Hash or btree for access.db

Ok, I've done some searching and can't find any definitive answer as
to which is best. The only differences I can see on my (old slow)
system is that makemap hash takes over 5 minutes to run and makemap
btree takes just a little over 1 minute. (My access text file has 
about 100000 lines). Am I taking a performance hit with sendmail if
I use the btree rather than hash? I've tried it both ways and can't 
really see any difference other than the time it takes to rebuild the
database.

-ray

Btree is better for building BIG dtabases from "key sorted" input files.

Using big access db is not recomended. Sendmail can do 20-30 access 
lookups per one incoming message. When big part of access.db file is not 
cached by library itself or file system cache it may create big 
penalties approaching one disk I/O operation per one lookup.

-- 
Andrzej [en:Andrew] Adam Filip  XXXX@XXXXX.COM   XXXX@XXXXX.COM 
"All that is necessary for the triumph of evil is that good men do
  nothing"  -- Edmund Burke (18th century)

In article <d8oguj$541$ XXXX@XXXXX.COM >,




But how big is big? Is 100000 or so entries considered big? And for
what it's worth, my input files are (mostly) sorted.


Once again though, how big is big?  My access.db is around 16 Mb (it is
about 30% larger using hash instead of btree). I haven't seen any
performance differences, but the system isn't particularly busy either.
There are only a few real users and message traffic is in the thousands
per day. It's a PII 266 with 128 Mb of ram and load average tends to run 
around .05 or less most of the time. 

-ray

It depends on memory size (size of in memory file system cache).
IMHO 1E5 is not a big db for relatively modern PC server.

Building btree from sorted (or partially sorted) input file reduces 
number of required disk I/O operations when created db is not fully 
cached by system cache of file system.


Can you report the following:
1) (peak) physical ram usage [size of free/available physical memory]
2) number of messages received in the busiest hour of week
3) use of AS/AV software (scanning message bodies "in smtp session")

Use some software to track memory usage, system (CPU) load and disk I/O 
operations (It is OS/distribution dependent) - it should provide you 
more reliable indicators.

-- 
Andrzej [en:Andrew] Adam Filip  XXXX@XXXXX.COM   XXXX@XXXXX.COM 
"All that is necessary for the triumph of evil is that good men do
  nothing"  -- Edmund Burke (18th century)