On Tue, Sep 8, 2015 at 3:24 PM, Tom Smith <tomsmith1989sk@xxxxxxxxx> wrote: > On Tue, Sep 8, 2015 at 3:51 PM, Merlin Moncure <mmoncure@xxxxxxxxx> wrote: >> On Mon, Sep 7, 2015 at 12:07 AM, Tom Smith <tomsmith1989sk@xxxxxxxxx> >> > How to force query planner "dynamically" generate plan to >> > for each lateral select query as "t" changes. >> >> I think you're asking to much of the planner here. The query is >> planned first and executed second. Because of that partitioning >> generally depends on specific values, not dynamic ones, for exclusion >> to take effect. I would consider rewriting to loop and see if that >> helps. > > Almost all lateral query would be "dynamic sql" since it will vary as left > value changes. > perhaps query planner can mark it as "deferred" and during execution, > replacing the original planning with a newly generated plan. > Or we have to say lateral feature is not suitable for partitioned table. Lateral works fine with partitioned tables. The underlying problem is how constraint exclusion works; it depends on being able to examine the query without executing it and from there plan it out. There are a lot of ways to break this besides lateral. For example, suppose you have a table partitioned on id: SELECT * FROM foo WHERE id = 1; <- CE works SELECT * FROM foo JOIN bar USING (id); <- CE will not work, even if bar only has one record with id = 1 The rule that planning shall not depend on execution is very unlikely to change. merlin -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
