On Mon, 2009-11-23 at 18:31 -0500, Greg Smith wrote: > Robert Haas wrote: > > I'm fuzzy on what problem this is attempting to solve... as mentioned > > in the above guidelines, it's usually good to start with some design > > discussions before writing/submitting code. > This has been through some heavy design discussions with a few PG > hackers you know and some you don't, they just couldn't release the > result until now. As for what it's good for, if you look at what you > can do now with dblink, you can easily move rows between nodes using > dblink_build_sql_insert. This is perfectly fine for small bits of work, > but the performance isn't nearly good enough to do serious replication > with it. The upper level patch here allows using COPY as the mechanism > to move things between them, which is much faster for some use cases > (which includes most of the really useful ones). It dramatically > increases the scale of what you can move around using dblink as the > replication transport. > > The lower level patch is needed to build that layer, which is an > immediate proof of its utility. In addition, adding a user-defined > function as a COPY target opens up all sorts of possibilities for things > like efficient ETL implementation. And if this approach is accepted as > a reasonable one, as Dan suggested a next step might even be to > similarly allow passing COPY FROM through a UDF, which has the potential > to provide a new efficient implementation path for some of the custom > input filter requests that pop up here periodically.
Can this easily be extended to do things like COPY stdin TO udf(); or COPY udf() FROM stdin; so that I could write a simple partitioning function, either local for partitioned tables or using pl/proxy for partitioned databases ? > -- > Greg Smith 2ndQuadrant Baltimore, MD > PostgreSQL Training, Services and Support > g...@2ndquadrant.com www.2ndQuadrant.com > > -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
