Add new function BackgroundWorkerInitializeConnectionByOid.

Sometimes it's useful for a background worker to be able to initialize
its database connection by OID rather than by name, so provide a way
to do that.

1 files changed, 8 insertions, 5 deletions

diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index 1f5cf06f234..983b237d7a1 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -523,6 +523,9 @@ BaseInit(void)
  * name can be returned to the caller in out_dbname.  If out_dbname isn't
  * NULL, it must point to a buffer of size NAMEDATALEN.
  *
+ * Similarly, the username can be passed by name, using the username parameter,
+ * or by OID using the useroid parameter.
+ *
  * In bootstrap mode no parameters are used.  The autovacuum launcher process
  * doesn't use any parameters either, because it only goes far enough to be
  * able to read pg_database; it doesn't connect to any particular database.
@@ -537,7 +540,7 @@ BaseInit(void)
  */
 void
 InitPostgres(const char *in_dbname, Oid dboid, const char *username,
-			 char *out_dbname)
+			 Oid useroid, char *out_dbname)
 {
 	bool		bootstrap = IsBootstrapProcessingMode();
 	bool		am_superuser;
@@ -692,18 +695,18 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 					(errcode(ERRCODE_UNDEFINED_OBJECT),
 					 errmsg("no roles are defined in this database system"),
 					 errhint("You should immediately run CREATE USER \"%s\" SUPERUSER;.",
-							 username)));
+							 username != NULL ? username : "postgres")));
 	}
 	else if (IsBackgroundWorker)
 	{
-		if (username == NULL)
+		if (username == NULL && !OidIsValid(useroid))
 		{
 			InitializeSessionUserIdStandalone();
 			am_superuser = true;
 		}
 		else
 		{
-			InitializeSessionUserId(username);
+			InitializeSessionUserId(username, useroid);
 			am_superuser = superuser();
 		}
 	}
@@ -712,7 +715,7 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 		/* normal multiuser case */
 		Assert(MyProcPort != NULL);
 		PerformAuthentication(MyProcPort);
-		InitializeSessionUserId(username);
+		InitializeSessionUserId(username, useroid);
 		am_superuser = superuser();
 	}