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Re: allow DEFAULT_DB_PAGE_SIZE to be set (ITS#483)


On Mon, 20 Mar 2000, Randy Kunkee wrote:

> I tried 16384 (the maximum the docs say this can be).

>From db_intro(3):

       DB  stores  database  file page numbers as unsigned 32-bit
       numbers and database file page sizes  as  unsigned  16-bit
       numbers.  This results in a maximum database size of 2^48.
       The minimum database page size is 512 bytes, resulting  in
       a minimum maximum database size of 2^41.

       DB  is potentially further limited if the host system does
       not have filesystem support for files  larger  than  2^32,
       including seeking to absolute offsets within such files.

       The maximum btree depth is 255.

This means the maximum page size should be 65536.

> > > On the other hand, I loaded a rather large (~300MB id2entry.dbb) into the
> > > new version via ldif this weekend, and was not able to find anything on
> > > the new one.
> > 
> > Meaning that searching no longer worked?  That's odd.
> > 
> > > Platform: Alpha OSF4.0e OPENLDAP_RELENG_1_2, db-2.7.7.  Not nearly as
> > > satisfying, though the final files were a lot smaller.
> > 
> > Did you set the pagesizes larger (to 16384 or something bigger)?  I found
> > the sizes to be about 1/3 as big.  I guess the entries were larger than
> > the 1024 byte page size and caused lots of wasted space, whereas with the
> > 16384, all data for the entry fits into a page.
> > 
> > Can't say I'ved tried it on an OSF machine, though.

Don Badrak <dbadrak@census.gov>              301.457.8263 work
Telecommunications Office                    301.457.4438 fax
U.S. Bureau of the Census
Suitland MD, USA