Bron Gondwana via Cyrus-devel wrote:
I'm going to try to build an LMDB backend. I do have some questions for
Howard about how best to do it... :) The CyrusDB abstraction layer allows opening multiple databases by filename. Should we be opening one environment per file, or just a single environment per process? Looking at:
The preferred usage model is to use a single environment per process. It simplifies choosing the env mapsize, just use one very large number. With individual environments per file, you are required to think about how big each file can be relative to each other. Better to avoid that complexity.
http://lmdb.tech/doc/starting.html We could us MDB_NOSUBDIR to use the file path as a data file via mdb_env_open... We already use internal "open file" tracking in most of our database types,
so I'd add that for the LMDB backend as well. I just use a linked list, since we tend to have at most 3-4 databases open at once in each process.
We don't use threading for anything except mupdate, and that uses a mutex
around all the database access, so multiple thread synchronisation should be OK :)
Bron.
-- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/
