Metadata queries improvment (#1694)

* Metadata queries improvements.
When dealing with large PostrgeSQL databases of thousands of schemas, tens of thousands of tables and millions of indexes particular PgDatabaseMetaData methods have suboptimal implementation.
The pattern that was utilized in implementation used inner query on pg_catalog.pg_index in order to retrieve keys (information_schema._pg_expandarray(i.indkey) AS keys). Such implementation forced full table scan on pg_catalog.pg_index prior to filtering result set on schema and table name.
The optimization idea was to get rid of inner querry in order to let querry planner to avoid full table scan and filter out pg_catalog.pg_index rows prior to executing (information_schema._pg_expandarray(i.indkey) AS keys).

* Add test for column order.

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

@@ -2424,6 +2424,7 @@ public ResultSet getIndexInfo(String catalog, String schema, String tableName,
       }
 
       sql = "SELECT "
+                + "    tmp.TABLE_CAT, "
                 + "    tmp.TABLE_SCHEM, "
                 + "    tmp.TABLE_NAME, "
                 + "    tmp.NON_UNIQUE, "

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

@@ -658,6 +658,32 @@ public void testIndexInfo() throws SQLException {
     rs.close();
   }
 
+  /**
+   * Order defined at
+   * https://docs.oracle.com/javase/8/docs/api/java/sql/DatabaseMetaData.html#getIndexInfo-java.lang.String-java.lang.String-java.lang.String-boolean-boolean-
+   */
+  @Test
+  public void testIndexInfoColumnOrder() throws SQLException {
+    DatabaseMetaData dbmd = con.getMetaData();
+    assertNotNull(dbmd);
+    ResultSet rs = dbmd.getIndexInfo(null, null, "metadatatest", false, false);
+    assertEquals(rs.findColumn("TABLE_CAT"), 1);
+    assertEquals(rs.findColumn("TABLE_SCHEM"), 2);
+    assertEquals(rs.findColumn("TABLE_NAME"), 3);
+    assertEquals(rs.findColumn("NON_UNIQUE"), 4);
+    assertEquals(rs.findColumn("INDEX_QUALIFIER"), 5);
+    assertEquals(rs.findColumn("INDEX_NAME"), 6);
+    assertEquals(rs.findColumn("TYPE"), 7);
+    assertEquals(rs.findColumn("ORDINAL_POSITION"), 8);
+    assertEquals(rs.findColumn("COLUMN_NAME"), 9);
+    assertEquals(rs.findColumn("ASC_OR_DESC"), 10);
+    assertEquals(rs.findColumn("CARDINALITY"), 11);
+    assertEquals(rs.findColumn("PAGES"), 12);
+    assertEquals(rs.findColumn("FILTER_CONDITION"), 13);
+
+    rs.close();
+  }
+
   @Test
   public void testNotNullDomainColumn() throws SQLException {
     DatabaseMetaData dbmd = con.getMetaData();