On Sat, May 09, 2009 at 10:20:02AM -0600, LuKreme wrote:
> On 8-May-2009, at 10:31, Wietse Venema wrote:
>> Short reply: s/mysql/proxy:mysql/
>
> Is there any reason to *NOT* do this? I mean, should you use proxy: every
> time you use a mysql lookup?
Sophisticated users who know which tables are used by which services
may avoid "proxy:" with tables used *only* in trivial-rewrite, as the
indirection adds no value, just slightly raises latency.
The main benefit of proxymap is with tables used by high-concurrency
processes, such as smtpd(8), cleanup(8) and smtp(8).
- access(5) tables used in smtpd(8)
- canonical(5), virtual(5), ... tables used in smtpd(8) and cleanup(8)
- generic(5) tables used in smtp(8) (aka lmtp(8))
Most other Postfix services don't interact with outside systems, and
typically run at low concurrency (low latency, low demand or both).
Privileged services avoid "proxymap" for security reasons:
# ====================================================================
# service type private unpriv chroot wakeup maxproc command + args
# (yes) (yes) (yes) (never) (100)
# ====================================================================
local unix - n n - - local
virtual unix - n n - - virtual
This means that "proxy:" is ignored with:
- aliases(5) in local(8)
- $virtual_mailbox_maps in virtual(8)
However, both are usually also consulted by smtpd(8) when doing recipient
validation, so you should have "proxy:" in these, as it is ignored when
not applicable and very useful otherwise.
Finally, "proxy:" is also ignored with:
- mailbox_command_maps
- virtual_uid_maps
- virtual_gid_maps
with these, it makes no difference wether you add a "proxy:" prefix
or not, regardless, the table will be accessed directly.
--
Viktor.
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