Greg, > Well Oracle has lots of partitioning intelligence pushed up to the planner > to avoid overhead. > > If you have a query with something like "WHERE date = '2004-01-01'" and > date is your partition key (even if it's a range) then Oracle will figure > out which partition it will need at planning time.
Hmmm ... well, we're looking at making a spec for Postgres Table Partitioning. Maybe you could help? > But I'm a bit puzzled. Why would Append have any significant cost? It's > just taking the tuples from one plan node and returning them until they run > out, then taking the tuples from another plan node. It should have no i/o > cost and hardly any cpu cost. Where is the time going? Beats me. Tom? > In my experience "global indexes" defeat the whole purpose of having the > partitions. They make dropping and adding partitions expensive which was > always the reason we wanted to partition something anyways. Hmmm. Possibly, I was just thinking about the cost to partitioned tables when you do a selection *not* on the partitioned axis. Also that currently we can't enforce UNIQUE constraints across partitions. But maybe reducing the cost of Append is the answer to this. > It is handy having a higher level interface to deal with partitioned > tables. You can create a single "local" or "segmented" index and not have > to manually deal with all the partitions as separate tables. But that's > just syntactic sugar. Right, and the easy part. -- Josh Berkus Aglio Database Solutions San Francisco ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster
