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Design/Recovery Questions on Two-Phase Commit (2PC) Protocol

From: Lee <leereilly_at_gmail.com>
Date: 25 Aug 2005 14:21:44 -0700
Message-ID: <1125004904.933286.287260@g14g2000cwa.googlegroups.com>


Hi there,

I have a few questions about the two-phase commit protocol in action - specifically, design help/pointers for how to respond to failure. If you have any URLs with relevant design/technical help, they'd also be appreciated...

We're building an application that will run at three different sites (A, B, and C). Each site will have its own Oracle installation, and each site's database will be responsible for working with two schemas.

	Site A: Works with schemas 1 and 2.
	Site B: Works with schemas 3 and 4.
	Site C: Works with schemas 5 and 6.

Note that each Oracle installation will actually hold all six schemas, and in perfect operation, all six schemas should contain identical data.

Good scenario:
Site A processes some data, updates schemas 1 and 2 both locally and remotely. 2PC ensures that changes are made across all sites.

Bad scenario 1:
Site A processes some data, updates schemas 1 and 2 both locally and remotely, but has to rollback as the database is down at REMOTE site 3. How would you respond to this?

Bad scenario 2: Site A processes some data, updates schemas 1 and 2 both locally and remotely, but has to rollback as the database is down at the LOCAL database. How would you respond to this?

My solution would be something along the lines of the following (note the lack of implementation details)... re-try X times, and then flag the database as being DOWN. All sites now ignore this database, and the site with the failed database now uses one of the remote database. Later, somehow, the databases are re-synched (hopefully without bring them down).

I'm actually a java developer being tasked with taking on some DB design/admin duties, so please take it easy on me. Any help, URLs, or literature recommendations greatly appreciated!

Received on Thu Aug 25 2005 - 16:21:44 CDT

Original text of this message

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