(entry)->xact_depth, (entry)->xact_depth); \
} while(0)
+/*
+ * Extension version number, for supporting older extension versions' objects
+ */
+enum pgfdwVersion
+{
+ PGFDW_V1_1 = 0,
+ PGFDW_V1_2,
+};
+
/*
* SQL functions
*/
PG_FUNCTION_INFO_V1(postgres_fdw_get_connections);
+PG_FUNCTION_INFO_V1(postgres_fdw_get_connections_1_2);
PG_FUNCTION_INFO_V1(postgres_fdw_disconnect);
PG_FUNCTION_INFO_V1(postgres_fdw_disconnect_all);
UserMapping *user, PGconn *conn);
static bool UserMappingPasswordRequired(UserMapping *user);
static bool disconnect_cached_connections(Oid serverid);
+static void postgres_fdw_get_connections_internal(FunctionCallInfo fcinfo,
+ enum pgfdwVersion api_version);
/*
* Get a PGconn which can be used to execute queries on the remote PostgreSQL
}
}
+/* Number of output arguments (columns) for various API versions */
+#define POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_1 2
+#define POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_2 3
+#define POSTGRES_FDW_GET_CONNECTIONS_COLS 3 /* maximum of above */
+
/*
- * List active foreign server connections.
+ * Internal function used by postgres_fdw_get_connections variants.
+ *
+ * For API version 1.1, this function returns a set of records with
+ * the following values:
*
- * This function takes no input parameter and returns setof record made of
- * following values:
* - server_name - server name of active connection. In case the foreign server
* is dropped but still the connection is active, then the server name will
* be NULL in output.
* - valid - true/false representing whether the connection is valid or not.
- * Note that the connections can get invalidated in pgfdw_inval_callback.
+ * Note that connections can become invalid in pgfdw_inval_callback.
+ *
+ * For API version 1.2 and later, this function returns the following
+ * additional value along with the two values from version 1.1:
+ *
+ * - used_in_xact - true if the connection is used in the current transaction.
*
* No records are returned when there are no cached connections at all.
*/
-Datum
-postgres_fdw_get_connections(PG_FUNCTION_ARGS)
+static void
+postgres_fdw_get_connections_internal(FunctionCallInfo fcinfo,
+ enum pgfdwVersion api_version)
{
-#define POSTGRES_FDW_GET_CONNECTIONS_COLS 2
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
HASH_SEQ_STATUS scan;
ConnCacheEntry *entry;
/* If cache doesn't exist, we return no records */
if (!ConnectionHash)
- PG_RETURN_VOID();
+ return;
+
+ /* Check we have the expected number of output arguments */
+ switch (rsinfo->setDesc->natts)
+ {
+ case POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_1:
+ if (api_version != PGFDW_V1_1)
+ elog(ERROR, "incorrect number of output arguments");
+ break;
+ case POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_2:
+ if (api_version != PGFDW_V1_2)
+ elog(ERROR, "incorrect number of output arguments");
+ break;
+ default:
+ elog(ERROR, "incorrect number of output arguments");
+ }
hash_seq_init(&scan, ConnectionHash);
while ((entry = (ConnCacheEntry *) hash_seq_search(&scan)))
values[1] = BoolGetDatum(!entry->invalidated);
+ if (api_version >= PGFDW_V1_2)
+ {
+ /* Is this connection used in the current transaction? */
+ values[2] = BoolGetDatum(entry->xact_depth > 0);
+ }
+
tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
}
+}
+
+/*
+ * List active foreign server connections.
+ *
+ * The SQL API of this function has changed multiple times, and will likely
+ * do so again in future. To support the case where a newer version of this
+ * loadable module is being used with an old SQL declaration of the function,
+ * we continue to support the older API versions.
+ */
+Datum
+postgres_fdw_get_connections_1_2(PG_FUNCTION_ARGS)
+{
+ postgres_fdw_get_connections_internal(fcinfo, PGFDW_V1_2);
+
+ PG_RETURN_VOID();
+}
+
+Datum
+postgres_fdw_get_connections(PG_FUNCTION_ARGS)
+{
+ postgres_fdw_get_connections_internal(fcinfo, PGFDW_V1_1);
PG_RETURN_VOID();
}
<variablelist>
<varlistentry>
- <term><function>postgres_fdw_get_connections(OUT server_name text, OUT valid boolean) returns setof record</function></term>
+ <term><function>postgres_fdw_get_connections(OUT server_name text,
+ OUT valid boolean, OUT used_in_xact boolean)
+ returns setof record</function></term>
<listitem>
<para>
This function returns information about all open connections postgres_fdw
no open connections, no records are returned.
Example usage of the function:
<screen>
-postgres=# SELECT * FROM postgres_fdw_get_connections() ORDER BY 1;
- server_name | valid
--------------+-------
- loopback1 | t
- loopback2 | f
+postgres=*# SELECT * FROM postgres_fdw_get_connections() ORDER BY 1;
+ server_name | valid | used_in_xact
+-------------+-------+--------------
+ loopback1 | t | t
+ loopback2 | f | t
</screen>
The output columns are described in
<xref linkend="postgres-fdw-get-connections-columns"/>.
the transaction. True is returned otherwise.
</entry>
</row>
+ <row>
+ <entry><structfield>used_in_xact</structfield></entry>
+ <entry><type>boolean</type></entry>
+ <entry>
+ True if this connection is used in the current transaction.
+ </entry>
+ </row>
</tbody>
</tgroup>
</table>
projects / postgresql.git / commitdiff