diff -p -up postfix-2.7.0/src/postmap/postmap.c.dbupgrade postfix-2.7.0/src/postmap/postmap.c
--- postfix-2.7.0/src/postmap/postmap.c.dbupgrade	2009-04-17 20:04:00.000000000 +0000
+++ postfix-2.7.0/src/postmap/postmap.c	2010-02-20 11:10:32.040323376 +0000
@@ -5,7 +5,7 @@
 /*	Postfix lookup table management
 /* SYNOPSIS
 /* .fi
-/*	\fBpostmap\fR [\fB-Nbfhimnoprsvw\fR] [\fB-c \fIconfig_dir\fR]
+/*	\fBpostmap\fR [\fB-Nbfhimnoprsuvw\fR] [\fB-c \fIconfig_dir\fR]
 /*	[\fB-d \fIkey\fR] [\fB-q \fIkey\fR]
 /*		[\fIfile_type\fR:]\fIfile_name\fR ...
 /* DESCRIPTION
@@ -151,6 +151,8 @@
 /* .sp
 /*	This feature is available in Postfix version 2.2 and later,
 /*	and is not available for all database types.
+/* .IP \fB-u\fR
+/*	Upgrade the database to the current version.
 /* .IP \fB-v\fR
 /*	Enable verbose logging for debugging purposes. Multiple \fB-v\fR
 /*	options make the software increasingly verbose.
@@ -723,11 +725,23 @@ static void postmap_seq(const char *map_
     dict_close(dict);
 }
 
+/* postmap_upgrade - upgrade a map */
+
+static int postmap_upgrade(const char *map_type, const char *map_name)
+{
+    DICT   *dict;
+
+    dict = dict_open3(map_type, map_name, O_RDWR,
+			DICT_FLAG_LOCK|DICT_FLAG_UPGRADE);
+    dict_close(dict);
+    return (dict != 0);
+}
+
 /* usage - explain */
 
 static NORETURN usage(char *myname)
 {
-    msg_fatal("usage: %s [-Nfinoprsvw] [-c config_dir] [-d key] [-q key] [map_type:]file...",
+    msg_fatal("usage: %s [-Nfhimnoprsuvw] [-c config_dir] [-d key] [-q key] [map_type:]file...",
 	      myname);
 }
 
@@ -743,6 +757,7 @@ int     main(int argc, char **argv)
     int     postmap_flags = POSTMAP_FLAG_AS_OWNER | POSTMAP_FLAG_SAVE_PERM;
     int     open_flags = O_RDWR | O_CREAT | O_TRUNC;
     int     dict_flags = DICT_FLAG_DUP_WARN | DICT_FLAG_FOLD_FIX;
+    int     upgrade = 0;
     char   *query = 0;
     char   *delkey = 0;
     int     sequence = 0;
@@ -787,7 +802,7 @@ int     main(int argc, char **argv)
     /*
      * Parse JCL.
      */
-    while ((ch = GETOPT(argc, argv, "Nbc:d:fhimnopq:rsvw")) > 0) {
+    while ((ch = GETOPT(argc, argv, "Nbc:d:fhimnopq:rsuvw")) > 0) {
 	switch (ch) {
 	default:
 	    usage(argv[0]);
@@ -804,8 +819,8 @@ int     main(int argc, char **argv)
 		msg_fatal("out of memory");
 	    break;
 	case 'd':
-	    if (sequence || query || delkey)
-		msg_fatal("specify only one of -s -q or -d");
+	    if (sequence || query || delkey || upgrade)
+		msg_fatal("specify only one of -s -q -u or -d");
 	    delkey = optarg;
 	    break;
 	case 'f':
@@ -831,8 +846,8 @@ int     main(int argc, char **argv)
 	    postmap_flags &= ~POSTMAP_FLAG_SAVE_PERM;
 	    break;
 	case 'q':
-	    if (sequence || query || delkey)
-		msg_fatal("specify only one of -s -q or -d");
+	    if (sequence || query || delkey || upgrade)
+		msg_fatal("specify only one of -s -q -u or -d");
 	    query = optarg;
 	    break;
 	case 'r':
@@ -840,10 +855,15 @@ int     main(int argc, char **argv)
 	    dict_flags |= DICT_FLAG_DUP_REPLACE;
 	    break;
 	case 's':
-	    if (query || delkey)
-		msg_fatal("specify only one of -s or -q or -d");
+	    if (query || delkey || upgrade)
+		msg_fatal("specify only one of -s or -q -u or -d");
 	    sequence = 1;
 	    break;
+	case 'u':
+	    if (sequence || query || delkey || upgrade)
+		msg_fatal("specify only one of -s -q -u or -d");
+	    upgrade=1;
+	    break;
 	case 'v':
 	    msg_verbose++;
 	    break;
@@ -914,6 +934,21 @@ int     main(int argc, char **argv)
 	    exit(0);
 	}
 	exit(1);
+    } else if (upgrade) {			/* Upgrade the map(s) */
+	int success = 1;
+	if (optind + 1 > argc)
+	    usage(argv[0]);
+	while (optind < argc) {
+	    if ((path_name = split_at(argv[optind], ':')) != 0) {
+		success &= postmap_upgrade(argv[optind], path_name);
+	    } else {
+		success &= postmap_upgrade(var_db_type, argv[optind]);
+	    }
+	    if (!success)
+		exit(1);
+	    optind++;
+	}
+	exit(0);
     } else {					/* create/update map(s) */
 	if (optind + 1 > argc)
 	    usage(argv[0]);
diff -p -up postfix-2.7.0/src/util/dict.h.dbupgrade postfix-2.7.0/src/util/dict.h
--- postfix-2.7.0/src/util/dict.h.dbupgrade	2007-12-03 19:42:26.000000000 +0000
+++ postfix-2.7.0/src/util/dict.h	2010-02-20 11:10:32.040323376 +0000
@@ -66,6 +66,7 @@ extern DICT *dict_debug(DICT *);
 #define DICT_FLAG_NO_UNAUTH	(1<<13)	/* disallow unauthenticated data */
 #define DICT_FLAG_FOLD_FIX	(1<<14)	/* case-fold key with fixed-case map */
 #define DICT_FLAG_FOLD_MUL	(1<<15)	/* case-fold key with multi-case map */
+#define DICT_FLAG_UPGRADE	(1<<30) /* Upgrade the db */
 #define DICT_FLAG_FOLD_ANY	(DICT_FLAG_FOLD_FIX | DICT_FLAG_FOLD_MUL)
 
  /* IMPORTANT: Update the dict_mask[] table when the above changes */
diff -p -up postfix-2.7.0/src/util/dict_db.c.dbupgrade postfix-2.7.0/src/util/dict_db.c
--- postfix-2.7.0/src/util/dict_db.c.dbupgrade	2010-01-02 22:28:08.000000000 +0100
+++ postfix-2.7.0/src/util/dict_db.c	2010-02-20 15:51:14.850299909 +0100
@@ -675,6 +675,12 @@ static DICT *dict_db_open(const char *cl
 	msg_fatal("set DB cache size %d: %m", dict_db_cache_size);
     if (type == DB_HASH && db->set_h_nelem(db, DICT_DB_NELM) != 0)
 	msg_fatal("set DB hash element count %d: %m", DICT_DB_NELM);
+    if (dict_flags & DICT_FLAG_UPGRADE) {
+	if (msg_verbose)
+	    msg_info("upgrading database %s",db_path);
+	if ((errno = db->upgrade(db,db_path,0)) != 0)
+	    msg_fatal("upgrade of database %s: %m",db_path);
+    }
 #if (DB_VERSION_MAJOR == 4 && DB_VERSION_MINOR > 0)
     if ((errno = db->open(db, 0, db_path, 0, type, db_flags, 0644)) != 0)
 	msg_fatal("open database %s: %m", db_path);
diff -p -up postfix-2.7.0/src/util/dict_dbm.c.dbupgrade postfix-2.7.0/src/util/dict_dbm.c
--- postfix-2.7.0/src/util/dict_dbm.c.dbupgrade	2009-12-24 23:53:04.000000000 +0100
+++ postfix-2.7.0/src/util/dict_dbm.c	2010-02-20 15:51:14.850299909 +0100
@@ -409,6 +409,10 @@ DICT   *dict_dbm_open(const char *path, 
     char   *dbm_path;
     int     lock_fd;
 
+#ifdef HAVE_GDBM
+    msg_fatal("%s: gdbm maps use locking that is incompatible with postfix.  Use a hash map instead.",
+		 path);
+#endif
     /*
      * Note: DICT_FLAG_LOCK is used only by programs that do fine-grained (in
      * the time domain) locking while accessing individual database records.