On Tue, 2008-07-08 at 17:51 +0300, Heikki Linnakangas wrote: > Simon Riggs wrote: > > The notes say "Heikki doesn't think this is a long term solution", but > > in the following discussion it was the *only* way of doing this that > > will work with non-PostgreSQL databases. So it seems like the way we > > would want to go, yes? > > How did you come to the conclusion that this is the only way that will > work with non-PostgreSQL databases?
SQL, in text form, is the interface to other databases. You can't pass half a plan tree to Oracle, especially not a PostgreSQL plan tree. It has to be text if you wish to send a query to another RDBMS, or another version of PostgreSQL. > We should start moving towards a full SQL:MED solution that will > ultimately support pushing down joins, aggregates etc. to the remote > database. Including support for transaction control, using 2PC, and > cost estimation and intelligent planning. > > This should be done in an extensible way, so that people can write > their own plugins to connect to different RDBMSs, as well as simple > data sources like flat files. The plugin needs to be able to control > which parts of a plan tree can be pushed down to the remote source, > estimate the cost of remote execution, and map remote data types to > local ones. And it then needs to be able to construct and execute the > remote parts of a plan. So if I understand you, you want to pass the partial plan tree and then have a plugin construct the SQL text. Sounds like a great approach. Maybe you thought I meant internal interfaces should be in text? No, that would be bizarre. I meant we should not attempt to pass partial plan trees outside of the database, since that would limit the feature to only working with the same version of PostgreSQL database. I support your wish to have something that can work with other types of database. -- Simon Riggs www.2ndQuadrant.com PostgreSQL Training, Services and Support -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
