On 12/16/2014 05:52 PM, Robert Haas wrote: > But in a more complicated case where the value there isn't known until > runtime, yeah, it scans everything. I'm not sure what the best way to > fix that is. If the partition bounds were stored in a structured way, > as we've been discussing, then the Append or Merge Append node could, > when initialized, check which partition the id = X qual routes to and > ignore the rest. But that's more iffy with the current > representation, I think.
Huh. I was just testing: WHERE event_time BETWEEN timestamptz '2014-12-01' and ( timestamptz '2014-12-01' + interval '1 month') In that case, the expression above got folded to constants by the time Postgres did the index scans, but it scanned all partitions. So somehow (timestamptz + interval) doesn't get constant-folded until after planning, at least not on 9.3. And of course this leaves out common patterns like "now() - interval '30 days'" or "to_timestamp('20141201','YYYYMMDD')" Anyway, what I'm saying is that I personally regard the inability to handle even moderately complex expressions a major failing of our existing partitioning scheme (possibly its worst single failing), and I would regard any new partitioning feature which didn't address that issue as suspect. -- Josh Berkus PostgreSQL Experts Inc. http://pgexperts.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers