Abilio Marques wrote:
I've successfully ported a particular piece of software from multiple plain files in
disk to LMDB. There were multiple reasons to do so (i.e., performance and
The program is making individual calls to a storage API, that in turn creates files or
reads them (through a cache). There is no concept of transaction. For
performance and lifetime reasons, the original code avoids to perform a fsync every time
it writes to a file by queuing renames (for atomic writes) and deletes,
which in turn are executed by a background thread after 2 seconds idling (or a max of 15
sec after first write/delete).
Replacing such a monster "files + cache" with LMDB was a breeze. I kept the API
intact, and to deal with the price of fsyncs, I thought of opening with
MDB_NOSYNC, and sync after 2 seconds of inactivity.
As documented, MDB_NOSYNC is only safe for power failure if the filesystem guarantees that
it preserves the order of writes.
Otherwise all bets are off.
-- Howard Chu
CTO, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc/
Chief Architect, OpenLDAP http://www.openldap.org/project/