EXISTS for columns and constraints. Andres Freund.

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REL8_5_ALPHA1_BRANCH
Andrew Dunstan 16 years ago
parent 31d1f23302
commit e73131a16a
8 changed files with 111 additions and 32 deletions
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  1. 15
      doc/src/sgml/ref/alter_table.sgml
  2. 58
      src/backend/commands/tablecmds.c
  3. 3
      src/backend/nodes/copyfuncs.c
  4. 3
      src/backend/nodes/equalfuncs.c
  5. 24
      src/backend/parser/gram.y
  6. 3
      src/include/nodes/parsenodes.h
  7. 10
      src/test/regress/expected/alter_table.out
  8. 9
      src/test/regress/sql/alter_table.sql

15
doc/src/sgml/ref/alter_table.sgml
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@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.106 2009/05/03 20:45:43 tgl Exp $
$PostgreSQL: pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.107 2009/07/20 02:42:27 adunstan Exp $
PostgreSQL documentation
-->
@ -33,7 +33,7 @@ ALTER TABLE <replaceable class="PARAMETER">name</replaceable>
where <replaceable class="PARAMETER">action</replaceable> is one of:
ADD [ COLUMN ] <replaceable class="PARAMETER">column</replaceable> <replaceable class="PARAMETER">type</replaceable> [ <replaceable class="PARAMETER">column_constraint</replaceable> [ ... ] ]
DROP [ COLUMN ] <replaceable class="PARAMETER">column</replaceable> [ RESTRICT | CASCADE ]
DROP [ COLUMN ] [ IF EXISTS ] <replaceable class="PARAMETER">column</replaceable> [ RESTRICT | CASCADE ]
ALTER [ COLUMN ] <replaceable class="PARAMETER">column</replaceable> [ SET DATA ] TYPE <replaceable class="PARAMETER">type</replaceable> [ USING <replaceable class="PARAMETER">expression</replaceable> ]
ALTER [ COLUMN ] <replaceable class="PARAMETER">column</replaceable> SET DEFAULT <replaceable class="PARAMETER">expression</replaceable>
ALTER [ COLUMN ] <replaceable class="PARAMETER">column</replaceable> DROP DEFAULT
@ -41,7 +41,7 @@ where <replaceable class="PARAMETER">action</replaceable> is one of:
ALTER [ COLUMN ] <replaceable class="PARAMETER">column</replaceable> SET STATISTICS <replaceable class="PARAMETER">integer</replaceable>
ALTER [ COLUMN ] <replaceable class="PARAMETER">column</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
ADD <replaceable class="PARAMETER">table_constraint</replaceable>
DROP CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable> [ RESTRICT | CASCADE ]
DROP CONSTRAINT [ IF EXISTS ] <replaceable class="PARAMETER">constraint_name</replaceable> [ RESTRICT | CASCADE ]
DISABLE TRIGGER [ <replaceable class="PARAMETER">trigger_name</replaceable> | ALL | USER ]
ENABLE TRIGGER [ <replaceable class="PARAMETER">trigger_name</replaceable> | ALL | USER ]
ENABLE REPLICA TRIGGER <replaceable class="PARAMETER">trigger_name</replaceable>
@ -82,7 +82,7 @@ where <replaceable class="PARAMETER">action</replaceable> is one of:
</varlistentry>
<varlistentry>
<term><literal>DROP COLUMN</literal></term>
<term><literal>DROP COLUMN [ IF EXISTS ]</literal></term>
<listitem>
<para>
This form drops a column from a table. Indexes and
@ -90,6 +90,9 @@ where <replaceable class="PARAMETER">action</replaceable> is one of:
dropped as well. You will need to say <literal>CASCADE</> if
anything outside the table depends on the column, for example,
foreign key references or views.
If <literal>IF EXISTS</literal> is specified and the column
does not exist, no error is thrown. In this case a notice
is issued instead.
</para>
</listitem>
</varlistentry>
@ -192,10 +195,12 @@ where <replaceable class="PARAMETER">action</replaceable> is one of:
</varlistentry>
<varlistentry>
<term><literal>DROP CONSTRAINT</literal></term>
<term><literal>DROP CONSTRAINT [ IF EXISTS ]</literal></term>
<listitem>
<para>
This form drops the specified constraint on a table.
If <literal>IF EXISTS</literal> is specified and the constraint
does not exist, no error is thrown. In this case a notice is issued instead.
</para>
</listitem>
</varlistentry>

58
src/backend/commands/tablecmds.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.290 2009/07/16 06:33:42 petere Exp $
* $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.291 2009/07/20 02:42:27 adunstan Exp $
*
*-------------------------------------------------------------------------
*/
@ -285,7 +285,8 @@ static void ATExecSetStorage(Relation rel, const char *colName,
Node *newValue);
static void ATExecDropColumn(List **wqueue, Relation rel, const char *colName,
DropBehavior behavior,
bool recurse, bool recursing);
bool recurse, bool recursing,
bool missing_ok);
static void ATExecAddIndex(AlteredTableInfo *tab, Relation rel,
IndexStmt *stmt, bool is_rebuild);
static void ATExecAddConstraint(List **wqueue,
@ -299,7 +300,8 @@ static void ATAddForeignKeyConstraint(AlteredTableInfo *tab, Relation rel,
FkConstraint *fkconstraint);
static void ATExecDropConstraint(Relation rel, const char *constrName,
DropBehavior behavior,
bool recurse, bool recursing);
bool recurse, bool recursing,
bool missing_ok);
static void ATPrepAlterColumnType(List **wqueue,
AlteredTableInfo *tab, Relation rel,
bool recurse, bool recursing,
@ -2620,11 +2622,11 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
break;
case AT_DropColumn: /* DROP COLUMN */
ATExecDropColumn(wqueue, rel, cmd->name,
cmd->behavior, false, false);
cmd->behavior, false, false, cmd->missing_ok);
break;
case AT_DropColumnRecurse: /* DROP COLUMN with recursion */
ATExecDropColumn(wqueue, rel, cmd->name,
cmd->behavior, true, false);
cmd->behavior, true, false, cmd->missing_ok);
break;
case AT_AddIndex: /* ADD INDEX */
ATExecAddIndex(tab, rel, (IndexStmt *) cmd->def, false);
@ -2639,10 +2641,14 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
ATExecAddConstraint(wqueue, tab, rel, cmd->def, true);
break;
case AT_DropConstraint: /* DROP CONSTRAINT */
ATExecDropConstraint(rel, cmd->name, cmd->behavior, false, false);
ATExecDropConstraint(rel, cmd->name, cmd->behavior,
false, false,
cmd->missing_ok);
break;
case AT_DropConstraintRecurse: /* DROP CONSTRAINT with recursion */
ATExecDropConstraint(rel, cmd->name, cmd->behavior, true, false);
ATExecDropConstraint(rel, cmd->name, cmd->behavior,
true, false,
cmd->missing_ok);
break;
case AT_AlterColumnType: /* ALTER COLUMN TYPE */
ATExecAlterColumnType(tab, rel, cmd->name, (TypeName *) cmd->def);
@ -4160,7 +4166,8 @@ ATExecSetStorage(Relation rel, const char *colName, Node *newValue)
static void
ATExecDropColumn(List **wqueue, Relation rel, const char *colName,
DropBehavior behavior,
bool recurse, bool recursing)
bool recurse, bool recursing,
bool missing_ok)
{
HeapTuple tuple;
Form_pg_attribute targetatt;
@ -4176,11 +4183,21 @@ ATExecDropColumn(List **wqueue, Relation rel, const char *colName,
* get the number of the attribute
*/
tuple = SearchSysCacheAttName(RelationGetRelid(rel), colName);
if (!HeapTupleIsValid(tuple))
if (!HeapTupleIsValid(tuple)){
if (!missing_ok){
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_COLUMN),
errmsg("column \"%s\" of relation \"%s\" does not exist",
colName, RelationGetRelationName(rel))));
}
else
{
ereport(NOTICE,
(errmsg("column \"%s\" of relation \"%s\" does not exist, skipping",
colName, RelationGetRelationName(rel))));
return;
}
}
targetatt = (Form_pg_attribute) GETSTRUCT(tuple);
attnum = targetatt->attnum;
@ -4246,7 +4263,8 @@ ATExecDropColumn(List **wqueue, Relation rel, const char *colName,
{
/* Time to delete this child column, too */
ATExecDropColumn(wqueue, childrel, colName,
behavior, true, true);
behavior, true, true,
false);
}
else
{
@ -5360,7 +5378,8 @@ createForeignKeyTriggers(Relation rel, FkConstraint *fkconstraint,
static void
ATExecDropConstraint(Relation rel, const char *constrName,
DropBehavior behavior,
bool recurse, bool recursing)
bool recurse, bool recursing,
bool missing_ok)
{
List *children;
ListCell *child;
@ -5422,12 +5441,22 @@ ATExecDropConstraint(Relation rel, const char *constrName,
systable_endscan(scan);
if (!found)
if (!found){
if (!missing_ok){
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("constraint \"%s\" of relation \"%s\" does not exist",
constrName, RelationGetRelationName(rel))));
}
else
{
ereport(NOTICE,
(errmsg("constraint \"%s\" of relation \"%s\" does not exist, skipping",
constrName, RelationGetRelationName(rel))));
heap_close(conrel, RowExclusiveLock);
return;
}
}
/*
* Propagate to children as appropriate. Unlike most other ALTER
* routines, we have to do this one level of recursion at a time; we can't
@ -5490,7 +5519,8 @@ ATExecDropConstraint(Relation rel, const char *constrName,
{
/* Time to delete this child constraint, too */
ATExecDropConstraint(childrel, constrName, behavior,
true, true);
true, true,
false);
}
else
{

3
src/backend/nodes/copyfuncs.c
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@ -15,7 +15,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.433 2009/07/16 06:33:42 petere Exp $
* $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.434 2009/07/20 02:42:27 adunstan Exp $
*
*-------------------------------------------------------------------------
*/
@ -2272,6 +2272,7 @@ _copyAlterTableCmd(AlterTableCmd *from)
COPY_NODE_FIELD(def);
COPY_NODE_FIELD(transform);
COPY_SCALAR_FIELD(behavior);
COPY_SCALAR_FIELD(missing_ok);
return newnode;
}

3
src/backend/nodes/equalfuncs.c
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@ -22,7 +22,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.356 2009/07/16 06:33:42 petere Exp $
* $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.357 2009/07/20 02:42:27 adunstan Exp $
*
*-------------------------------------------------------------------------
*/
@ -958,6 +958,7 @@ _equalAlterTableCmd(AlterTableCmd *a, AlterTableCmd *b)
COMPARE_NODE_FIELD(def);
COMPARE_NODE_FIELD(transform);
COMPARE_SCALAR_FIELD(behavior);
COMPARE_SCALAR_FIELD(missing_ok);
return true;
}

24
src/backend/parser/gram.y
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@ -11,7 +11,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.670 2009/07/16 06:33:43 petere Exp $
* $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.671 2009/07/20 02:42:28 adunstan Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
@ -1610,6 +1610,16 @@ alter_table_cmd:
n->def = (Node *) makeString($6);
$$ = (Node *)n;
}
/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
{
AlterTableCmd *n = makeNode(AlterTableCmd);
n->subtype = AT_DropColumn;
n->name = $5;
n->behavior = $6;
n->missing_ok = TRUE;
$$ = (Node *)n;
}
/* ALTER TABLE <name> DROP [COLUMN] <colname> [RESTRICT|CASCADE] */
| DROP opt_column ColId opt_drop_behavior
{
@ -1617,6 +1627,7 @@ alter_table_cmd:
n->subtype = AT_DropColumn;
n->name = $3;
n->behavior = $4;
n->missing_ok = FALSE;
$$ = (Node *)n;
}
/*
@ -1640,6 +1651,16 @@ alter_table_cmd:
n->def = $2;
$$ = (Node *)n;
}
/* ALTER TABLE <name> DROP CONSTRAINT IF EXISTS <name> [RESTRICT|CASCADE] */
| DROP CONSTRAINT IF_P EXISTS name opt_drop_behavior
{
AlterTableCmd *n = makeNode(AlterTableCmd);
n->subtype = AT_DropConstraint;
n->name = $5;
n->behavior = $6;
n->missing_ok = TRUE;
$$ = (Node *)n;
}
/* ALTER TABLE <name> DROP CONSTRAINT <name> [RESTRICT|CASCADE] */
| DROP CONSTRAINT name opt_drop_behavior
{
@ -1647,6 +1668,7 @@ alter_table_cmd:
n->subtype = AT_DropConstraint;
n->name = $3;
n->behavior = $4;
n->missing_ok = FALSE;
$$ = (Node *)n;
}
/* ALTER TABLE <name> SET WITH OIDS */

3
src/include/nodes/parsenodes.h
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@ -13,7 +13,7 @@
* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.396 2009/07/16 06:33:45 petere Exp $
* $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.397 2009/07/20 02:42:28 adunstan Exp $
*
*-------------------------------------------------------------------------
*/
@ -1145,6 +1145,7 @@ typedef struct AlterTableCmd /* one subcommand of an ALTER TABLE */
* index, constraint, or parent table */
Node *transform; /* transformation expr for ALTER TYPE */
DropBehavior behavior; /* RESTRICT or CASCADE for DROP cases */
bool missing_ok; /* skip error if missing? */
} AlterTableCmd;

10
src/test/regress/expected/alter_table.out
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@ -1150,6 +1150,12 @@ alter table gc1 drop column name;
ERROR: column "name" of relation "gc1" does not exist
-- should work and drop the attribute in all tables
alter table p2 drop column height;
-- IF EXISTS test
create table dropColumnExists ();
alter table dropColumnExists drop column non_existing; --fail
ERROR: column "non_existing" of relation "dropcolumnexists" does not exist
alter table dropColumnExists drop column if exists non_existing; --succeed
NOTICE: column "non_existing" of relation "dropcolumnexists" does not exist, skipping
select relname, attname, attinhcount, attislocal
from pg_class join pg_attribute on (pg_class.oid = pg_attribute.attrelid)
where relname in ('p1','p2','c1','gc1') and attnum > 0 and not attisdropped
@ -1421,6 +1427,10 @@ alter table anothertab alter column atcol1 type boolean
ERROR: operator does not exist: boolean <= integer
HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts.
alter table anothertab drop constraint anothertab_chk;
alter table anothertab drop constraint anothertab_chk; -- fails
ERROR: constraint "anothertab_chk" of relation "anothertab" does not exist
alter table anothertab drop constraint IF EXISTS anothertab_chk; -- succeeds
NOTICE: constraint "anothertab_chk" of relation "anothertab" does not exist, skipping
alter table anothertab alter column atcol1 type boolean
using case when atcol1 % 2 = 0 then true else false end;
select * from anothertab;

9
src/test/regress/sql/alter_table.sql
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@ -816,6 +816,8 @@ create table dropColumnAnother (d int) inherits (dropColumnChild);
alter table dropColumnchild drop column a;
alter table only dropColumnChild drop column b;
-- these three should work
alter table only dropColumn drop column e;
alter table dropColumnChild drop column c;
@ -913,6 +915,11 @@ alter table gc1 drop column name;
-- should work and drop the attribute in all tables
alter table p2 drop column height;
-- IF EXISTS test
create table dropColumnExists ();
alter table dropColumnExists drop column non_existing; --fail
alter table dropColumnExists drop column if exists non_existing; --succeed
select relname, attname, attinhcount, attislocal
from pg_class join pg_attribute on (pg_class.oid = pg_attribute.attrelid)
where relname in ('p1','p2','c1','gc1') and attnum > 0 and not attisdropped
@ -1057,6 +1064,8 @@ alter table anothertab alter column atcol1 drop default;
alter table anothertab alter column atcol1 type boolean
using case when atcol1 % 2 = 0 then true else false end; -- fails
alter table anothertab drop constraint anothertab_chk;
alter table anothertab drop constraint anothertab_chk; -- fails
alter table anothertab drop constraint IF EXISTS anothertab_chk; -- succeeds
alter table anothertab alter column atcol1 type boolean
using case when atcol1 % 2 = 0 then true else false end;

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