Russell Haley wrote:
I wasn't fully subscribed when I sent this so I'll send it again.
Any input or reference hints would be great. I love reading manuals. :)
---------- Forwarded message ----------
From: Russell Haley <russ.ha...@gmail.com>
Date: Tue, Sep 20, 2016 at 4:52 PM
Subject: Using lmdb as a pure in memory store
We are currently evaluating in memory key value stores for ~100,000 -
200,000 records in an embedded system. I suggested lmdb but it is
being discounted for some reasons I thought I'd validate:
1) It is currently thought that a on disk file is REQUIRED for the
system. Does MDB_NOSYNC turn off the disk caching? Can it be run as a
pure in-memory database? Could the file not just be mapped to a
A file is required. Whether the file is on-disk or not is irrelevant. It can
of course be on a RAMdisk (or, in Linux, a tmpfs), which would then make it
MDB_NOSYNC turns off syncing, that's why it is named that.
2) Because these values can come very fast, that the use of a lock
file would cause delay and too much wear on the nand based disk (SSD).
No. That's not how the lock file is used.
I see a no locking option ( MDB_NOLOCK) that would stop a lock file
This option should only be used if you're implementing your own lock manager.
Hint - no matter what approach you use, any other lock manager you use will be
slower than LMDB's.
Again, another option would be mapping the lock file to
a memdisk to handle that?
-- Howard Chu
CTO, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc/
Chief Architect, OpenLDAP http://www.openldap.org/project/