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Diffstat (limited to 'man/man5/lmdb_table.5')
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diff --git a/man/man5/lmdb_table.5 b/man/man5/lmdb_table.5 new file mode 100644 index 0000000..b324f76 --- /dev/null +++ b/man/man5/lmdb_table.5 @@ -0,0 +1,142 @@ +.TH LMDB_TABLE 5 +.ad +.fi +.SH NAME +lmdb_table +\- +Postfix LMDB adapter +.SH "SYNOPSIS" +.na +.nf +\fBpostmap lmdb:/etc/postfix/\fIfilename\fR +.br +\fBpostmap \-i lmdb:/etc/postfix/\fIfilename\fB <\fIinputfile\fR + +\fBpostmap \-d "\fIkey\fB" lmdb:/etc/postfix/\fIfilename\fR +.br +\fBpostmap \-d \- lmdb:/etc/postfix/\fIfilename\fB <\fIinputfile\fR + +\fBpostmap \-q "\fIkey\fB" lmdb:/etc/postfix/\fIfilename\fR +.br +\fBpostmap \-q \- lmdb:/etc/postfix/\fIfilename\fB <\fIinputfile\fR +.SH DESCRIPTION +.ad +.fi +The Postfix LMDB adapter provides access to a persistent, +memory\-mapped, key\-value store. The database size is limited +only by the size of the memory address space (typically 31 +or 47 bits on 32\-bit or 64\-bit CPUs, respectively) and by +the available file system space. +.SH "REQUESTS" +.na +.nf +.ad +.fi +The LMDB adapter supports all Postfix lookup table operations. +This makes LMDB suitable for Postfix address rewriting, +routing, access policies, caches, or any information 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 table lookups may 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, for +example, btree:, hash:, or ldap: tables. + +Unlike other flat\-file Postfix databases, changes to +an LMDB database do not trigger automatic daemon program +restart, and do not require "\fBpostfix reload\fR". +.SH "RELIABILITY" +.na +.nf +.ad +.fi +LMDB's copy\-on\-write architecture provides safe 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 +corruption due to stray pointer bugs. + +Multiple processes can safely update an LMDB database without +serializing requests through the proxymap(8) service. This +makes LMDB suitable as a shared cache for verify(8) or +postscreen(8) services. +.SH "SYNCHRONIZATION" +.na +.nf +.ad +.fi +The Postfix LMDB adapter does not use LMDB's built\-in locking +scheme, because that would require world\-writable lockfiles +and would violate the Postfix security model. Instead, +Postfix uses fcntl(2) locks with whole\-file granularity. +Programs that use LMDB's built\-in locking protocol will +corrupt a Postfix LMDB database or will read garbage. + +Every Postfix LMDB database read or write transaction must +be protected from start to end with a shared or exclusive +fcntl(2) lock. A writer may atomically downgrade an exclusive +lock to a shared lock, but it must hold an exclusive lock +while opening another write transaction. + +Note that fcntl(2) locks do not protect transactions within +the same process against each other. If a program cannot +avoid making simultaneous database requests, then it must +protect its transactions with in\-process locks, in addition +to the per\-process fcntl(2) locks. +.SH "CONFIGURATION PARAMETERS" +.na +.nf +.ad +.fi +Short\-lived programs automatically pick up changes to +main.cf. With long\-running daemon programs, Use the command +"\fBpostfix reload\fR" after a configuration change. +.IP "\fBlmdb_map_size (default: 16777216)\fR" +The initial LMDB database size limit in bytes. +.SH "SEE ALSO" +.na +.nf +postconf(1), Postfix supported lookup tables +postmap(1), Postfix lookup table maintenance +postconf(5), configuration parameters +.SH "README FILES" +.na +.nf +.ad +.fi +Use "\fBpostconf readme_directory\fR" or +"\fBpostconf html_directory\fR" to locate this information. +.na +.nf +DATABASE_README, Postfix lookup table overview +LMDB_README, Postfix OpenLDAP LMDB howto +.SH "LICENSE" +.na +.nf +.ad +.fi +The Secure Mailer license must be distributed with this software. +.SH HISTORY +.ad +.fi +LMDB support was introduced with Postfix version 2.11. +.SH "AUTHOR(S)" +.na +.nf +Howard Chu +Symas Corporation + +Wietse Venema +IBM T.J. Watson Research +P.O. Box 704 +Yorktown Heights, NY 10598, USA + +Wietse Venema +Google, Inc. +111 8th Avenue +New York, NY 10011, USA |