Patch to integrate dhcpd 4.2.0 with SQL / libdbi (mysql, postgres etc.)

Alex Bligh alex at
Thu Dec 2 23:01:37 UTC 2010


--On 2 December 2010 17:12:04 -0500 Jason Antman <jantman at> 

> We just moved from the Masney et. al. LDAP patch to static config files
> generated by PHP (from a MySQL database) mainly due to performance
> issues with LDAP. Do you have any idea how dhcpd with your patch
> compares to dhcpd with static configuration files in terms of performance?

Currently you will generate a MySQL query for every host lookup (i.e.
there is no caching in dhcpd, which is something I think should be
added). If you run MySQL locally, have hosts numbered at maximum
in the tens of thousands, and have proper indexing on the tables,
the latency added should be in the milliseconds, and you should be
able to handle hundreds of queries per second (other dhcpd constraints
aside). You can use conventional DB techniques to mirror a remote MySQL
database locally. Obviously it will never be as fast as static files,
but you will avoid the problem of your static config files being
out of date, and parsing delay rereading static files.

All that said, please read the bit on the blog post about this being
pretty early code. I don't yet have a huge amount of test data beyond
"it works in our lab" (and we're using Postgres there, though I developed
it against MySQL). All data welcomed.

Alex Bligh

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