Logical replication

- Add PUBLICATION catalogs and DDL
- Add SUBSCRIPTION catalog and DDL
- Define logical replication protocol and output plugin
- Add logical replication workers

From: Petr Jelinek <petr@2ndquadrant.com>
Reviewed-by: Steve Singer <steve@ssinger.info>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Erik Rijkers <er@xs4all.nl>
Reviewed-by: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>

3 files changed, 37 insertions, 1 deletions

diff --git a/src/backend/postmaster/bgworker.c b/src/backend/postmaster/bgworker.c
index 61d3170b839..cd99b0b3927 100644
--- a/src/backend/postmaster/bgworker.c
+++ b/src/backend/postmaster/bgworker.c
@@ -20,6 +20,7 @@
 #include "port/atomics.h"
 #include "postmaster/bgworker_internals.h"
 #include "postmaster/postmaster.h"
+#include "replication/logicallauncher.h"
 #include "storage/dsm.h"
 #include "storage/ipc.h"
 #include "storage/latch.h"
@@ -108,6 +109,15 @@ struct BackgroundWorkerHandle
 static BackgroundWorkerArray *BackgroundWorkerData;
 
 /*
+ * List of workers that are allowed to be started outside of
+ * shared_preload_libraries.
+ */
+static const bgworker_main_type InternalBGWorkers[] = {
+	ApplyLauncherMain,
+	NULL
+};
+
+/*
  * Calculate shared memory needed.
  */
 Size
@@ -761,12 +771,23 @@ RegisterBackgroundWorker(BackgroundWorker *worker)
 {
 	RegisteredBgWorker *rw;
 	static int	numworkers = 0;
+	bool		internal = false;
+	int			i;
 
 	if (!IsUnderPostmaster)
 		ereport(DEBUG1,
 		 (errmsg("registering background worker \"%s\"", worker->bgw_name)));
 
-	if (!process_shared_preload_libraries_in_progress)
+	for (i = 0; InternalBGWorkers[i]; i++)
+	{
+		if (worker->bgw_main == InternalBGWorkers[i])
+		{
+			internal = true;
+			break;
+		}
+	}
+
+	if (!process_shared_preload_libraries_in_progress && !internal)
 	{
 		if (!IsUnderPostmaster)
 			ereport(LOG,
diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index f37a0bfaafd..7176cf1bbeb 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -3303,6 +3303,12 @@ pgstat_get_wait_activity(WaitEventActivity w)
 		case WAIT_EVENT_WAL_WRITER_MAIN:
 			event_name = "WalWriterMain";
 			break;
+		case WAIT_EVENT_LOGICAL_LAUNCHER_MAIN:
+			event_name = "LogicalLauncherMain";
+			break;
+		case WAIT_EVENT_LOGICAL_APPLY_MAIN:
+			event_name = "LogicalApplyMain";
+			break;
 		/* no default case, so that compiler will warn */
 	}
 
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 5be30b0ee15..8d99c7a0d4e 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -113,6 +113,7 @@
 #include "postmaster/pgarch.h"
 #include "postmaster/postmaster.h"
 #include "postmaster/syslogger.h"
+#include "replication/logicallauncher.h"
 #include "replication/walsender.h"
 #include "storage/fd.h"
 #include "storage/ipc.h"
@@ -942,6 +943,14 @@ PostmasterMain(int argc, char *argv[])
 #endif
 
 	/*
+	 * Register the apply launcher.  Since it registers a background worker,
+	 * it needs to be called before InitializeMaxBackends(), and it's probably
+	 * a good idea to call it before any modules had chance to take the
+	 * background worker slots.
+	 */
+	ApplyLauncherRegister();
+
+	/*
 	 * process any libraries that should be preloaded at postmaster start
 	 */
 	process_shared_preload_libraries();