The filter doc contains the following language:
Commonly, the file name specified for *once* is used as the base name
for direct-access (DBM) file operations. There are a number of
different DBM libraries in existence. Some operating systems provide
one as a default, but even in this case a different one may have
been used when building Exim. With some DBM libraries, specifying
once results in two files being created, with the suffixes .dir and
.pag being added to the given name. With some others a single file
with the suffix .db is used, or the name is used unchanged.
Using a DBM file for implementing the *once* feature means that the
file grows as large as necessary. This is not usually a problem, but
some system administrators want to put a limit on it. The facility
can be configured not to use a DBM file, but instead, to use a
regular file with a maximum size. The data in such a file is
searched sequentially, and if the file fills up, the oldest entry is
deleted to make way for a new one. This means that some
correspondents may receive a second copy of the message after an
unpredictable interval. Consult your local information to see if
your system is configured this way.
It is not clear to me what "local information" I should consult.
I installed exim for source and the main lookup format (used for
retry hints etc.) is the default for linux, ie. -ldb . Does that
mean this will be always used for the once database? Under what
circumstances is the flat file format used?
--
Ian
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