Joe Uhl wrote:
This seems like a pretty major weakness in PostgreSQL partitioning. I
have essentially settled on not being able to do queries against the
parent table when I want to order the results. Going to have to use a
Hibernate interceptor or something similar to rewrite the statements so
they hit specific partitions, will be working on this in the coming week.
This weakness is a bummer though as it makes partitions a lot less
useful. Having to hit specific child tables by name isn't much
different than just creating separate tables and not using partitions at
all.
I wonder if the "offset 0" trick would work here? I was told (for a different question) that the planner can't merge levels if there's an offset or limit on a subquery. So you might be able to do something like this:
select ... from (select ... offset 0) as foo order by ...
In other words, put your primary query as a sub-select without the sort criterion, with the "offset 0" as a sort of roadblock that the planner can't get past. Then the outer select does the sorting, without affecting the plan for the inner select.
Craig
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