LMDB_TABLE(5)                                                    LMDB_TABLE(5)

NAME
       lmdb_table - Postfix LMDB adapter

SYNOPSIS
       postmap lmdb:/etc/postfix/filename
       postmap -i lmdb:/etc/postfix/filename <inputfile

       postmap -d "key" lmdb:/etc/postfix/filename
       postmap -d - lmdb:/etc/postfix/filename <inputfile

       postmap -q "key" lmdb:/etc/postfix/filename
       postmap -q - lmdb:/etc/postfix/filename <inputfile

DESCRIPTION
       The  Postfix LMDB adapter provides access to a persistent,
       memory-mapped, key-value store.  The database size is lim-
       ited only by the size of the memory address space and file
       system.

REQUESTS
       The LMDB adapter supports all Postfix lookup table  opera-
       tions.   This  makes  LMDB  suitable  for  Postfix address
       rewriting, routing, access policies, caches, or any infor-
       mation that can be stored under a fixed lookup key.

       When  a  transaction fails due to a full database, Postfix
       resizes the database and retries the transaction.

       Postfix access, address mapping and  routing  tables  will
       generate  partial search keys such as domain names without
       one or more subdomains, network addresses without  one  or
       more  least-significant octets, or email addresses without
       the localpart, address extension or domain portion.   This
       behavior  is  also  found  with  btree:,  hash:,  or ldap:
       tables.

       Unlike other flat-file based Postfix databases, changes to
       an  LMDB  database do not require automatic daemon program
       restart.

RELIABILITY
       LMDB's  copy-on-write   architecture   achieves   reliable
       updates,  at  the cost of using more space than some other
       flat-file databases.  Read  operations  are  memory-mapped
       for  speed.   Write  operations  are  not memory-mapped to
       avoid silent curruption due stray pointer bugs.

       The Postfix LMDB adapter implements locking with  fcntl(2)
       locks  at  whole-file  granularity.  LMDB's native locking
       scheme would require world-writable  lockfiles  and  would
       therefore violate the Postfix security model.  Unlike some
       other Postfix  flat-file  databases,  LMDB  databases  can
       safely be updated without serializing requests through the
       proxymap(8) service.

CONFIGURATION PARAMETERS
       Short-lived programs  automatically  pick  up  changes  to
       main.cf.   With long-running daemon programs, Use the com-
       mand "postfix reload" after a configuration change.

       lmdb_map_size (default: 16777216)
              The initial OpenLDAP LMDB database  size  limit  in
              bytes.

SEE ALSO
       postconf(1), Postfix supported lookup tables
       postmap(1), Postfix lookup table maintenance
       postconf(5), configuration parameters

README FILES
       DATABASE_README, Postfix lookup table overview
       LMDB_README, Postfix LMDB howto

LICENSE
       The Secure Mailer license must be  distributed  with  this
       software.

HISTORY
       LMDB support was introduced with Postfix version 2.11.

AUTHOR(S)
       Howard Chu
       Symas Corporation

       Wietse Venema
       IBM T.J. Watson Research
       P.O. Box 704
       Yorktown Heights, NY 10598, USA

                                                                 LMDB_TABLE(5)