Re: [HACKERS] Runtime Partition Pruning

On 14 April 2018 at 05:04, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> But I wonder why it's the executor's job to clean up after the
> planner, instead of adjusting the relevant planner functions to avoid
> leaking memory?

It might be possible, but it might also be risky and difficult.

For a while, during my review of the faster partition pruning patch I
was asking Amit to add pfree() calls in various places for this exact
reason, but in the end, I gave up and decided it was easier to just
create a new memory context to call the planner function from. I've
now forgotten the exact reason why I finally decided it was too much
trouble. The pruning code now works using your step logic so perhaps
that reason no longer applies, although, on a quick scan of the
pruning code now, it seems to require that get_matching_partitions
performs a deep pfree of each PruneStepResult. However, there is still
partkey_datum_from_expr which performs ExecInitExpr, although perhaps
that can just be done once, and the result stashed in the
PartitionPruneContext.

--
David Rowley http://www.2ndQuadrant.com/
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