[
https://issues.apache.org/jira/browse/DERBY-306?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Knut Anders Hatlen reopened DERBY-306:
--------------------------------------
I think the in-memory database solves a different problem than the one
described here, so I'm reopening the issue.
There was a request for this on the user list not long ago:
http://mail-archives.apache.org/mod_mbox/db-derby-user/200907.mbox/%[email protected]%3e
If you have a write-intensive application and you care about the
consistency/recoverability of the database but accept loss of some transactions
in case of a crash, relaxed durability could increase the performance
significantly. An in-memory database is not an option in such a scenario,
because it's not persistent and its size is limited by the available memory.
One example use case:
I have an application[1] that processes a large body of documents[2] and stores
some aspects of it in a database. The indexing of the documents can be stopped
and re-started, and the application is able to read from the database how far
it got before it was aborted, and it knows how to continue from that point.
The indexing takes quite some time because of I/O wait on commit, and it's much
quicker with derby.system.durability=test. However, with
derby.system.durability=test, if there's a crash while indexing the documents,
the database is likely to be corrupted and must be recreated from scratch.
Since the application is able to read from the database how far it got, it is
OK to lose some transactions, as the application thinks that it didn't perform
them in the first place and will happily continue from the point of the latest
persisted transaction and redo the lost transactions.
If we had a crash-safe variant of derby.system.durability, this process would
be much faster, but an in-memory database couldn't be used because of lack of
persistence and because the database is too big to store in memory.
[1] The application is OpenGrok
(http://www.opensolaris.org/os/project/opengrok/)
[2] The body of documents is the source code for all the projects indexed at
http://src.opensolaris.org/source/
> Add relaxed durability that would ensure consistency and recoverability of
> the database
> ----------------------------------------------------------------------------------------
>
> Key: DERBY-306
> URL: https://issues.apache.org/jira/browse/DERBY-306
> Project: Derby
> Issue Type: Improvement
> Components: Store
> Affects Versions: 10.1.1.0
> Reporter: Sunitha Kambhampati
>
> Add a relaxed durability option that would ensure that the database is
> consistent and would recover. Use the property derby.system.durability to
> support this option.
> Some discussions earlier on the list, follow the thread given by this link)
> http://mail-archives.apache.org/mod_mbox/db-derby-dev/200504.mbox/%[email protected]%3e
> Also see Derby-218.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
