Alias_entry_cache_negative, alias_entry_cache_size, alias_entry_cache_timeout MTA options

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LDAP and URL lookup cache options (alias_entry_cache_negative, alias_entry_cache_size, alias_entry_cache_timeout)

The alias_entry_cache_* options:

alias_entry_cache_negative (0 or 1)
alias_entry_cache_size (integer)
alias_entry_cache_timeout (integer)

control some performance tuning relevant when operating in direct LDAP mode, in particular when alias_urln options are being used. When alias_urln lookups are performed, the results can be cached; that is, an in memory cache is maintained of the results of "recent" such lookups. There is a trade-off between performance on the one hand, vs. memory usage and speed with which changes to the LDAP entries take effect on the other hand.

In particular, the alias_entry_cache_negative option, which takes a boolean argument and defaults to 0 (false), controls whether or not negative results (that is, failures to find an alias) are cached.

Related options include: The alias_entry_cache_size option, which takes an integer argument and defaults to 1000, controls how many results are cached. The alias_entry_cache_timeout option, which takes an integer argument and defaults to 600, specifies how long in seconds to maintain cache results.

See also: alias_entry_cache_* options, alias_entry_cache_size, alias_entry_cache_timeout, MTA options, Option value syntax, Getting option changes to take effect, MTA options, listed alphabetically, MTA options, listed by functional groups, LDAP and URL lookup cache options, Direct LDAP user/group lookup options.