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tem 1st September 2009 05:22

how to calculate cache size for LDAP DB
 
Hi All,
Im tuning my LDAP DB (BDB type).
Im reading at http://www.openldap.org/doc/admin24/...y%20DB%20Cache

Quote:

#(Number of hash buckets + number of overflow pages + number of duplicate pages) * page size / 2
#The objectClass index for my example database is 5.9MB and uses 3 hash buckets and 656 duplicate pages. So:
# ( 3 + 656 ) * 4KB / 2 =~ 1.3MB.
#With only this index enabled, I'd figure at least a 4MB cache for this backend. (Of course you're using a single cache shared among all of the database files, so the cache pages will most likely #get used for something other than what you accounted for, but this gives you a fighting chance.)
I understand that: with each index ( in this case only objectclass is indexed), we must calculate their cache size individually and sum every them. (1)
- I can specify Number of hash buckets & Cache Size (2)by command
Quote:

Shell> db_stat-4.4 -m | head -n 25
32771 Number of hash buckets used for page location
Pool file: <index>.bdb
<number> page size
- I can specify Number of overflow pages & Number of duplicate pages by command
Quote:

Shell> db_stat-4.4 -d *.bdb (3)
0 Number of tree duplicate page
0 Number of tree overflow pages
(1) Did I understand right?
(2) Which page size will we use, some of index file use 4K page size, others use 16K page size?
(3) Do must I run for each index or *.bdb is still ok?

Could anyone help me? This chapter is not clearly huh?

Thank for reading


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