Robert Blayzor wrote:
When using Exim to pull domainlists, say:
domainlist db_localdoms = pgsql;.... domainlist
db_relaydoms = pgsql;.... domainlist db_backlisted
= pgsql;....
We use the above referenced domainlists extensively throughout the
Exim mail routing and ACL's, etc.
The question is, does Exim execute the SQL query each and every time
the domainlist is referenced/used? If so, if you have about 20
routers, etc... that seems like an excessive amount; especially if
the domainlist isn't expected to change much for a single email
transaction.
If this is the case, is there any recommendations other than not
using SQL for domainlists and other data that may be pulled and
referenced via the whole mail routing/acceptance process?
ISTR that anything of a 'hostlist' or 'domainlist' structure is cached,
regardless of from whence derived. But I've been wrong before..
In any case .. though I've used PostgreSQL extensively within Exim, I do
not use it for either of those, partly 'coz in my case those are very
slow-changing - if not static - lists.
For those that do change more often, I use an lsearch, wildlsearch, or
ipsearch against a simple flat file.
Flat-file can, of course, be one that is generated and published BY an
SQL critter, and updated as often as a 'trigger' or stored procedure
decides.
That way, Exim won't stop transferring mail if the SQL engine goes hors
d' combat for a time. Just soldiers-on with the most-recent file it was
given.
Pretty sure the overall resource load is lessened as well, but have
never actually measured it accurately.
Bill
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