Added details about 'lmdb-sync-mode=sync' option

diff --git a/docs/backends/lmdb.rst b/docs/backends/lmdb.rst
index d63d0735756921136e45c3793537864629f8c87c..5169fbda716d3bfd2bf22b387735fd19bf33b738 100644 (file)
--- a/docs/backends/lmdb.rst
+++ b/docs/backends/lmdb.rst
@@ -45,8 +45,9 @@ Default is 2 on 32 bits systems, and 64 on 64 bits systems.
 ``lmdb-sync-mode``
 ^^^^^^^^^^^^^^^^^
 
-Synchronisation mode: nosync, nometasync, mapasync
+Synchronisation mode: sync, nosync, nometasync, mapasync
 
+* ``sync``: LMDB synchronous mode. Safest option, but also slightly slower. Can  also be enabled with ``lmdb-sync-mode=`` 
 * ``nosync``: don't flush systems buffers to disk when committing a transation.
   This means a system crash can corrupt the database or lose the last transactions if buffers are not yet flushed to disk.
 * ``nometasync``: flush system buffers to disk only once per transaction, omit the metadata flush. This maintains database integrity, but can potentially lose the last committed transaction if the operating system crashes.