4 files changed, 27 insertions, 8 deletions
diff --git a/src/backend/utils/init/globals.c b/src/backend/utils/init/globals.c
index 4b66bd3e358..8dd2b4b1234 100644
--- a/src/backend/utils/init/globals.c
+++ b/src/backend/utils/init/globals.c
@@ -87,6 +87,7 @@ pid_t		PostmasterPid = 0;
 bool		IsPostmasterEnvironment = false;
 bool		IsUnderPostmaster = false;
 bool		IsBinaryUpgrade = false;
+bool		IsBackgroundWorker = false;
 
 bool		ExitOnAnyError = false;
 
diff --git a/src/backend/utils/init/miscinit.c b/src/backend/utils/init/miscinit.c
index 5288aa77ee1..c518c2133cd 100644
--- a/src/backend/utils/init/miscinit.c
+++ b/src/backend/utils/init/miscinit.c
@@ -498,10 +498,10 @@ void
 InitializeSessionUserIdStandalone(void)
 {
 	/*
-	 * This function should only be called in single-user mode and in
-	 * autovacuum workers.
+	 * This function should only be called in single-user mode, in
+	 * autovacuum workers, and in background workers.
 	 */
-	AssertState(!IsUnderPostmaster || IsAutoVacuumWorkerProcess());
+	AssertState(!IsUnderPostmaster || IsAutoVacuumWorkerProcess() || IsBackgroundWorker);
 
 	/* call only once */
 	AssertState(!OidIsValid(AuthenticatedUserId));
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index 2eb456df45e..b87ec6c4822 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -627,6 +627,19 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 					 errhint("You should immediately run CREATE USER \"%s\" SUPERUSER;.",
 							 username)));
 	}
+	else if (IsBackgroundWorker)
+	{
+		if (username == NULL)
+		{
+			InitializeSessionUserIdStandalone();
+			am_superuser = true;
+		}
+		else
+		{
+			InitializeSessionUserId(username);
+			am_superuser = superuser();
+		}
+	}
 	else
 	{
 		/* normal multiuser case */
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 81cf136937c..2cf34cea5a4 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -52,6 +52,7 @@
 #include "parser/scansup.h"
 #include "pgstat.h"
 #include "postmaster/autovacuum.h"
+#include "postmaster/bgworker.h"
 #include "postmaster/bgwriter.h"
 #include "postmaster/postmaster.h"
 #include "postmaster/syslogger.h"
@@ -108,7 +109,8 @@
  * removed, we still could not exceed INT_MAX/4 because some places compute
  * 4*MaxBackends without any overflow check.  This is rechecked in
  * check_maxconnections, since MaxBackends is computed as MaxConnections
- * plus autovacuum_max_workers plus one (for the autovacuum launcher).
+ * plus the number of bgworkers plus autovacuum_max_workers plus one (for the
+ * autovacuum launcher).
  */
 #define MAX_BACKENDS	0x7fffff
 
@@ -8628,7 +8630,8 @@ show_tcp_keepalives_count(void)
 static bool
 check_maxconnections(int *newval, void **extra, GucSource source)
 {
-	if (*newval + autovacuum_max_workers + 1 > MAX_BACKENDS)
+	if (*newval + GetNumShmemAttachedBgworkers() + autovacuum_max_workers + 1 >
+		MAX_BACKENDS)
 		return false;
 	return true;
 }
@@ -8636,13 +8639,15 @@ check_maxconnections(int *newval, void **extra, GucSource source)
 static void
 assign_maxconnections(int newval, void *extra)
 {
-	MaxBackends = newval + autovacuum_max_workers + 1;
+	MaxBackends = newval + autovacuum_max_workers + 1 +
+		GetNumShmemAttachedBgworkers();
 }
 
 static bool
 check_autovacuum_max_workers(int *newval, void **extra, GucSource source)
 {
-	if (MaxConnections + *newval + 1 > MAX_BACKENDS)
+	if (MaxConnections + *newval + 1 + GetNumShmemAttachedBgworkers() >
+		MAX_BACKENDS)
 		return false;
 	return true;
 }
@@ -8650,7 +8655,7 @@ check_autovacuum_max_workers(int *newval, void **extra, GucSource source)
 static void
 assign_autovacuum_max_workers(int newval, void *extra)
 {
-	MaxBackends = MaxConnections + newval + 1;
+	MaxBackends = MaxConnections + newval + 1 + GetNumShmemAttachedBgworkers();
 }
 
 static bool