LMDB is an ultra-fast, ultra-compact key-value data
store developed by Symas for the OpenLDAP Project.
It uses memory-mapped files, so it has the read
performance of a pure in-memory database while still
offering the persistence of standard disk-based
databases, and is only limited to the size of the
virtual address space, (it is not limited to the
size of physical RAM). LMDB was originally called
MDB, but was renamed to avoid confusion with other
software associated with the name MDB.
LMDB 1.0 introduced an incompatible on-disk file format change.
Databases created with LMDB 0.9.x cannot be opened with LMDB 1.0.
If you are migrating from LMDB 0.9.x, you must export your existing
databases using the old mdb_dump and re-import them with the new
mdb_load:
# mdb_dump -a /path/to/db > /tmp/mydb.dump
# mdb_load -f /tmp/mydb.dump /path/to/newdb
There is no support in LMDB 1.0 for operating directly on v0.9 DB files.
If upgrading from < 1.0.0:
LMDB 1.0 introduced an incompatible on-disk file format change.
Databases created with LMDB 0.9.x cannot be opened with LMDB 1.0.
Before using the new library, export your existing databases using the
old mdb_dump utility and re-import them with the new mdb_load:
# mdb_dump -a /path/to/db > /tmp/mydb.dump
# mdb_load -f /tmp/mydb.dump /path/to/newdb
There is no support in LMDB 1.0 for operating directly on v0.9 DB files.
