dmbarbour@gmail.com wrote:

Full_Name: David Barbour Version: LMDB 0.9.10 OS: Ubuntu URL: ftp://ftp.openldap.org/incoming/ Submission from: (NULL) (2602:306:80bb:160:d913:da7:da0f:76b3)

As discussed on the list [1], I believe access to the current transaction ID could be very useful for layering features above LMDB, such as concurrent writers, read-only to read-write promotion, or serving as an e-tag for polling.

A patch David-Barbour-141205.patch has been uploaded and includes a disclaimer to public-domain.

[1] http://www.openldap.org/lists/openldap-devel/201412/msg00000.html

Thanks. There's a slight problem with the patch, your function returns MDB_txnid_t but that is a private typedef in mdb.c. It is not defined in lmdb.h, so no one will be able to compile and use this code.

Easiest change would be to just return size_t, like MDB_envinfo uses.