Make ALTER TABLE revalidate uniqueness and exclusion constraints.

Failure to do so can lead to constraint violations.  This was broken by
commit 1ddc2703a936d03953657f43345460b9242bbed1 on 2010-02-07, so
back-patch to 9.0.

Noah Misch.  Regression test by me.

2 files changed, 6 insertions, 0 deletions

diff --git a/src/test/regress/expected/alter_table.out b/src/test/regress/expected/alter_table.out
index 3d126bbf308..3280065f75b 100644
--- a/src/test/regress/expected/alter_table.out
+++ b/src/test/regress/expected/alter_table.out
@@ -413,6 +413,10 @@ insert into atacc1 (test) values (4);
 -- try adding a unique oid constraint
 alter table atacc1 add constraint atacc_oid1 unique(oid);
 NOTICE:  ALTER TABLE / ADD UNIQUE will create implicit index "atacc_oid1" for table "atacc1"
+-- try to create duplicates via alter table using - should fail
+alter table atacc1 alter column test type integer using 0;
+ERROR:  could not create unique index "atacc_test1"
+DETAIL:  Key (test)=(0) is duplicated.
 drop table atacc1;
 -- let's do one where the unique constraint fails when added
 create table atacc1 ( test int );
diff --git a/src/test/regress/sql/alter_table.sql b/src/test/regress/sql/alter_table.sql
index 4895768d7fe..cfbfbb6b438 100644
--- a/src/test/regress/sql/alter_table.sql
+++ b/src/test/regress/sql/alter_table.sql
@@ -419,6 +419,8 @@ insert into atacc1 (test) values (2);
 insert into atacc1 (test) values (4);
 -- try adding a unique oid constraint
 alter table atacc1 add constraint atacc_oid1 unique(oid);
+-- try to create duplicates via alter table using - should fail
+alter table atacc1 alter column test type integer using 0;
 drop table atacc1;
 
 -- let's do one where the unique constraint fails when added