Restore the previous semantics of get_constraint_index().

Commit 8b069ef5d changed this function to look at pg_constraint.conindid
rather than searching pg_depend.  That was a good performance improvement,
but it failed to preserve the exact semantics.  The old code would only
return an index that was "owned by" (internally dependent on) the
specified constraint, whereas the new code will also return indexes that
are just referenced by foreign key constraints.  This confuses ALTER
TABLE, which was implicitly expecting the previous semantics, into
failing with errors like
    ERROR:  relation 146621 has multiple clustered indexes
or
    ERROR:  "pk_attbl" is not an index for table "atref"

We can fix this without reverting the performance improvement by adding
a contype check in get_constraint_index().  Another way could be to
make ALTER TABLE check it, but I'm worried that extension code could
also have subtle dependencies on the old semantics.

Tom Lane and Japin Li, per bug #17409 from Holly Roberts.
Back-patch to v14 where the error crept in.

Discussion: https://postgr.es/m/17409-52871dda8b5741cb@postgresql.org

diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index feef99986346bbcf7c433afa0de4ca5e31cb1de8..1b7e11b93e015547b3ec036c8053ea454a5677de 100644 (file)
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -1126,8 +1126,13 @@ get_constraint_name(Oid conoid)
  *             Given the OID of a unique, primary-key, or exclusion constraint,
  *             return the OID of the underlying index.
  *
- * Return InvalidOid if the index couldn't be found; this suggests the
- * given OID is bogus, but we leave it to caller to decide what to do.
+ * Returns InvalidOid if the constraint could not be found or is of
+ * the wrong type.
+ *
+ * The intent of this function is to return the index "owned" by the
+ * specified constraint.  Therefore we must check contype, since some
+ * pg_constraint entries (e.g. for foreign-key constraints) store the
+ * OID of an index that is referenced but not owned by the constraint.
  */
 Oid
 get_constraint_index(Oid conoid)
@@ -1140,7 +1145,12 @@ get_constraint_index(Oid conoid)
                Form_pg_constraint contup = (Form_pg_constraint) GETSTRUCT(tp);
                Oid                     result;
 
-               result = contup->conindid;
+               if (contup->contype == CONSTRAINT_UNIQUE ||
+                       contup->contype == CONSTRAINT_PRIMARY ||
+                       contup->contype == CONSTRAINT_EXCLUSION)
+                       result = contup->conindid;
+               else
+                       result = InvalidOid;
                ReleaseSysCache(tp);
                return result;
        }

diff --git a/src/test/regress/expected/alter_table.out b/src/test/regress/expected/alter_table.out
index 16e047566341acb632e356e09c94826cb3590d5b..aabc564e2c8e9191943a0c9f305dd28ca4da247c 100644 (file)
--- a/src/test/regress/expected/alter_table.out
+++ b/src/test/regress/expected/alter_table.out
@@ -4502,6 +4502,20 @@ create trigger xtrig
 update bar1 set a = a + 1;
 INFO:  a=1, b=1
 /* End test case for bug #16242 */
+/* Test case for bug #17409 */
+create table attbl (p1 int constraint pk_attbl primary key);
+create table atref (c1 int references attbl(p1));
+cluster attbl using pk_attbl;
+alter table attbl alter column p1 set data type bigint;
+alter table atref alter column c1 set data type bigint;
+drop table attbl, atref;
+create table attbl (p1 int constraint pk_attbl primary key);
+alter table attbl replica identity using index pk_attbl;
+create table atref (c1 int references attbl(p1));
+alter table attbl alter column p1 set data type bigint;
+alter table atref alter column c1 set data type bigint;
+drop table attbl, atref;
+/* End test case for bug #17409 */
 -- Test that ALTER TABLE rewrite preserves a clustered index
 -- for normal indexes and indexes on constraints.
 create table alttype_cluster (a int);

diff --git a/src/test/regress/sql/alter_table.sql b/src/test/regress/sql/alter_table.sql
index ac894c0602c6a31e657a45654c978ef87322e33d..cce1cb1dd3c1a19eec9a29df3d91ca750b54b997 100644 (file)
--- a/src/test/regress/sql/alter_table.sql
+++ b/src/test/regress/sql/alter_table.sql
@@ -2958,6 +2958,24 @@ update bar1 set a = a + 1;
 
 /* End test case for bug #16242 */
 
+/* Test case for bug #17409 */
+
+create table attbl (p1 int constraint pk_attbl primary key);
+create table atref (c1 int references attbl(p1));
+cluster attbl using pk_attbl;
+alter table attbl alter column p1 set data type bigint;
+alter table atref alter column c1 set data type bigint;
+drop table attbl, atref;
+
+create table attbl (p1 int constraint pk_attbl primary key);
+alter table attbl replica identity using index pk_attbl;
+create table atref (c1 int references attbl(p1));
+alter table attbl alter column p1 set data type bigint;
+alter table atref alter column c1 set data type bigint;
+drop table attbl, atref;
+
+/* End test case for bug #17409 */
+
 -- Test that ALTER TABLE rewrite preserves a clustered index
 -- for normal indexes and indexes on constraints.
 create table alttype_cluster (a int);