Correctly init/deinit recovery xact environment.

Previously we performed VirtualXactLockTableInsert
but didn't set MyProc->lxid for Startup process.
pg_locks now correctly shows "1/1" for vxid
of Startup process during Hot Standby.
At end of Hot Standby the Virtual Transaction
was not deleted, leading to problems after
promoting to normal running for some commands,
such as CREATE INDEX CONCURRENTLY.

src/backend/storage/ipc/standby.c

@@ -81,7 +81,7 @@ InitRecoveryTransactionEnvironment(void)
 	 * hold AccessShareLocks so never block while we write or lock new rows.
 	 */
 	vxid.backendId = MyBackendId;
-	vxid.localTransactionId = GetNextLocalTransactionId();
+	vxid.localTransactionId = MyProc->lxid = GetNextLocalTransactionId();
 	VirtualXactLockTableInsert(vxid);
 
 	standbyState = STANDBY_INITIALIZED;
@@ -97,11 +97,18 @@ InitRecoveryTransactionEnvironment(void)
 void
 ShutdownRecoveryTransactionEnvironment(void)
 {
+	VirtualTransactionId vxid;
+
 	/* Mark all tracked in-progress transactions as finished. */
 	ExpireAllKnownAssignedTransactionIds();
 
 	/* Release all locks the tracked transactions were holding */
 	StandbyReleaseAllLocks();
+
+	/* Cleanup our VirtualTransaction */
+	vxid.backendId = MyBackendId;
+	vxid.localTransactionId = MyProc->lxid;
+	VirtualXactLockTableDelete(vxid);
 }
 
 

src/backend/storage/lmgr/lmgr.c

@@ -534,6 +534,24 @@ VirtualXactLockTableInsert(VirtualTransactionId vxid)
 	(void) LockAcquire(&tag, ExclusiveLock, false, false);
 }
 
+/*
+ *		VirtualXactLockTableDelete
+ *
+ * Release a Virtual Transaction lock. Only called by Startup process
+ * at end of Hot Standby.
+ */
+void
+VirtualXactLockTableDelete(VirtualTransactionId vxid)
+{
+	LOCKTAG		tag;
+
+	Assert(VirtualTransactionIdIsValid(vxid));
+
+	SET_LOCKTAG_VIRTUALTRANSACTION(tag, vxid);
+
+	(void) LockRelease(&tag, ExclusiveLock, false);
+}
+
 /*
  *		VirtualXactLockTableWait
  *

src/include/storage/lmgr.h

@@ -58,6 +58,7 @@ extern bool ConditionalXactLockTableWait(TransactionId xid);
 
 /* Lock a VXID (used to wait for a transaction to finish) */
 extern void VirtualXactLockTableInsert(VirtualTransactionId vxid);
+extern void VirtualXactLockTableDelete(VirtualTransactionId vxid);
 extern void VirtualXactLockTableWait(VirtualTransactionId vxid);
 extern bool ConditionalVirtualXactLockTableWait(VirtualTransactionId vxid);