On 2/24/2015 4:31 AM, Vivek Choudhary wrote:
Please can someone provide me information regarding the use of RawStoreDaemon
thread in Derby database.
2 main uses off the top of my head:
1) following events that result in rows being deleted from a page (like
deleted, or aborted inserts), derby will
post work to the daemon thread to be executed after the current
transaction commits. This work involves
reading the page, getting locks on rows, changing the page if it finds
deleted rows are committed, and finally
committing a separate transaction that will result eventually in writing
that page to disk and log related I/O.
2) consistency points. Derby will schedule a consistency point after a
configurable amount of log I/O has completed.
At that point it schedule work to the daemon thread to cycle through every
page in the cache and write those that
are dirty. It also writes a log record to the transaction log. Once that work is
done the system "knows" that dirty
pages associated with transactions that committed before that point in the
log have been written and that those
log records are no longer needed for system reboot recovery.
I am pretty new to derby database and was looking for some information
regarding this.
Also, since this is a daemon thread does this impact to any cpu usage during
application runtime.
yes, though most of the impact is I/O rather than cpu related.
Thanks.
Vivek Choudhary
--
email: Mike Matrigali - [email protected]
linkedin: https://www.linkedin.com/in/MikeMatrigali
available for Derby related contract projects.
