Re: commit: ldap/doc/man/man5 slapd-bdb.5

[Hallvard B Furuseth <h.b.furuseth@usit.uio.no>]

Howard Chu writes:
> The default in slapd is an explicit 4KB.

Duh, the patch I was replying to said that...

BTW, if back-bdb and dbpagesize measure pages in 1K block units,
back-bdb must ensure Berkeley DB doesn't pick 512-byte blocks.

> I agree that defaulting to the underlying FS block size might be
> better,

Actually that's stronger that I suggested.  It's been a while
since I read the tuning guides, but I thought it was a trade-off
for what one cares most about.  Performance, integrity, space.
Maybe whether a database has many index keys with large ID lists.


Brainstorming a bit more: For a DB admin, I imagine it could be
nice to allow "I don't care as long as you don't pick too small or
too large pages".  I.e. a pagesize range:
    dbpagesize [ * | file ] { integer | [integer]-[integer] }
"*" = all files not overridden by a "file" configuration.
pagesize = (filesys_pagesize <= range_min ? range_min :
            filesys_pagesize >= range_max ? range_max :
            filesys_pagesize);

I have no idea if that's useful enough to bother with though.  If
one tries to write a template for a "general" config, it might be
better to write a script which dynamically creates one.

-- 
Hallvard