SORT ALPHA: use collation instead of binary comparison.

Note that we only do it when STORE is not used, otherwise we want an
absolutely locale independent and binary safe sorting in order to ensure
AOF / replication consistency.

This is probably an unexpected behavior violating the least surprise
rule, but there is currently no other simple / good alternative.

src/redis.h

@@ -891,6 +891,7 @@ struct redisServer {
     int sort_desc;
     int sort_alpha;
     int sort_bypattern;
+    int sort_store;
     /* Zip structure config, see redis.conf for more information  */
     size_t hash_max_ziplist_entries;
     size_t hash_max_ziplist_value;

src/sort.c

@@ -163,12 +163,22 @@ int sortCompare(const void *s1, const void *s2) {
                 else
                     cmp = 1;
             } else {
-                /* We have both the objects, use strcoll */
-                cmp = strcoll(so1->u.cmpobj->ptr,so2->u.cmpobj->ptr);
+                /* We have both the objects, compare them. */
+                if (server.sort_store) {
+                    cmp = compareStringObjects(so1->u.cmpobj,so2->u.cmpobj);
+                } else {
+                    /* Here we can use strcoll() directly as we are sure that
+                     * the objects are decoded string objects. */
+                    cmp = strcoll(so1->u.cmpobj->ptr,so2->u.cmpobj->ptr);
+                }
             }
         } else {
             /* Compare elements directly. */
-            cmp = compareStringObjects(so1->obj,so2->obj);
+            if (server.sort_store) {
+                cmp = compareStringObjects(so1->obj,so2->obj);
+            } else {
+                cmp = collateStringObjects(so1->obj,so2->obj);
+            }
         }
     }
     return server.sort_desc ? -cmp : cmp;
@@ -432,6 +442,7 @@ void sortCommand(redisClient *c) {
         server.sort_desc = desc;
         server.sort_alpha = alpha;
         server.sort_bypattern = sortby ? 1 : 0;
+        server.sort_store = storekey ? 1 : 0;
         if (sortby && (start != 0 || end != vectorlen-1))
             pqsort(vector,vectorlen,sizeof(redisSortObject),sortCompare, start,end);
         else