On 12 Jun 2013, at 14:12, [email protected] wrote: > In this example, instead of 5 queries (in reality each with 1-2 joins) it is > only a single query and even easier to read/work with.
http://www.exim.org/exim-html-current/doc/html/spec_html/ch-file_and_database_lookups.html "8. Lookup caching Exim caches all lookup results in order to avoid needless repetition of lookups. However, because (apart from the daemon) Exim operates as a collection of independent, short-lived processes, this caching applies only within a single Exim process. There is no inter-process lookup caching facility." So, in the first router, if you did a query which SELECTed multiple records then that would be saved into address_data. If the *exact same* lookup happened in sequential routers, the cached results would be used - thus cutting the number of queries. If however the query was spawned from a different process (as can happen with redirection or multiple deliveries with breaks on the queue), additional queries will take place. Graeme -- ## List details at https://lists.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://wiki.exim.org/
