diff --git a/src/db.c b/src/db.c
index 50576202..498d12b9 100644
--- a/src/db.c
+++ b/src/db.c
@@ -63,10 +63,7 @@ robj *lookupKey(redisDb *db, robj *key, int flags) {
         /* Update the access time for the ageing algorithm.
          * Don't do it if we have a saving child, as this will trigger
          * a copy on write madness. */
-        if (server.rdb_child_pid == -1 &&
-            server.aof_child_pid == -1 &&
-            !(flags & LOOKUP_NOTOUCH))
-        {
+        if (!hasActiveChildProcess() && !(flags & LOOKUP_NOTOUCH)){
             if (server.maxmemory_policy & MAXMEMORY_FLAG_LFU) {
                 updateLFU(val);
             } else {
@@ -86,6 +83,7 @@ robj *lookupKey(redisDb *db, robj *key, int flags) {
  * 1. A key gets expired if it reached it's TTL.
  * 2. The key last access time is updated.
  * 3. The global keys hits/misses stats are updated (reported in INFO).
+ * 4. If keyspace notifications are enabled, a "keymiss" notification is fired.
  *
  * This API should not be used when we write to the key after obtaining
  * the object linked to the key, but only for read only operations.
@@ -109,6 +107,7 @@ robj *lookupKeyReadWithFlags(redisDb *db, robj *key, int flags) {
          * to return NULL ASAP. */
         if (server.masterhost == NULL) {
             server.stat_keyspace_misses++;
+            notifyKeyspaceEvent(NOTIFY_KEY_MISS, "keymiss", key, db->id);
             return NULL;
         }
 
@@ -120,7 +119,7 @@ robj *lookupKeyReadWithFlags(redisDb *db, robj *key, int flags) {
          * However, if the command caller is not the master, and as additional
          * safety measure, the command invoked is a read-only command, we can
          * safely return NULL here, and provide a more consistent behavior
-         * to clients accessign expired values in a read-only fashion, that
+         * to clients accessing expired values in a read-only fashion, that
          * will say the key as non existing.
          *
          * Notably this covers GETs when slaves are used to scale reads. */
@@ -130,12 +129,15 @@ robj *lookupKeyReadWithFlags(redisDb *db, robj *key, int flags) {
             server.current_client->cmd->flags & CMD_READONLY)
         {
             server.stat_keyspace_misses++;
+            notifyKeyspaceEvent(NOTIFY_KEY_MISS, "keymiss", key, db->id);
             return NULL;
         }
     }
     val = lookupKey(db,key,flags);
-    if (val == NULL)
+    if (val == NULL) {
         server.stat_keyspace_misses++;
+        notifyKeyspaceEvent(NOTIFY_KEY_MISS, "keymiss", key, db->id);
+    }
     else
         server.stat_keyspace_hits++;
     return val;
@@ -152,9 +154,13 @@ robj *lookupKeyRead(redisDb *db, robj *key) {
  *
  * Returns the linked value object if the key exists or NULL if the key
  * does not exist in the specified DB. */
-robj *lookupKeyWrite(redisDb *db, robj *key) {
+robj *lookupKeyWriteWithFlags(redisDb *db, robj *key, int flags) {
     expireIfNeeded(db,key);
-    return lookupKey(db,key,LOOKUP_NONE);
+    return lookupKey(db,key,flags);
+}
+
+robj *lookupKeyWrite(redisDb *db, robj *key) {
+    return lookupKeyWriteWithFlags(db, key, LOOKUP_NONE);
 }
 
 robj *lookupKeyReadOrReply(client *c, robj *key, robj *reply) {
@@ -179,9 +185,28 @@ void dbAdd(redisDb *db, robj *key, robj *val) {
 
     serverAssertWithInfo(NULL,key,retval == DICT_OK);
     if (val->type == OBJ_LIST ||
-        val->type == OBJ_ZSET)
+        val->type == OBJ_ZSET ||
+        val->type == OBJ_STREAM)
         signalKeyAsReady(db, key);
+    if (server.cluster_enabled) slotToKeyAdd(key->ptr);
+}
+
+/* This is a special version of dbAdd() that is used only when loading
+ * keys from the RDB file: the key is passed as an SDS string that is
+ * retained by the function (and not freed by the caller).
+ *
+ * Moreover this function will not abort if the key is already busy, to
+ * give more control to the caller, nor will signal the key as ready
+ * since it is not useful in this context.
+ *
+ * The function returns 1 if the key was added to the database, taking
+ * ownership of the SDS string, otherwise 0 is returned, and is up to the
+ * caller to free the SDS string. */
+int dbAddRDBLoad(redisDb *db, sds key, robj *val) {
+    int retval = dictAdd(db->dict, key, val);
+    if (retval != DICT_OK) return 0;
     if (server.cluster_enabled) slotToKeyAdd(key);
+    return 1;
 }
 
 /* Overwrite an existing key with a new value. Incrementing the reference
@@ -213,20 +238,30 @@ void dbOverwrite(redisDb *db, robj *key, robj *val) {
  *
  * 1) The ref count of the value object is incremented.
  * 2) clients WATCHing for the destination key notified.
- * 3) The expire time of the key is reset (the key is made persistent).
+ * 3) The expire time of the key is reset (the key is made persistent),
+ *    unless 'keepttl' is true.
  *
- * All the new keys in the database should be created via this interface. */
-void setKey(redisDb *db, robj *key, robj *val) {
+ * All the new keys in the database should be created via this interface.
+ * The client 'c' argument may be set to NULL if the operation is performed
+ * in a context where there is no clear client performing the operation. */
+void genericSetKey(client *c, redisDb *db, robj *key, robj *val, int keepttl, int signal) {
     if (lookupKeyWrite(db,key) == NULL) {
         dbAdd(db,key,val);
     } else {
         dbOverwrite(db,key,val);
     }
     incrRefCount(val);
-    removeExpire(db,key);
-    signalModifiedKey(db,key);
+    if (!keepttl) removeExpire(db,key);
+    if (signal) signalModifiedKey(c,db,key);
 }
 
+/* Common case for genericSetKey() where the TTL is not retained. */
+void setKey(client *c, redisDb *db, robj *key, robj *val) {
+    genericSetKey(c,db,key,val,0,1);
+}
+
+/* Return true if the specified key exists in the specified database.
+ * LRU/LFU info is not updated in any way. */
 int dbExists(redisDb *db, robj *key) {
     return dictFind(db->dict,key->ptr) != NULL;
 }
@@ -244,7 +279,7 @@ robj *dbRandomKey(redisDb *db) {
         sds key;
         robj *keyobj;
 
-        de = dictGetRandomKey(db->dict);
+        de = dictGetFairRandomKey(db->dict);
         if (de == NULL) return NULL;
 
         key = dictGetKey(de);
@@ -276,7 +311,7 @@ int dbSyncDelete(redisDb *db, robj *key) {
      * the key, because it is shared with the main dictionary. */
     if (dictSize(db->expires) > 0) dictDelete(db->expires,key->ptr);
     if (dictDelete(db->dict,key->ptr) == DICT_OK) {
-        if (server.cluster_enabled) slotToKeyDel(key);
+        if (server.cluster_enabled) slotToKeyDel(key->ptr);
         return 1;
     } else {
         return 0;
@@ -336,14 +371,19 @@ robj *dbUnshareStringValue(redisDb *db, robj *key, robj *o) {
  * DB number if we want to flush only a single Redis database number.
  *
  * Flags are be EMPTYDB_NO_FLAGS if no special flags are specified or
- * EMPTYDB_ASYNC if we want the memory to be freed in a different thread
+ * 1. EMPTYDB_ASYNC if we want the memory to be freed in a different thread.
+ * 2. EMPTYDB_BACKUP if we want to empty the backup dictionaries created by
+ *    disklessLoadMakeBackups. In that case we only free memory and avoid
+ *    firing module events.
  * and the function to return ASAP.
  *
- * On success the fuction returns the number of keys removed from the
+ * On success the function returns the number of keys removed from the
  * database(s). Otherwise -1 is returned in the specific case the
  * DB number is out of range, and errno is set to EINVAL. */
-PORT_LONGLONG emptyDb(int dbnum, int flags, void(callback)(void*)) {
+PORT_LONGLONG emptyDb(redisDb *dbarray, int dbnum, int flags, void(callback)(void*)) {
     int async = (flags & EMPTYDB_ASYNC);
+    int backup = (flags & EMPTYDB_BACKUP); /* Just free the memory, nothing else */
+    RedisModuleFlushInfoV1 fi = {REDISMODULE_FLUSHINFO_VERSION,!async,dbnum};
     PORT_LONGLONG removed = 0;
 
     if (dbnum < -1 || dbnum >= server.dbnum) {
@@ -351,6 +391,19 @@ PORT_LONGLONG emptyDb(int dbnum, int flags, void(callback)(void*)) {
         return -1;
     }
 
+    /* Pre-flush actions */
+    if (!backup) {
+        /* Fire the flushdb modules event. */
+        moduleFireServerEvent(REDISMODULE_EVENT_FLUSHDB,
+                              REDISMODULE_SUBEVENT_FLUSHDB_START,
+                              &fi);
+
+        /* Make sure the WATCHed keys are affected by the FLUSH* commands.
+         * Note that we need to call the function while the keys are still
+         * there. */
+        signalFlushedDb(dbnum);
+    }
+
     int startdb, enddb;
     if (dbnum == -1) {
         startdb = 0;
@@ -360,25 +413,40 @@ PORT_LONGLONG emptyDb(int dbnum, int flags, void(callback)(void*)) {
     }
 
     for (int j = startdb; j <= enddb; j++) {
-        removed += dictSize(server.db[j].dict);
+        removed += dictSize(dbarray[j].dict);
         if (async) {
-            emptyDbAsync(&server.db[j]);
+            emptyDbAsync(&dbarray[j]);
         } else {
-            dictEmpty(server.db[j].dict,callback);
-            dictEmpty(server.db[j].expires,callback);
+            dictEmpty(dbarray[j].dict,callback);
+            dictEmpty(dbarray[j].expires,callback);
         }
     }
-    if (server.cluster_enabled) {
-        if (async) {
-            slotToKeyFlushAsync();
-        } else {
-            slotToKeyFlush();
+
+    /* Post-flush actions */
+    if (!backup) {
+        if (server.cluster_enabled) {
+            if (async) {
+                slotToKeyFlushAsync();
+            } else {
+                slotToKeyFlush();
+            }
         }
+        if (dbnum == -1) flushSlaveKeysWithExpireList();
+
+        /* Also fire the end event. Note that this event will fire almost
+         * immediately after the start event if the flush is asynchronous. */
+        moduleFireServerEvent(REDISMODULE_EVENT_FLUSHDB,
+                              REDISMODULE_SUBEVENT_FLUSHDB_END,
+                              &fi);
     }
-    if (dbnum == -1) flushSlaveKeysWithExpireList();
+
     return removed;
 }
 
+PORT_LONGLONG emptyDb(int dbnum, int flags, void(callback)(void*)) {
+    return emptyDbGeneric(server.db, dbnum, flags, callback);
+}
+
 int selectDb(client *c, int id) {
     if (id < 0 || id >= server.dbnum)
         return C_ERR;
@@ -386,6 +454,15 @@ int selectDb(client *c, int id) {
     return C_OK;
 }
 
+PORT_LONGLONG dbTotalServerKeyCount() {
+    PORT_LONGLONG total = 0;
+    int j;
+    for (j = 0; j < server.dbnum; j++) {
+        total += dictSize(server.db[j].dict);
+    }
+    return total;
+}
+
 /*-----------------------------------------------------------------------------
  * Hooks for key space changes.
  *
@@ -395,12 +472,16 @@ int selectDb(client *c, int id) {
  * Every time a DB is flushed the function signalFlushDb() is called.
  *----------------------------------------------------------------------------*/
 
-void signalModifiedKey(redisDb *db, robj *key) {
+/* Note that the 'c' argument may be NULL if the key was modified out of
+ * a context of a client. */
+void signalModifiedKey(client *c, redisDb *db, robj *key) {
     touchWatchedKey(db,key);
+    trackingInvalidateKey(c,key);
 }
 
 void signalFlushedDb(int dbid) {
     touchWatchedKeysOnFlush(dbid);
+    trackingInvalidateKeysOnFlush(dbid);
 }
 
 /*-----------------------------------------------------------------------------
@@ -429,32 +510,10 @@ int getFlushCommandFlags(client *c, int *flags) {
     return C_OK;
 }
 
-/* FLUSHDB [ASYNC]
- *
- * Flushes the currently SELECTed Redis DB. */
-void flushdbCommand(client *c) {
-    int flags;
-
-    if (getFlushCommandFlags(c,&flags) == C_ERR) return;
-    signalFlushedDb(c->db->id);
-    server.dirty += emptyDb(c->db->id,flags,NULL);
-    addReply(c,shared.ok);
-}
-
-/* FLUSHALL [ASYNC]
- *
- * Flushes the whole server data set. */
-void flushallCommand(client *c) {
-    int flags;
-
-    if (getFlushCommandFlags(c,&flags) == C_ERR) return;
-    signalFlushedDb(-1);
+/* Flushes the whole server data set. */
+void flushAllDataAndResetRDB(int flags) {
     server.dirty += emptyDb(-1,flags,NULL);
-    addReply(c,shared.ok);
-    if (server.rdb_child_pid != -1) {
-        IF_WIN32(AbortForkOperation(), kill(server.rdb_child_pid,SIGUSR1));
-        rdbRemoveTempFile(server.rdb_child_pid);
-    }
+    if (server.rdb_child_pid != -1) killRDBChild();
     if (server.saveparamslen > 0) {
         /* Normally rdbSave() will reset dirty, but we don't want this here
          * as otherwise FLUSHALL will not be replicated nor put into the AOF. */
@@ -465,6 +524,41 @@ void flushallCommand(client *c) {
         server.dirty = saved_dirty;
     }
     server.dirty++;
+#if defined(USE_JEMALLOC)
+    /* jemalloc 5 doesn't release pages back to the OS when there's no traffic.
+     * for large databases, flushdb blocks for long anyway, so a bit more won't
+     * harm and this way the flush and purge will be synchroneus. */
+    if (!(flags & EMPTYDB_ASYNC))
+        jemalloc_purge();
+#endif
+}
+
+/* FLUSHDB [ASYNC]
+ *
+ * Flushes the currently SELECTed Redis DB. */
+void flushdbCommand(client *c) {
+    int flags;
+
+    if (getFlushCommandFlags(c,&flags) == C_ERR) return;
+    server.dirty += emptyDb(c->db->id,flags,NULL);
+    addReply(c,shared.ok);
+#if defined(USE_JEMALLOC)
+    /* jemalloc 5 doesn't release pages back to the OS when there's no traffic.
+     * for large databases, flushdb blocks for long anyway, so a bit more won't
+     * harm and this way the flush and purge will be synchroneus. */
+    if (!(flags & EMPTYDB_ASYNC))
+        jemalloc_purge();
+#endif
+}
+
+/* FLUSHALL [ASYNC]
+ *
+ * Flushes the whole server data set. */
+void flushallCommand(client *c) {
+    int flags;
+    if (getFlushCommandFlags(c,&flags) == C_ERR) return;
+    flushAllDataAndResetRDB(flags);
+    addReply(c,shared.ok);
 }
 
 /* This command implements DEL and LAZYDEL. */
@@ -476,7 +570,7 @@ void delGenericCommand(client *c, int lazy) {
         int deleted  = lazy ? dbAsyncDelete(c->db,c->argv[j]) :
                               dbSyncDelete(c->db,c->argv[j]);
         if (deleted) {
-            signalModifiedKey(c->db,c->argv[j]);
+            signalModifiedKey(c,c->db,c->argv[j]);
             notifyKeyspaceEvent(NOTIFY_GENERIC,
                 "del",c->argv[j],c->db->id);
             server.dirty++;
@@ -487,7 +581,7 @@ void delGenericCommand(client *c, int lazy) {
 }
 
 void delCommand(client *c) {
-    delGenericCommand(c,0);
+    delGenericCommand(c,server.lazyfree_lazy_user_del);
 }
 
 void unlinkCommand(client *c) {
@@ -528,7 +622,7 @@ void randomkeyCommand(client *c) {
     robj *key;
 
     if ((key = dbRandomKey(c->db)) == NULL) {
-        addReply(c,shared.nullbulk);
+        addReplyNull(c);
         return;
     }
 
@@ -542,7 +636,7 @@ void keysCommand(client *c) {
     sds pattern = c->argv[1]->ptr;
     int plen = (int)sdslen(pattern), allkeys;
     PORT_ULONG numkeys = 0;
-    void *replylen = addDeferredMultiBulkLength(c);
+    void *replylen = addReplyDeferredLen(c);
 
     di = dictGetSafeIterator(c->db->dict);
     allkeys = (pattern[0] == '*' && plen == 1);
@@ -560,7 +654,7 @@ void keysCommand(client *c) {
         }
     }
     dictReleaseIterator(di);
-    setDeferredMultiBulkLength(c,replylen,numkeys);
+    setDeferredArrayLen(c,replylen,numkeys);
 }
 
 /* This callback is used by scanGenericCommand in order to collect elements
@@ -614,7 +708,7 @@ int parseScanCursorOrReply(client *c, robj *o, PORT_ULONG *cursor) {
 }
 
 /* This command implements SCAN, HSCAN and SSCAN commands.
- * If object 'o' is passed, then it must be a Hash or Set object, otherwise
+ * If object 'o' is passed, then it must be a Hash, Set or Zset object, otherwise
  * if 'o' is NULL the command will operate on the dictionary associated with
  * the current database.
  *
@@ -630,6 +724,7 @@ void scanGenericCommand(client *c, robj *o, PORT_ULONG cursor) {
     listNode *node, *nextnode;
     PORT_LONG count = 10;
     sds pat = NULL;
+    sds typename = NULL;
     int patlen = 0, use_pattern = 0;
     dict *ht;
 
@@ -666,6 +761,10 @@ void scanGenericCommand(client *c, robj *o, PORT_ULONG cursor) {
             use_pattern = !(pat[0] == '*' && patlen == 1);
 
             i += 2;
+        } else if (!strcasecmp(c->argv[i]->ptr, "type") && o == NULL && j >= 2) {
+            /* SCAN for a particular type only applies to the db dict */
+            typename = c->argv[i+1]->ptr;
+            i+= 2;
         } else {
             addReply(c,shared.syntaxerr);
             goto cleanup;
@@ -760,10 +859,17 @@ void scanGenericCommand(client *c, robj *o, PORT_ULONG cursor) {
             }
         }
 
+        /* Filter an element if it isn't the type we want. */
+        if (!filter && o == NULL && typename){
+            robj* typecheck = lookupKeyReadWithFlags(c->db, kobj, LOOKUP_NOTOUCH);
+            char* type = getObjectTypeName(typecheck);
+            if (strcasecmp((char*) typename, type)) filter = 1;
+        }
+
         /* Filter element if it is an expired key. */
         if (!filter && o == NULL && expireIfNeeded(c->db, kobj)) filter = 1;
 
-        /* Remove the element and its associted value if needed. */
+        /* Remove the element and its associated value if needed. */
         if (filter) {
             decrRefCount(kobj);
             listDelNode(keys, node);
@@ -785,10 +891,10 @@ void scanGenericCommand(client *c, robj *o, PORT_ULONG cursor) {
     }
 
     /* Step 4: Reply to the client. */
-    addReplyMultiBulkLen(c, 2);
+    addReplyArrayLen(c, 2);
     addReplyBulkLongLong(c,cursor);
 
-    addReplyMultiBulkLen(c, listLength(keys));
+    addReplyArrayLen(c, listLength(keys));
     while ((node = listFirst(keys)) != NULL) {
         robj *kobj = listNodeValue(node);
         addReplyBulk(c, kobj);
@@ -816,11 +922,8 @@ void lastsaveCommand(client *c) {
     addReplyLongLong(c,server.lastsave);
 }
 
-void typeCommand(client *c) {
-    robj *o;
-    char *type;
-
-    o = lookupKeyReadWithFlags(c->db,c->argv[1],LOOKUP_NOTOUCH);
+char* getObjectTypeName(robj *o) {
+    char* type;
     if (o == NULL) {
         type = "none";
     } else {
@@ -838,7 +941,13 @@ void typeCommand(client *c) {
         default: type = "unknown"; break;
         }
     }
-    addReplyStatus(c,type);
+    return type;
+}
+
+void typeCommand(client *c) {
+    robj *o;
+    o = lookupKeyReadWithFlags(c->db,c->argv[1],LOOKUP_NOTOUCH);
+    addReplyStatus(c, getObjectTypeName(o));
 }
 
 void shutdownCommand(client *c) {
@@ -893,8 +1002,8 @@ void renameGenericCommand(client *c, int nx) {
     dbAdd(c->db,c->argv[2],o);
     if (expire != -1) setExpire(c,c->db,c->argv[2],expire);
     dbDelete(c->db,c->argv[1]);
-    signalModifiedKey(c->db,c->argv[1]);
-    signalModifiedKey(c->db,c->argv[2]);
+    signalModifiedKey(c,c->db,c->argv[1]);
+    signalModifiedKey(c,c->db,c->argv[2]);
     notifyKeyspaceEvent(NOTIFY_GENERIC,"rename_from",
         c->argv[1],c->db->id);
     notifyKeyspaceEvent(NOTIFY_GENERIC,"rename_to",
@@ -962,6 +1071,13 @@ void moveCommand(client *c) {
 
     /* OK! key moved, free the entry in the source DB */
     dbDelete(src,c->argv[1]);
+    signalModifiedKey(c,src,c->argv[1]);
+    signalModifiedKey(c,dst,c->argv[1]);
+    notifyKeyspaceEvent(NOTIFY_GENERIC,
+                "move_from",c->argv[1],src->id);
+    notifyKeyspaceEvent(NOTIFY_GENERIC,
+                "move_to",c->argv[1],dst->id);
+
     server.dirty++;
     addReply(c,shared.cone);
 }
@@ -992,7 +1108,7 @@ void scanDatabaseForReadyLists(redisDb *db) {
  *
  * Returns C_ERR if at least one of the DB ids are out of range, otherwise
  * C_OK is returned. */
-int dbSwapDatabases(int id1, int id2) {
+int dbSwapDatabases(PORT_LONG id1, PORT_LONG id2) {
     if (id1 < 0 || id1 >= server.dbnum ||
         id2 < 0 || id2 >= server.dbnum) return C_ERR;
     if (id1 == id2) return C_OK;
@@ -1005,10 +1121,12 @@ int dbSwapDatabases(int id1, int id2) {
     db1->dict = db2->dict;
     db1->expires = db2->expires;
     db1->avg_ttl = db2->avg_ttl;
+    db1->expires_cursor = db2->expires_cursor;
 
     db2->dict = aux.dict;
     db2->expires = aux.expires;
     db2->avg_ttl = aux.avg_ttl;
+    db2->expires_cursor = aux.expires_cursor;
 
     /* Now we need to handle clients blocked on lists: as an effect
      * of swapping the two DBs, a client that was waiting for list
@@ -1048,6 +1166,8 @@ void swapdbCommand(client *c) {
         addReplyError(c,"DB index is out of range");
         return;
     } else {
+        RedisModuleSwapDbInfo si = {REDISMODULE_SWAPDBINFO_VERSION,id1,id2};
+        moduleFireServerEvent(REDISMODULE_EVENT_SWAPDB,0,&si);
         server.dirty++;
         addReply(c,shared.ok);
     }
@@ -1196,28 +1316,64 @@ int expireIfNeeded(redisDb *db, robj *key) {
     propagateExpire(db,key,server.lazyfree_lazy_expire);
     notifyKeyspaceEvent(NOTIFY_EXPIRED,
         "expired",key,db->id);
-    return server.lazyfree_lazy_expire ? dbAsyncDelete(db,key) :
-                                         dbSyncDelete(db,key);
+    int retval = server.lazyfree_lazy_expire ? dbAsyncDelete(db,key) :
+                                               dbSyncDelete(db,key);
+    if (retval) signalModifiedKey(NULL,db,key);
+    return retval;
 }
 
 /* -----------------------------------------------------------------------------
  * API to get key arguments from commands
  * ---------------------------------------------------------------------------*/
 
+/* Prepare the getKeysResult struct to hold numkeys, either by using the
+ * pre-allocated keysbuf or by allocating a new array on the heap.
+ *
+ * This function must be called at least once before starting to populate
+ * the result, and can be called repeatedly to enlarge the result array.
+ */
+int *getKeysPrepareResult(getKeysResult *result, int numkeys) {
+    /* GETKEYS_RESULT_INIT initializes keys to NULL, point it to the pre-allocated stack
+     * buffer here. */
+    if (!result->keys) {
+        serverAssert(!result->numkeys);
+        result->keys = result->keysbuf;
+    }
+
+    /* Resize if necessary */
+    if (numkeys > result->size) {
+        if (result->keys != result->keysbuf) {
+            /* We're not using a static buffer, just (re)alloc */
+            result->keys = zrealloc(result->keys, numkeys * sizeof(int));
+        } else {
+            /* We are using a static buffer, copy its contents */
+            result->keys = zmalloc(numkeys * sizeof(int));
+            if (result->numkeys)
+                memcpy(result->keys, result->keysbuf, result->numkeys * sizeof(int));
+        }
+        result->size = numkeys;
+    }
+
+    return result->keys;
+}
+
 /* The base case is to use the keys position as given in the command table
  * (firstkey, lastkey, step). */
-int *getKeysUsingCommandTable(struct redisCommand *cmd,robj **argv, int argc, int *numkeys) {
+int getKeysUsingCommandTable(struct redisCommand *cmd,robj **argv, int argc, getKeysResult *result) {
     int j, i = 0, last, *keys;
     UNUSED(argv);
 
     if (cmd->firstkey == 0) {
-        *numkeys = 0;
-        return NULL;
+        result->numkeys = 0;
+        return 0;
     }
 
     last = cmd->lastkey;
     if (last < 0) last = argc+last;
-    keys = zmalloc(sizeof(int)*(((PORT_ULONG) last - cmd->firstkey)+1));  WIN_PORT_FIX /* cat (PORT_ULONG) */
+
+    int count = ((last - cmd->firstkey)+1);
+    keys = getKeysPrepareResult(result, count);
+
     for (j = cmd->firstkey; j <= last; j += cmd->keystep) {
         if (j >= argc) {
             /* Modules commands, and standard commands with a not fixed number
@@ -1227,23 +1383,23 @@ int *getKeysUsingCommandTable(struct redisCommand *cmd,robj **argv, int argc, in
              * return no keys and expect the command implementation to report
              * an arity or syntax error. */
             if (cmd->flags & CMD_MODULE || cmd->arity < 0) {
-                zfree(keys);
-                *numkeys = 0;
-                return NULL;
+                getKeysFreeResult(result);
+                result->numkeys = 0;
+                return 0;
             } else {
                 serverPanic("Redis built-in command declared keys positions not matching the arity requirements.");
             }
         }
         keys[i++] = j;
     }
-    *numkeys = i;
-    return keys;
+    result->numkeys = i;
+    return i;
 }
 
 /* Return all the arguments that are keys in the command passed via argc / argv.
  *
  * The command returns the positions of all the key arguments inside the array,
- * so the actual return value is an heap allocated array of integers. The
+ * so the actual return value is a heap allocated array of integers. The
  * length of the array is returned by reference into *numkeys.
  *
  * 'cmd' must be point to the corresponding entry into the redisCommand
@@ -1251,25 +1407,26 @@ int *getKeysUsingCommandTable(struct redisCommand *cmd,robj **argv, int argc, in
  *
  * This function uses the command table if a command-specific helper function
  * is not required, otherwise it calls the command-specific function. */
-int *getKeysFromCommand(struct redisCommand *cmd, robj **argv, int argc, int *numkeys) {
+int getKeysFromCommand(struct redisCommand *cmd, robj **argv, int argc, getKeysResult *result) {
     if (cmd->flags & CMD_MODULE_GETKEYS) {
-        return moduleGetCommandKeysViaAPI(cmd,argv,argc,numkeys);
+        return moduleGetCommandKeysViaAPI(cmd,argv,argc,result);
     } else if (!(cmd->flags & CMD_MODULE) && cmd->getkeys_proc) {
-        return cmd->getkeys_proc(cmd,argv,argc,numkeys);
+        return cmd->getkeys_proc(cmd,argv,argc,result);
     } else {
-        return getKeysUsingCommandTable(cmd,argv,argc,numkeys);
+        return getKeysUsingCommandTable(cmd,argv,argc,result);
     }
 }
 
 /* Free the result of getKeysFromCommand. */
-void getKeysFreeResult(int *result) {
-    zfree(result);
+void getKeysFreeResult(getKeysResult *result) {
+    if (result && result->keys != result->keysbuf)
+        zfree(result->keys);
 }
 
 /* Helper function to extract keys from following commands:
  * ZUNIONSTORE <destkey> <num-keys> <key> <key> ... <key> <options>
  * ZINTERSTORE <destkey> <num-keys> <key> <key> ... <key> <options> */
-int *zunionInterGetKeys(struct redisCommand *cmd, robj **argv, int argc, int *numkeys) {
+int zunionInterGetKeys(struct redisCommand *cmd, robj **argv, int argc, getKeysResult *result) {
     int i, num, *keys;
     UNUSED(cmd);
 
@@ -1277,28 +1434,30 @@ int *zunionInterGetKeys(struct redisCommand *cmd, robj **argv, int argc, int *nu
     /* Sanity check. Don't return any key if the command is going to
      * reply with syntax error. */
     if (num < 1 || num > (argc-3)) {
-        *numkeys = 0;
-        return NULL;
+        result->numkeys = 0;
+        return 0;
     }
 
     /* Keys in z{union,inter}store come from two places:
      * argv[1] = storage key,
      * argv[3...n] = keys to intersect */
-    keys = zmalloc(sizeof(int)*((PORT_ULONG)num+1));  WIN_PORT_FIX /* cast (PORT_ULONG) */
+    /* Total keys = {union,inter} keys + storage key */
+    keys = getKeysPrepareResult(result, num+1);
+    result->numkeys = num+1;
 
     /* Add all key positions for argv[3...n] to keys[] */
     for (i = 0; i < num; i++) keys[i] = 3+i;
 
     /* Finally add the argv[1] key position (the storage key target). */
     keys[num] = 1;
-    *numkeys = num+1;  /* Total keys = {union,inter} keys + storage key */
-    return keys;
+
+    return result->numkeys;
 }
 
 /* Helper function to extract keys from the following commands:
  * EVAL <script> <num-keys> <key> <key> ... <key> [more stuff]
  * EVALSHA <script> <num-keys> <key> <key> ... <key> [more stuff] */
-int *evalGetKeys(struct redisCommand *cmd, robj **argv, int argc, int *numkeys) {
+int evalGetKeys(struct redisCommand *cmd, robj **argv, int argc, getKeysResult *result) {
     int i, num, *keys;
     UNUSED(cmd);
 
@@ -1306,17 +1465,17 @@ int *evalGetKeys(struct redisCommand *cmd, robj **argv, int argc, int *numkeys)
     /* Sanity check. Don't return any key if the command is going to
      * reply with syntax error. */
     if (num <= 0 || num > (argc-3)) {
-        *numkeys = 0;
-        return NULL;
+        result->numkeys = 0;
+        return 0;
     }
 
-    keys = zmalloc(sizeof(int)*num);
-    *numkeys = num;
+    keys = getKeysPrepareResult(result, num);
+    result->numkeys = num;
 
     /* Add all key positions for argv[3...n] to keys[] */
     for (i = 0; i < num; i++) keys[i] = 3+i;
 
-    return keys;
+    return result->numkeys;
 }
 
 /* Helper function to extract keys from the SORT command.
@@ -1326,13 +1485,12 @@ int *evalGetKeys(struct redisCommand *cmd, robj **argv, int argc, int *numkeys)
  * The first argument of SORT is always a key, however a list of options
  * follow in SQL-alike style. Here we parse just the minimum in order to
  * correctly identify keys in the "STORE" option. */
-int *sortGetKeys(struct redisCommand *cmd, robj **argv, int argc, int *numkeys) {
+int sortGetKeys(struct redisCommand *cmd, robj **argv, int argc, getKeysResult *result) {
     int i, j, num, *keys, found_store = 0;
     UNUSED(cmd);
 
     num = 0;
-    keys = zmalloc(sizeof(int)*2); /* Alloc 2 places for the worst case. */
-
+    keys = getKeysPrepareResult(result, 2); /* Alloc 2 places for the worst case. */
     keys[num++] = 1; /* <sort-key> is always present. */
 
     /* Search for STORE option. By default we consider options to don't
@@ -1364,11 +1522,11 @@ int *sortGetKeys(struct redisCommand *cmd, robj **argv, int argc, int *numkeys)
             }
         }
     }
-    *numkeys = num + found_store;
-    return keys;
+    result->numkeys = num + found_store;
+    return result->numkeys;
 }
 
-int *migrateGetKeys(struct redisCommand *cmd, robj **argv, int argc, int *numkeys) {
+int migrateGetKeys(struct redisCommand *cmd, robj **argv, int argc, getKeysResult *result) {
     int i, num, first, *keys;
     UNUSED(cmd);
 
@@ -1389,17 +1547,17 @@ int *migrateGetKeys(struct redisCommand *cmd, robj **argv, int argc, int *numkey
         }
     }
 
-    keys = zmalloc(sizeof(int)*num);
+    keys = getKeysPrepareResult(result, num);
     for (i = 0; i < num; i++) keys[i] = first+i;
-    *numkeys = num;
-    return keys;
+    result->numkeys = num;
+    return num;
 }
 
 /* Helper function to extract keys from following commands:
  * GEORADIUS key x y radius unit [WITHDIST] [WITHHASH] [WITHCOORD] [ASC|DESC]
  *                             [COUNT count] [STORE key] [STOREDIST key]
  * GEORADIUSBYMEMBER key member radius unit ... options ... */
-int *georadiusGetKeys(struct redisCommand *cmd, robj **argv, int argc, int *numkeys) {
+int georadiusGetKeys(struct redisCommand *cmd, robj **argv, int argc, getKeysResult *result) {
     int i, num, *keys;
     UNUSED(cmd);
 
@@ -1422,20 +1580,60 @@ int *georadiusGetKeys(struct redisCommand *cmd, robj **argv, int argc, int *numk
      * argv[1] = key,
      * argv[5...n] = stored key if present
      */
-    keys = zmalloc(sizeof(int) * num);
+    keys = getKeysPrepareResult(result, num);
 
     /* Add all key positions to keys[] */
     keys[0] = 1;
     if(num > 1) {
          keys[1] = stored_key;
     }
-    *numkeys = num;
-    return keys;
+    result->numkeys = num;
+    return num;
+}
+
+/* LCS ... [KEYS <key1> <key2>] ... */
+int lcsGetKeys(struct redisCommand *cmd, robj **argv, int argc, getKeysResult *result) {
+    int i;
+    int *keys = getKeysPrepareResult(result, 2);
+    UNUSED(cmd);
+
+    /* We need to parse the options of the command in order to check for the
+     * "KEYS" argument before the "STRINGS" argument. */
+    for (i = 1; i < argc; i++) {
+        char *arg = argv[i]->ptr;
+        int moreargs = (argc-1) - i;
+
+        if (!strcasecmp(arg, "strings")) {
+            break;
+        } else if (!strcasecmp(arg, "keys") && moreargs >= 2) {
+            keys[0] = i+1;
+            keys[1] = i+2;
+            result->numkeys = 2;
+            return result->numkeys;
+        }
+    }
+    result->numkeys = 0;
+    return result->numkeys;
+}
+
+/* Helper function to extract keys from memory command.
+ * MEMORY USAGE <key> */
+int memoryGetKeys(struct redisCommand *cmd, robj **argv, int argc, getKeysResult *result) {
+    UNUSED(cmd);
+
+    getKeysPrepareResult(result, 1);
+    if (argc >= 3 && !strcasecmp(argv[1]->ptr,"usage")) {
+        result->keys[0] = 2;
+        result->numkeys = 1;
+        return result->numkeys;
+    }
+    result->numkeys = 0;
+    return 0;
 }
 
 /* XREAD [BLOCK <milliseconds>] [COUNT <count>] [GROUP <groupname> <ttl>]
  *       STREAMS key_1 key_2 ... key_N ID_1 ID_2 ... ID_N */
-int *xreadGetKeys(struct redisCommand *cmd, robj **argv, int argc, int *numkeys) {
+int xreadGetKeys(struct redisCommand *cmd, robj **argv, int argc, getKeysResult *result) {
     int i, num = 0, *keys;
     UNUSED(cmd);
 
@@ -1465,33 +1663,33 @@ int *xreadGetKeys(struct redisCommand *cmd, robj **argv, int argc, int *numkeys)
 
     /* Syntax error. */
     if (streams_pos == -1 || num == 0 || num % 2 != 0) {
-        *numkeys = 0;
-        return NULL;
+        result->numkeys = 0;
+        return 0;
     }
     num /= 2; /* We have half the keys as there are arguments because
                  there are also the IDs, one per key. */
 
-    keys = zmalloc(sizeof(int) * num);
+    keys = getKeysPrepareResult(result, num);
     for (i = streams_pos+1; i < argc-num; i++) keys[i-streams_pos-1] = i;
-    *numkeys = num;
-    return keys;
+    result->numkeys = num;
+    return num;
 }
 
 /* Slot to Key API. This is used by Redis Cluster in order to obtain in
  * a fast way a key that belongs to a specified hash slot. This is useful
  * while rehashing the cluster and in other conditions when we need to
  * understand if we have keys for a given hash slot. */
-void slotToKeyUpdateKey(robj *key, int add) {
-    unsigned int hashslot = keyHashSlot(key->ptr,sdslen(key->ptr));
+void slotToKeyUpdateKey(sds key, int add) {
+    size_t keylen = sdslen(key);
+    unsigned int hashslot = keyHashSlot(key,keylen);
     unsigned char buf[64];
     unsigned char *indexed = buf;
-    size_t keylen = sdslen(key->ptr);
 
     server.cluster->slots_keys_count[hashslot] += add ? 1 : -1;
     if (keylen+2 > 64) indexed = zmalloc(keylen+2);
     indexed[0] = (hashslot >> 8) & 0xff;
     indexed[1] = hashslot & 0xff;
-    memcpy(indexed+2,key->ptr,keylen);
+    memcpy(indexed+2,key,keylen);
     if (add) {
         raxInsert(server.cluster->slots_to_keys,indexed,keylen+2,NULL,NULL);
     } else {
@@ -1500,11 +1698,11 @@ void slotToKeyUpdateKey(robj *key, int add) {
     if (indexed != buf) zfree(indexed);
 }
 
-void slotToKeyAdd(robj *key) {
+void slotToKeyAdd(sds key) {
     slotToKeyUpdateKey(key,1);
 }
 
-void slotToKeyDel(robj *key) {
+void slotToKeyDel(sds key) {
     slotToKeyUpdateKey(key,0);
 }