| > They beat up Rdb badly saying something about the way we use record
> clustering was dangerous.
Any more details? The only issue that I have heard raised is that it is
not explicit and that it has restrictions. The argument goes that
there should be syntax to cluster records and not a reliance upon
'coincedence' by using common indexes and mixed page formats in a database
area. The restriction argument is really a request for improvement. It
would be more powerful to cluster records without requiring them to share
a common primary key.
Changing an index or not setting up the storage area correctly could
lead to a non or poor use of clustering. This could have serious
performance implications. A little experience and use of RMU/Analyze
can solve this problem.
> Later, after we beat them at a Benchmark they reported decided to
> incoporate it into NonStopSQL.
Clearly, we have a good implementation.
> What exactly are they talking about?
We need more information from Tandem.
> Also, I was under the impression that NS-SQL implemented two phase
> commit, now I here that TRUE TPC will be released next summer.
One possibility is that the current Tandem approach is to
support homogeneous, integrated (I am sure these aren't the correct words)
distributed databases. With this model they can distribute the database
over a Tandem cluster where the database is explicitly aware of the different
nodes in the cluster. If one node dies, part of the database is not
accessible. You can not treat part of the distributed
database as a separate database. Because the distributed database is
one physical database, 2 PC is not required.
Compare this model to the federated distributed database. In this model,
a logical, distributed database comprises multiple physical databases.
Each physical database has its own security schema and can be accessed
autonomously. That is, each physical database is an autonomous, separate
database.
In order to coordinate an update across multiple physical databases you
need 2 PC.
Another way of looking at this is: How many log files does Tandem currently
require for a 16-node distributed database?
A federated distributed database will require one (two if mirrored) for each
physical database and one for the distributed transaction manager (the
distributed database).
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