8 files changed, 47 insertions, 3 deletions

diff --git a/doc/src/sgml/ref/create_database.sgml b/doc/src/sgml/ref/create_database.sgml
index cf33746c1e2..cf0d53b3014 100644
--- a/doc/src/sgml/ref/create_database.sgml
+++ b/doc/src/sgml/ref/create_database.sgml
@@ -258,7 +258,8 @@ CREATE DATABASE <replaceable class="PARAMETER">name</replaceable>
    The <literal>CONNECTION LIMIT</> option is only enforced approximately;
    if two new sessions start at about the same time when just one
    connection <quote>slot</> remains for the database, it is possible that
-   both will fail.  Also, the limit is not enforced against superusers.
+   both will fail.  Also, the limit is not enforced against superusers or
+   background worker processes.
   </para>
  </refsect1>
 
diff --git a/doc/src/sgml/ref/create_role.sgml b/doc/src/sgml/ref/create_role.sgml
index a3b8ed9ab4c..2ae576ede69 100644
--- a/doc/src/sgml/ref/create_role.sgml
+++ b/doc/src/sgml/ref/create_role.sgml
@@ -198,7 +198,10 @@ CREATE ROLE <replaceable class="PARAMETER">name</replaceable> [ [ WITH ] <replac
       <listitem>
        <para>
         If role can log in, this specifies how many concurrent connections
-        the role can make.  -1 (the default) means no limit.
+        the role can make.  -1 (the default) means no limit. Note that only
+        normal connections are counted towards this limit. Neither prepared
+        transactions nor background worker connections are counted towards
+        this limit.
        </para>
       </listitem>
      </varlistentry>
diff --git a/src/backend/access/transam/twophase.c b/src/backend/access/transam/twophase.c
index 5b72c1dcf57..6fde2bd8bfd 100644
--- a/src/backend/access/transam/twophase.c
+++ b/src/backend/access/transam/twophase.c
@@ -420,6 +420,7 @@ MarkAsPreparing(TransactionId xid, const char *gid,
 	proc->backendId = InvalidBackendId;
 	proc->databaseId = databaseid;
 	proc->roleId = owner;
+	proc->isBackgroundWorker = false;
 	proc->lwWaiting = false;
 	proc->lwWaitMode = 0;
 	proc->waitLock = NULL;
diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
index 3f47b984eef..cd14667c16c 100644
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -2745,6 +2745,38 @@ CountDBBackends(Oid databaseid)
 }
 
 /*
+ * CountDBConnections --- counts database backends ignoring any background
+ *		worker processes
+ */
+int
+CountDBConnections(Oid databaseid)
+{
+	ProcArrayStruct *arrayP = procArray;
+	int			count = 0;
+	int			index;
+
+	LWLockAcquire(ProcArrayLock, LW_SHARED);
+
+	for (index = 0; index < arrayP->numProcs; index++)
+	{
+		int			pgprocno = arrayP->pgprocnos[index];
+		volatile PGPROC *proc = &allProcs[pgprocno];
+
+		if (proc->pid == 0)
+			continue;			/* do not count prepared xacts */
+		if (proc->isBackgroundWorker)
+			continue;			/* do not count background workers */
+		if (!OidIsValid(databaseid) ||
+			proc->databaseId == databaseid)
+			count++;
+	}
+
+	LWLockRelease(ProcArrayLock);
+
+	return count;
+}
+
+/*
  * CancelDBBackends --- cancel backends that are using specified database
  */
 void
@@ -2803,6 +2835,8 @@ CountUserBackends(Oid roleid)
 
 		if (proc->pid == 0)
 			continue;			/* do not count prepared xacts */
+		if (proc->isBackgroundWorker)
+			continue;			/* do not count background workers */
 		if (proc->roleId == roleid)
 			count++;
 	}
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 1b836f7c0ac..8f467bef504 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -370,6 +370,7 @@ InitProcess(void)
 	MyProc->backendId = InvalidBackendId;
 	MyProc->databaseId = InvalidOid;
 	MyProc->roleId = InvalidOid;
+	MyProc->isBackgroundWorker = IsBackgroundWorker;
 	MyPgXact->delayChkpt = false;
 	MyPgXact->vacuumFlags = 0;
 	/* NB -- autovac launcher intentionally does not set IS_AUTOVACUUM */
@@ -542,6 +543,7 @@ InitAuxiliaryProcess(void)
 	MyProc->backendId = InvalidBackendId;
 	MyProc->databaseId = InvalidOid;
 	MyProc->roleId = InvalidOid;
+	MyProc->isBackgroundWorker = IsBackgroundWorker;
 	MyPgXact->delayChkpt = false;
 	MyPgXact->vacuumFlags = 0;
 	MyProc->lwWaiting = false;
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index 21fdc6df6b1..4d0a2a7bed3 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -350,7 +350,7 @@ CheckMyDatabase(const char *name, bool am_superuser)
 		 */
 		if (dbform->datconnlimit >= 0 &&
 			!am_superuser &&
-			CountDBBackends(MyDatabaseId) > dbform->datconnlimit)
+			CountDBConnections(MyDatabaseId) > dbform->datconnlimit)
 			ereport(FATAL,
 					(errcode(ERRCODE_TOO_MANY_CONNECTIONS),
 					 errmsg("too many connections for database \"%s\"",
diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h
index 398fa8afdee..5f38fa6b4f1 100644
--- a/src/include/storage/proc.h
+++ b/src/include/storage/proc.h
@@ -103,6 +103,8 @@ struct PGPROC
 	Oid			databaseId;		/* OID of database this backend is using */
 	Oid			roleId;			/* OID of role using this backend */
 
+	bool		isBackgroundWorker; /* true if background worker. */
+
 	/*
 	 * While in hot standby mode, shows that a conflict signal has been sent
 	 * for the current transaction. Set/cleared while holding ProcArrayLock,
diff --git a/src/include/storage/procarray.h b/src/include/storage/procarray.h
index 0d5027fa64f..9d5a13eb3b2 100644
--- a/src/include/storage/procarray.h
+++ b/src/include/storage/procarray.h
@@ -73,6 +73,7 @@ extern pid_t CancelVirtualTransaction(VirtualTransactionId vxid, ProcSignalReaso
 
 extern bool MinimumActiveBackends(int min);
 extern int	CountDBBackends(Oid databaseid);
+extern int	CountDBConnections(Oid databaseid);
 extern void CancelDBBackends(Oid databaseid, ProcSignalReason sigmode, bool conflictPending);
 extern int	CountUserBackends(Oid roleid);
 extern bool CountOtherDBBackends(Oid databaseId,