(ITS#8191) mdb_txn_commit(empty txn) does not sync

[h.b.furuseth@usit.uio.no]

Full_Name: Hallvard B Furuseth
Version: LMDB_0.9.15
OS: 
URL: 
Submission from: (NULL) (81.191.45.5)
Submitted by: hallvard


mdb_txn_commit(txn which made no changes) does not mdb_env_sync(),
but lmdb.h says several times that Commit flushes buffers to disk.


My feeling is that this is a quirk the user should not need to
know about, and it's cleaner to sy r rather than to document it.

OTOH I don't know if "fast commit of no-change txns" is a feature
which someone expects to work, and if sync can be expensive even
when there is no new data to flush. (I don't know what BDB does.)