diff --git a/src/db.c b/src/db.c
index 9daa5ddb..fea2f12e 100644
--- a/src/db.c
+++ b/src/db.c
@@ -616,3 +616,76 @@ void persistCommand(redisClient *c) {
         }
     }
 }
+
+/* -----------------------------------------------------------------------------
+ * API to get key arguments from commands
+ * ---------------------------------------------------------------------------*/
+
+int *getKeysUsingCommandTable(struct redisCommand *cmd,robj **argv, int argc, int *numkeys) {
+    int j, i = 0, last, *keys;
+    REDIS_NOTUSED(argv);
+
+    if (cmd->firstkey == 0) {
+        *numkeys = 0;
+        return NULL;
+    }
+    last = cmd->lastkey;
+    if (last < 0) last = argc+last;
+    keys = zmalloc(sizeof(int)*((last - cmd->firstkey)+1));
+    for (j = cmd->firstkey; j <= last; j += cmd->keystep) {
+        redisAssert(j < argc);
+        keys[i++] = j;
+    }
+    *numkeys = i;
+    return keys;
+}
+
+int *getKeysFromCommand(struct redisCommand *cmd,robj **argv, int argc, int *numkeys, int flags) {
+    if (cmd->getkeys_proc) {
+        return cmd->getkeys_proc(cmd,argv,argc,numkeys,flags);
+    } else {
+        return getKeysUsingCommandTable(cmd,argv,argc,numkeys);
+    }
+}
+
+void getKeysFreeResult(int *result) {
+    zfree(result);
+}
+
+int *noPreloadGetKeys(struct redisCommand *cmd,robj **argv, int argc, int *numkeys, int flags) {
+    if (flags & REDIS_GETKEYS_PRELOAD) {
+        *numkeys = 0;
+        return NULL;
+    } else {
+        return getKeysUsingCommandTable(cmd,argv,argc,numkeys);
+    }
+}
+
+int *renameGetKeys(struct redisCommand *cmd,robj **argv, int argc, int *numkeys, int flags) {
+    if (flags & REDIS_GETKEYS_PRELOAD) {
+        int *keys = zmalloc(sizeof(int));
+        *numkeys = 1;
+        keys[0] = 1;
+        return keys;
+    } else {
+        return getKeysUsingCommandTable(cmd,argv,argc,numkeys);
+    }
+}
+
+int *zunionInterGetKeys(struct redisCommand *cmd,robj **argv, int argc, int *numkeys, int flags) {
+    int i, num, *keys;
+    REDIS_NOTUSED(cmd);
+    REDIS_NOTUSED(flags);
+
+    num = atoi(argv[2]->ptr);
+    /* Sanity check. Don't return any key if the command is going to
+     * reply with syntax error. */
+    if (num > (argc-3)) {
+        *numkeys = 0;
+        return NULL;
+    }
+    keys = zmalloc(sizeof(int)*num);
+    for (i = 0; i < num; i++) keys[i] = 3+i;
+    *numkeys = num;
+    return keys;
+}
diff --git a/src/dscache.c b/src/dscache.c
index cbe9bb01..46300e63 100644
--- a/src/dscache.c
+++ b/src/dscache.c
@@ -903,59 +903,6 @@ int waitForSwappedKey(redisClient *c, robj *key) {
     return 1;
 }
 
-/* Preload keys for any command with first, last and step values for
- * the command keys prototype, as defined in the command table. */
-void waitForMultipleSwappedKeys(redisClient *c, struct redisCommand *cmd, int argc, robj **argv) {
-    int j, last;
-    if (cmd->vm_firstkey == 0) return;
-    last = cmd->vm_lastkey;
-    if (last < 0) last = argc+last;
-    for (j = cmd->vm_firstkey; j <= last; j += cmd->vm_keystep) {
-        redisAssert(j < argc);
-        waitForSwappedKey(c,argv[j]);
-    }
-}
-
-/* Preload keys needed for the ZUNIONSTORE and ZINTERSTORE commands.
- * Note that the number of keys to preload is user-defined, so we need to
- * apply a sanity check against argc. */
-void zunionInterBlockClientOnSwappedKeys(redisClient *c, struct redisCommand *cmd, int argc, robj **argv) {
-    int i, num;
-    REDIS_NOTUSED(cmd);
-
-    num = atoi(argv[2]->ptr);
-    if (num > (argc-3)) return;
-    for (i = 0; i < num; i++) {
-        waitForSwappedKey(c,argv[3+i]);
-    }
-}
-
-/* Preload keys needed to execute the entire MULTI/EXEC block.
- *
- * This function is called by blockClientOnSwappedKeys when EXEC is issued,
- * and will block the client when any command requires a swapped out value. */
-void execBlockClientOnSwappedKeys(redisClient *c, struct redisCommand *cmd, int argc, robj **argv) {
-    int i, margc;
-    struct redisCommand *mcmd;
-    robj **margv;
-    REDIS_NOTUSED(cmd);
-    REDIS_NOTUSED(argc);
-    REDIS_NOTUSED(argv);
-
-    if (!(c->flags & REDIS_MULTI)) return;
-    for (i = 0; i < c->mstate.count; i++) {
-        mcmd = c->mstate.commands[i].cmd;
-        margc = c->mstate.commands[i].argc;
-        margv = c->mstate.commands[i].argv;
-
-        if (mcmd->vm_preload_proc != NULL) {
-            mcmd->vm_preload_proc(c,mcmd,margc,margv);
-        } else {
-            waitForMultipleSwappedKeys(c,mcmd,margc,margv);
-        }
-    }
-}
-
 /* Is this client attempting to run a command against swapped keys?
  * If so, block it ASAP, load the keys in background, then resume it.
  *
@@ -967,10 +914,39 @@ void execBlockClientOnSwappedKeys(redisClient *c, struct redisCommand *cmd, int
  * Return 1 if the client is marked as blocked, 0 if the client can
  * continue as the keys it is going to access appear to be in memory. */
 int blockClientOnSwappedKeys(redisClient *c, struct redisCommand *cmd) {
-    if (cmd->vm_preload_proc != NULL) {
-        cmd->vm_preload_proc(c,cmd,c->argc,c->argv);
+    int *keyindex, numkeys, j, i;
+
+    /* EXEC is a special case, we need to preload all the commands
+     * queued into the transaction */
+    if (cmd->proc == execCommand) {
+        struct redisCommand *mcmd;
+        robj **margv;
+        int margc;
+
+        if (!(c->flags & REDIS_MULTI)) return 0;
+        for (i = 0; i < c->mstate.count; i++) {
+            mcmd = c->mstate.commands[i].cmd;
+            margc = c->mstate.commands[i].argc;
+            margv = c->mstate.commands[i].argv;
+
+            keyindex = getKeysFromCommand(mcmd,margv,margc,&numkeys,
+                                          REDIS_GETKEYS_PRELOAD);
+            for (j = 0; j < numkeys; j++) {
+                redisLog(REDIS_DEBUG,"Preloading %s",
+                    (char*)margv[keyindex[j]]->ptr);
+                waitForSwappedKey(c,margv[keyindex[j]]);
+            }
+            getKeysFreeResult(keyindex);
+        }
     } else {
-        waitForMultipleSwappedKeys(c,cmd,c->argc,c->argv);
+        keyindex = getKeysFromCommand(cmd,c->argv,c->argc,&numkeys,
+                                      REDIS_GETKEYS_PRELOAD);
+        for (j = 0; j < numkeys; j++) {
+            redisLog(REDIS_DEBUG,"Preloading %s",
+                (char*)c->argv[keyindex[j]]->ptr);
+            waitForSwappedKey(c,c->argv[keyindex[j]]);
+        }
+        getKeysFreeResult(keyindex);
     }
 
     /* If the client was blocked for at least one key, mark it as blocked. */
diff --git a/src/redis.c b/src/redis.c
index 866ac360..19fd912c 100644
--- a/src/redis.c
+++ b/src/redis.c
@@ -70,12 +70,12 @@ struct redisServer server; /* server global state */
 struct redisCommand *commandTable;
 struct redisCommand redisCommandTable[] = {
     {"get",getCommand,2,0,NULL,1,1,1,0,0},
-    {"set",setCommand,3,REDIS_CMD_DENYOOM,NULL,0,0,0,0,0},
-    {"setnx",setnxCommand,3,REDIS_CMD_DENYOOM,NULL,0,0,0,0,0},
-    {"setex",setexCommand,4,REDIS_CMD_DENYOOM,NULL,0,0,0,0,0},
+    {"set",setCommand,3,REDIS_CMD_DENYOOM,noPreloadGetKeys,1,1,1,0,0},
+    {"setnx",setnxCommand,3,REDIS_CMD_DENYOOM,noPreloadGetKeys,1,1,1,0,0},
+    {"setex",setexCommand,4,REDIS_CMD_DENYOOM,noPreloadGetKeys,2,2,1,0,0},
     {"append",appendCommand,3,REDIS_CMD_DENYOOM,NULL,1,1,1,0,0},
     {"strlen",strlenCommand,2,0,NULL,1,1,1,0,0},
-    {"del",delCommand,-2,0,NULL,0,0,0,0,0},
+    {"del",delCommand,-2,0,noPreloadGetKeys,1,-1,1,0,0},
     {"exists",existsCommand,2,0,NULL,1,1,1,0,0},
     {"setbit",setbitCommand,4,REDIS_CMD_DENYOOM,NULL,1,1,1,0,0},
     {"getbit",getbitCommand,3,0,NULL,1,1,1,0,0},
@@ -94,7 +94,7 @@ struct redisCommand redisCommandTable[] = {
     {"lpop",lpopCommand,2,0,NULL,1,1,1,0,0},
     {"brpop",brpopCommand,-3,0,NULL,1,1,1,0,0},
     {"brpoplpush",brpoplpushCommand,4,REDIS_CMD_DENYOOM,NULL,1,2,1,0,0},
-    {"blpop",blpopCommand,-3,0,NULL,1,1,1,0,0},
+    {"blpop",blpopCommand,-3,0,NULL,1,-2,1,0,0},
     {"llen",llenCommand,2,0,NULL,1,1,1,0,0},
     {"lindex",lindexCommand,3,0,NULL,1,1,1,0,0},
     {"lset",lsetCommand,4,REDIS_CMD_DENYOOM,NULL,1,1,1,0,0},
@@ -121,8 +121,8 @@ struct redisCommand redisCommandTable[] = {
     {"zrem",zremCommand,3,0,NULL,1,1,1,0,0},
     {"zremrangebyscore",zremrangebyscoreCommand,4,0,NULL,1,1,1,0,0},
     {"zremrangebyrank",zremrangebyrankCommand,4,0,NULL,1,1,1,0,0},
-    {"zunionstore",zunionstoreCommand,-4,REDIS_CMD_DENYOOM,zunionInterBlockClientOnSwappedKeys,0,0,0,0,0},
-    {"zinterstore",zinterstoreCommand,-4,REDIS_CMD_DENYOOM,zunionInterBlockClientOnSwappedKeys,0,0,0,0,0},
+    {"zunionstore",zunionstoreCommand,-4,REDIS_CMD_DENYOOM,zunionInterGetKeys,0,0,0,0,0},
+    {"zinterstore",zinterstoreCommand,-4,REDIS_CMD_DENYOOM,zunionInterGetKeys,0,0,0,0,0},
     {"zrange",zrangeCommand,-4,0,NULL,1,1,1,0,0},
     {"zrangebyscore",zrangebyscoreCommand,-4,0,NULL,1,1,1,0,0},
     {"zrevrangebyscore",zrevrangebyscoreCommand,-4,0,NULL,1,1,1,0,0},
@@ -152,10 +152,10 @@ struct redisCommand redisCommandTable[] = {
     {"randomkey",randomkeyCommand,1,0,NULL,0,0,0,0,0},
     {"select",selectCommand,2,0,NULL,0,0,0,0,0},
     {"move",moveCommand,3,0,NULL,1,1,1,0,0},
-    {"rename",renameCommand,3,0,NULL,1,1,1,0,0},
-    {"renamenx",renamenxCommand,3,0,NULL,1,1,1,0,0},
-    {"expire",expireCommand,3,0,NULL,0,0,0,0,0},
-    {"expireat",expireatCommand,3,0,NULL,0,0,0,0,0},
+    {"rename",renameCommand,3,0,renameGetKeys,1,2,1,0,0},
+    {"renamenx",renamenxCommand,3,0,renameGetKeys,1,2,1,0,0},
+    {"expire",expireCommand,3,0,NULL,1,1,1,0,0},
+    {"expireat",expireatCommand,3,0,NULL,1,1,1,0,0},
     {"keys",keysCommand,2,0,NULL,0,0,0,0,0},
     {"dbsize",dbsizeCommand,1,0,NULL,0,0,0,0,0},
     {"auth",authCommand,2,0,NULL,0,0,0,0,0},
@@ -168,7 +168,7 @@ struct redisCommand redisCommandTable[] = {
     {"lastsave",lastsaveCommand,1,0,NULL,0,0,0,0,0},
     {"type",typeCommand,2,0,NULL,1,1,1,0,0},
     {"multi",multiCommand,1,0,NULL,0,0,0,0,0},
-    {"exec",execCommand,1,REDIS_CMD_DENYOOM,execBlockClientOnSwappedKeys,0,0,0,0,0},
+    {"exec",execCommand,1,REDIS_CMD_DENYOOM,NULL,0,0,0,0,0},
     {"discard",discardCommand,1,0,NULL,0,0,0,0,0},
     {"sync",syncCommand,1,0,NULL,0,0,0,0,0},
     {"flushdb",flushdbCommand,1,0,NULL,0,0,0,0,0},
@@ -186,7 +186,7 @@ struct redisCommand redisCommandTable[] = {
     {"psubscribe",psubscribeCommand,-2,0,NULL,0,0,0,0,0},
     {"punsubscribe",punsubscribeCommand,-1,0,NULL,0,0,0,0,0},
     {"publish",publishCommand,3,REDIS_CMD_FORCE_REPLICATION,NULL,0,0,0,0,0},
-    {"watch",watchCommand,-2,0,NULL,0,0,0,0,0},
+    {"watch",watchCommand,-2,0,noPreloadGetKeys,1,-1,1,0,0},
     {"unwatch",unwatchCommand,1,0,NULL,0,0,0,0,0}
 };
 
diff --git a/src/redis.h b/src/redis.h
index cdddb601..b5188330 100644
--- a/src/redis.h
+++ b/src/redis.h
@@ -507,20 +507,19 @@ typedef struct pubsubPattern {
 } pubsubPattern;
 
 typedef void redisCommandProc(redisClient *c);
-typedef void redisVmPreloadProc(redisClient *c, struct redisCommand *cmd, int argc, robj **argv);
+typedef int *redisGetKeysProc(struct redisCommand *cmd, robj **argv, int argc, int *numkeys, int flags);
 struct redisCommand {
     char *name;
     redisCommandProc *proc;
     int arity;
     int flags;
-    /* Use a function to determine which keys need to be loaded
-     * in the background prior to executing this command. Takes precedence
-     * over vm_firstkey and others, ignored when NULL */
-    redisVmPreloadProc *vm_preload_proc;
+    /* Use a function to determine keys arguments in a command line.
+     * Used both for diskstore preloading and Redis Cluster. */
+    redisGetKeysProc *getkeys_proc;
     /* What keys should be loaded in background when calling this command? */
-    int vm_firstkey; /* The first argument that's a key (0 = no keys) */
-    int vm_lastkey;  /* THe last argument that's a key */
-    int vm_keystep;  /* The step between first and last key */
+    int firstkey; /* The first argument that's a key (0 = no keys) */
+    int lastkey;  /* THe last argument that's a key */
+    int keystep;  /* The step between first and last key */
     long long microseconds, calls;
 };
 
@@ -829,8 +828,6 @@ void freeIOJob(iojob *j);
 void queueIOJob(iojob *j);
 void waitEmptyIOJobsQueue(void);
 void processAllPendingIOJobs(void);
-void zunionInterBlockClientOnSwappedKeys(redisClient *c, struct redisCommand *cmd, int argc, robj **argv);
-void execBlockClientOnSwappedKeys(redisClient *c, struct redisCommand *cmd, int argc, robj **argv);
 int blockClientOnSwappedKeys(redisClient *c, struct redisCommand *cmd);
 int dontWaitForSwappedKey(redisClient *c, robj *key);
 void handleClientsBlockedOnSwappedKey(redisDb *db, robj *key);
@@ -917,6 +914,15 @@ int selectDb(redisClient *c, int id);
 void signalModifiedKey(redisDb *db, robj *key);
 void signalFlushedDb(int dbid);
 
+/* API to get key arguments from commands */
+#define REDIS_GETKEYS_ALL 0
+#define REDIS_GETKEYS_PRELOAD 1
+int *getKeysFromCommand(struct redisCommand *cmd, robj **argv, int argc, int *numkeys, int flags);
+void getKeysFreeResult(int *result);
+int *noPreloadGetKeys(struct redisCommand *cmd,robj **argv, int argc, int *numkeys, int flags);
+int *renameGetKeys(struct redisCommand *cmd,robj **argv, int argc, int *numkeys, int flags);
+int *zunionInterGetKeys(struct redisCommand *cmd,robj **argv, int argc, int *numkeys, int flags);
+
 /* Git SHA1 */
 char *redisGitSHA1(void);
 char *redisGitDirty(void);