9 files changed, 50 insertions, 14 deletions
diff --git a/src/backend/access/transam/twophase.c b/src/backend/access/transam/twophase.c
index f85c2c6842..636216f40a 100644
--- a/src/backend/access/transam/twophase.c
+++ b/src/backend/access/transam/twophase.c
@@ -280,6 +280,7 @@ MarkAsPreparing(TransactionId xid, const char *gid,
 	gxact->proc.databaseId = databaseid;
 	gxact->proc.roleId = owner;
 	gxact->proc.inVacuum = false;
+	gxact->proc.isAutovacuum = false;
 	gxact->proc.lwWaiting = false;
 	gxact->proc.lwExclusive = false;
 	gxact->proc.lwWaitLink = NULL;
diff --git a/src/backend/commands/dbcommands.c b/src/backend/commands/dbcommands.c
index a19695bab1..eb025ee6de 100644
--- a/src/backend/commands/dbcommands.c
+++ b/src/backend/commands/dbcommands.c
@@ -250,11 +250,11 @@ createdb(const CreatedbStmt *stmt)
 	 * (exception is to allow CREATE DB while connected to template1).
 	 * Otherwise we might copy inconsistent data.
 	 */
-	if (DatabaseHasActiveBackends(src_dboid, true))
+	if (DatabaseCancelAutovacuumActivity(src_dboid, true))
 		ereport(ERROR,
 				(errcode(ERRCODE_OBJECT_IN_USE),
-			errmsg("source database \"%s\" is being accessed by other users",
-				   dbtemplate)));
+				 errmsg("source database \"%s\" is being accessed by other users",
+						dbtemplate)));
 
 	/* If encoding is defaulted, use source's encoding */
 	if (encoding < 0)
@@ -602,7 +602,7 @@ dropdb(const char *dbname, bool missing_ok)
 	 * Check for active backends in the target database.  (Because we hold the
 	 * database lock, no new ones can start after this.)
 	 */
-	if (DatabaseHasActiveBackends(db_id, false))
+	if (DatabaseCancelAutovacuumActivity(db_id, false))
 		ereport(ERROR,
 				(errcode(ERRCODE_OBJECT_IN_USE),
 				 errmsg("database \"%s\" is being accessed by other users",
@@ -706,7 +706,7 @@ RenameDatabase(const char *oldname, const char *newname)
 	 * Make sure the database does not have active sessions.  This is the same
 	 * concern as above, but applied to other sessions.
 	 */
-	if (DatabaseHasActiveBackends(db_id, false))
+	if (DatabaseCancelAutovacuumActivity(db_id, false))
 		ereport(ERROR,
 				(errcode(ERRCODE_OBJECT_IN_USE),
 				 errmsg("database \"%s\" is being accessed by other users",
diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index 68455e066c..42cfcfb6ec 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -216,6 +216,15 @@ autovac_forkexec(void)
 
 	return postmaster_forkexec(ac, av);
 }
+
+/*
+ * We need this set from the outside, before InitProcess is called
+ */
+void
+AutovacuumIAm(void)
+{
+	am_autovacuum = true;
+}
 #endif   /* EXEC_BACKEND */
 
 /*
@@ -307,8 +316,8 @@ AutoVacMain(int argc, char *argv[])
 		EmitErrorReport();
 
 		/*
-		 * We can now go away.	Note that because we'll call InitProcess, a
-		 * callback will be registered to do ProcKill, which will clean up
+		 * We can now go away.	Note that because we called InitProcess, a
+		 * callback was registered to do ProcKill, which will clean up
 		 * necessary state.
 		 */
 		proc_exit(0);
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index f5675231b6..36339ad999 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -3298,6 +3298,10 @@ SubPostmasterMain(int argc, char *argv[])
 		strcmp(argv[1], "--forkboot") == 0)
 		PGSharedMemoryReAttach();
 
+	/* autovacuum needs this set before calling InitProcess */
+	if (strcmp(argv[1], "--forkautovac") == 0)
+		AutovacuumIAm();
+
 	/*
 	 * Start our win32 signal implementation. This has to be done after we
 	 * read the backend variables, because we need to pick up the signal pipe
diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
index 79a41029cf..2d1493bb09 100644
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -29,6 +29,8 @@
  */
 #include "postgres.h"
 
+#include <signal.h>
+
 #include "access/subtrans.h"
 #include "access/transam.h"
 #include "access/xact.h"
@@ -678,7 +680,9 @@ GetSnapshotData(Snapshot snapshot, bool serializable)
 }
 
 /*
- * DatabaseHasActiveBackends -- are there any backends running in the given DB
+ * DatabaseCancelAutovacuumActivity -- are there any backends running in the
+ * given DB, apart from autovacuum?  If an autovacuum process is running on the
+ * database, kill it and restart the counting.
  *
  * If 'ignoreMyself' is TRUE, ignore this particular backend while checking
  * for backends in the target database.
@@ -691,11 +695,16 @@ GetSnapshotData(Snapshot snapshot, bool serializable)
  * backend startup.
  */
 bool
-DatabaseHasActiveBackends(Oid databaseId, bool ignoreMyself)
+DatabaseCancelAutovacuumActivity(Oid databaseId, bool ignoreMyself)
 {
-	bool		result = false;
 	ProcArrayStruct *arrayP = procArray;
 	int			index;
+	int			num;
+
+restart:
+	num = 0;
+
+	CHECK_FOR_INTERRUPTS();
 
 	LWLockAcquire(ProcArrayLock, LW_SHARED);
 
@@ -708,14 +717,22 @@ DatabaseHasActiveBackends(Oid databaseId, bool ignoreMyself)
 			if (ignoreMyself && proc == MyProc)
 				continue;
 
-			result = true;
-			break;
+			num++;
+
+			if (proc->isAutovacuum)
+			{
+				/* an autovacuum -- kill it and restart */
+				LWLockRelease(ProcArrayLock);
+				kill(proc->pid, SIGINT);
+				pg_usleep(100 * 1000);		/* 100ms */
+				goto restart;
+			}
 		}
 	}
 
 	LWLockRelease(ProcArrayLock);
 
-	return result;
+	return (num != 0);
 }
 
 /*
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 2cb629aa4a..8cb1e0340c 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -38,6 +38,7 @@
 #include "access/transam.h"
 #include "access/xact.h"
 #include "miscadmin.h"
+#include "postmaster/autovacuum.h"
 #include "storage/ipc.h"
 #include "storage/proc.h"
 #include "storage/procarray.h"
@@ -258,6 +259,7 @@ InitProcess(void)
 	MyProc->databaseId = InvalidOid;
 	MyProc->roleId = InvalidOid;
 	MyProc->inVacuum = false;
+	MyProc->isAutovacuum = IsAutoVacuumProcess();
 	MyProc->lwWaiting = false;
 	MyProc->lwExclusive = false;
 	MyProc->lwWaitLink = NULL;
@@ -390,6 +392,7 @@ InitDummyProcess(void)
 	MyProc->databaseId = InvalidOid;
 	MyProc->roleId = InvalidOid;
 	MyProc->inVacuum = false;
+	MyProc->isAutovacuum = false;
 	MyProc->lwWaiting = false;
 	MyProc->lwExclusive = false;
 	MyProc->lwWaitLink = NULL;
diff --git a/src/include/postmaster/autovacuum.h b/src/include/postmaster/autovacuum.h
index e83684441c..4c7671faa8 100644
--- a/src/include/postmaster/autovacuum.h
+++ b/src/include/postmaster/autovacuum.h
@@ -36,6 +36,7 @@ extern void autovac_stopped(void);
 
 #ifdef EXEC_BACKEND
 extern void AutoVacMain(int argc, char *argv[]);
+extern void AutovacuumIAm(void);
 #endif
 
 #endif   /* AUTOVACUUM_H */
diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h
index fed061bb29..0012c24133 100644
--- a/src/include/storage/proc.h
+++ b/src/include/storage/proc.h
@@ -75,6 +75,7 @@ struct PGPROC
 	Oid			roleId;			/* OID of role using this backend */
 
 	bool		inVacuum;		/* true if current xact is a LAZY VACUUM */
+	bool		isAutovacuum;	/* true if it's autovacuum */
 
 	/* Info about LWLock the process is currently waiting for, if any. */
 	bool		lwWaiting;		/* true if waiting for an LW lock */
diff --git a/src/include/storage/procarray.h b/src/include/storage/procarray.h
index 7fe9988e53..583235d746 100644
--- a/src/include/storage/procarray.h
+++ b/src/include/storage/procarray.h
@@ -29,7 +29,7 @@ extern TransactionId GetOldestXmin(bool allDbs, bool ignoreVacuum);
 extern PGPROC *BackendPidGetProc(int pid);
 extern int	BackendXidGetPid(TransactionId xid);
 extern bool IsBackendPid(int pid);
-extern bool DatabaseHasActiveBackends(Oid databaseId, bool ignoreMyself);
+extern bool DatabaseCancelAutovacuumActivity(Oid databaseId, bool ignoreMyself);
 
 extern int	CountActiveBackends(void);
 extern int	CountDBBackends(Oid databaseid);