Hi John,
I spent most of the day getting sequoia setup and configured, and now
I’m not even sure if it does what I need it to. I have two different
databases that I need to combine into one source for some reporting.
The reports have to match rows from the two sources, having them in
one central location would be so much easier to work with.
I created a virtual database with 2 backends, one for each different
data source. They both go in and are enabled, but when I run show
tables; , I only see tables from the first database backend. Is that
what is supposed to happen or is it a misconfiguration? I need it to
show me all of the tables from both databases. So my basic question
is, can sequoia combine different databases like this or is it only
for clustering databases that are identical?
If you use RAIDb-0, you can aggregate multiple datasources but Sequoia
does not handle distributed joins. Therefore it will only act as a
router not as a distributed database engine.
In practice, it means that if node1 has table t1 and node2 has table t2,
if you execute 'SELECT * FROM t1' the query will be routed to node1. If
you try 'SELECT * FROM t1,t2 WHERE ...', Sequoia will return an error
and tell you that there is no node that has both tables t1 and t2.
<RequestManager caseSensitiveParsing="false" beginTimeout="60"
commitTimeout="60" rollbackTimeout="60">
...
<LoadBalancer transactionIsolation="databaseDefault">
<RAIDb-1>
It is surprising that you did not get an error at enable time if your
databases have different schemas. Do you have different table names on
your 2 nodes ?
Thanks for your feedback,
Emmanuel
--
Emmanuel Cecchet
Chief Architect, Continuent
Blog: http://emanux.blogspot.com/
Open source: http://www.continuent.org
Corporate: http://www.continuent.com
Skype: emmanuel_cecchet
Cell: +33 687 342 685
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