On 12/05/2012 06:37 AM, Kohsuke Kawaguchi wrote:
H2 database, when opened, takes up about 1MB in heap.
Seems excessive when typical jobs will have much less data than this that needs
to be stored.
I am still not convinced that using a SQL database for this kind of thing is
appropriate.
1. Portability of SQL is a bit of a red herring because once you start using, say, H2 to store per-job data, you cannot casually switch to another DB without losing
historical build records; and Jenkins would have to ship with _some_ DB plugin, or all plugins using the DB API would be broken. And for per-job DBs we are narrowing the
field to those that are embeddable, which probably means just H2 in practice.
2. SQL databases are generally optimized for one slow-to-start instance, a small number of expensive connections, and maybe dozens of tables with lots of data. Whereas we
need thousands of extremely cheap instances, each with one immediately available connection and a few tables with usually not so much data. The closer we can get to
java.io.RandomAccessFile.<init> the better.
Is there any fully free (so not BDB-JE) DB which is pure Java, embeddable, supports some kind of indices, supports compact binary schemas (so not e.g. Lucene or the
current wave of JSON DBs), and has a very simple client API once the connection is set up; while being openable from one or two disk files in say under a millisecond with
no significant penalty beyond the file descriptor? MapDB [1] looks most promising so far.
[1] https://github.com/jankotek/mapdb
