Emmanuel, thanks a lot for your valuable time. That clarifies things :)
However, concerning the full SQL parser. I am not sure here. Maybe the user could provide a set of (prepared) SQL statements containning the partitioned tables that he wants Sequoia to route to different DBs. Now Sequoia could easily read the parameters (keys) from those statements and decide which DB should be accessed using a simple mapping file. Now distributed joins needed when each DB contains a full set of data. What do you think? Oliver 2007/3/23, Emmanuel Cecchet <[EMAIL PROTECTED]>:
Oliver, > Referring to the MySQL docs you were pointing me to: The way I > understood MySQL partitioning, there is *no* support for vertical > partitioning. MySQL partitioning will allow you to distribute a single table over multiple nodes. However, it will not route queries to different tables on different nodes. > And: I was supposing that you would need distributed joins with > Sequoia even now. In case one table is in DB1 and another in DB2 and > you want both in a query. Isn't that so? Yes, but this is not supported as it is mentioned in the limitation section of the doc. There was a prototype designed some time ago on top of C-JDBC, not ported yet on Sequoia. But this comes at the expense of processing queries at the middleware level which brings a significant overhead. > And: Don't you need an SQL parser in any case? How do you find out > which tables are involved in a query without one? You need a parser but you don't need a full parser. Just extracting table names can be done with a minimal parser made of regular expressions. If you need to interpret the full SQL it becomes another story, and the parsing overhead might become much larger. Hope this clarifies things, Emmanuel -- Emmanuel Cecchet Chief Scientific Officer, 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 _______________________________________________ Sequoia mailing list [email protected] https://forge.continuent.org/mailman/listinfo/sequoia
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