Update WRITEMAP doc

diff --git a/libraries/liblmdb/lmdb.h b/libraries/liblmdb/lmdb.h
index 8323af5ec0bd653693f9d541650da89da02f7302..0855da8e46e0f8553717d2d9dcc95ce482042cb7 100644 (file)
--- a/libraries/liblmdb/lmdb.h
+++ b/libraries/liblmdb/lmdb.h
@@ -529,9 +529,11 @@ int  mdb_env_create(MDB_env **env);
         *              allowed. LMDB will still modify the lock file - except on read-only
         *              filesystems, where LMDB does not use locks.
         *      <li>#MDB_WRITEMAP
-        *              Use a writeable memory map unless MDB_RDONLY is set. This is faster
-        *              and uses fewer mallocs, but loses protection from application bugs
+        *              Use a writeable memory map unless MDB_RDONLY is set. This uses
+        *              fewer mallocs but loses protection from application bugs
         *              like wild pointer writes and other bad updates into the database.
+        *              This may be slightly faster for DBs that fit entirely in RAM, but
+        *              is slower for DBs larger than RAM.
         *              Incompatible with nested transactions.
         *              Do not mix processes with and without MDB_WRITEMAP on the same
         *              environment.  This can defeat durability (#mdb_env_sync etc).