backpatch pr#2245 fixes case where duplicate tables are returned if t…

…here are duplicate descriptions oids are not guaranteed to be unique in the catalog (#2248)

pgjdbc/src/main/java/org/postgresql/jdbc/PgDatabaseMetaData.java

@@ -1311,9 +1311,7 @@ public ResultSet getTables(@Nullable String catalog, @Nullable String schemaPatt
              + " '' as TYPE_CAT, '' as TYPE_SCHEM, '' as TYPE_NAME, "
              + "'' AS SELF_REFERENCING_COL_NAME, '' AS REF_GENERATION "
              + " FROM pg_catalog.pg_namespace n, pg_catalog.pg_class c "
-             + " LEFT JOIN pg_catalog.pg_description d ON (c.oid = d.objoid AND d.objsubid = 0) "
-             + " LEFT JOIN pg_catalog.pg_class dc ON (d.classoid=dc.oid AND dc.relname='pg_class') "
-             + " LEFT JOIN pg_catalog.pg_namespace dn ON (dn.oid=dc.relnamespace AND dn.nspname='pg_catalog') "
+             + " LEFT JOIN pg_catalog.pg_description d ON (c.oid = d.objoid AND d.objsubid = 0  and d.classoid = 'pg_class'::regclass) "
              + " WHERE c.relnamespace = n.oid ";
 
     if (schemaPattern != null && !schemaPattern.isEmpty()) {

pgjdbc/src/test/java/org/postgresql/test/jdbc2/DatabaseMetaDataTest.java

@@ -64,6 +64,7 @@ public static Iterable<Object[]> data() {
 
   @Before
   public void setUp() throws Exception {
+    Connection conPriv = TestUtil.openPrivilegedDB();
     if (binaryMode == BinaryMode.FORCE) {
       final Properties props = new Properties();
       PGProperty.PREPARE_THRESHOLD.set(props, -1);
@@ -87,6 +88,13 @@ public void setUp() throws Exception {
     TestUtil.createCompositeType(con, "custom", "i int", false);
     TestUtil.createCompositeType(con, "_custom", "f float", false);
 
+    // create a table and multiple comments on it
+    TestUtil.createTable(con, "duplicate", "x text");
+    TestUtil.execute("comment on table duplicate is 'duplicate table'", con);
+    TestUtil.execute("create or replace function bar() returns integer language sql as $$ select 1 $$", con);
+    TestUtil.execute("comment on function bar is 'bar function'", con);
+    TestUtil.execute("update pg_description set objoid = 'duplicate'::regclass where objoid = 'bar'::regproc",conPriv);
+
     // 8.2 does not support arrays of composite types
     TestUtil.createTable(con, "customtable", "c1 custom, c2 _custom"
         + (TestUtil.haveMinimumServerVersion(con, ServerVersion.v8_3) ? ", c3 custom[], c4 _custom[]" : ""));
@@ -125,6 +133,8 @@ public void tearDown() throws Exception {
     // metadatatest table's type
     Statement stmt = con.createStatement();
     stmt.execute("DROP FUNCTION f4(int)");
+    TestUtil.execute("drop function bar()", con);
+    TestUtil.dropTable(con, "duplicate");
 
     TestUtil.dropView(con, "viewtest");
     TestUtil.dropTable(con, "metadatatest");