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Creating an LMDB database in Python · Deep learning at the University of Chicago
LMDB is the database of choice when using Caffe with large datasets. This is a tutorial of how to create an LMDB database from Python. First, let’s look at the pros and cons of using LMDB over HDF5.

Reasons to use HDF5:

Simple format to read/write.
Reasons to use LMDB:

LMDB uses memory-mapped files, giving much better I/O performance.
Works well with really large datasets. The HDF5 files are always read entirely into memory, so you can’t have any HDF5 file exceed your memory capacity. You can easily split your data into several HDF5 files though (just put several paths to h5 files in your text file). Then again, compared to LMDB’s page caching the I/O performance won’t be nearly as good.
python  lmdb  hdf5  database 
june 2017 by griddell
lmdb — lmdb 0.92 documentation
LMDB is a tiny database with some excellent properties:

Ordered map interface (keys are always lexicographically sorted).
Reader/writer transactions: readers don’t block writers, writers don’t block readers. Each environment supports one concurrent write transaction.
Read transactions are extremely cheap.
Environments may be opened by multiple processes on the same host, making it ideal for working around Python’s GIL.
Multiple named databases may be created with transactions covering all named databases.
Memory mapped, allowing for zero copy lookup and iteration. This is optionally exposed to Python using the buffer() interface.
Maintenance requires no external process or background threads.
No application-level caching is required: LMDB fully exploits the operating system’s buffer cache.
python  lmdb  database 
april 2017 by griddell
LDAP at Lightning Speed - LMDB
Howard Chu covers highlights of the LMDB design and discusses some of the internal improvements in slapd due to LMDB, as well as the impact of LMDB on other projects.
lmdb  rocksdb 
december 2016 by vdm
Twitter
Using to write a HUGE dataset into . Its quite fast processing 16bit ima…
LMDB  deeplearning  from twitter_favs
november 2016 by kyosha
Gmane -- RE: newstore direction
For people who can do math - LSM write-amp is O(N^2). B+tree write amp is essentially O(1).
LMDB  LevelDB  RocksDB  from twitter_favs
october 2015 by avifreedman

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