Hubert Zhang created HAWQ-850:
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Summary: Planner supports refineCachedPlan interface.
Key: HAWQ-850
URL: https://issues.apache.org/jira/browse/HAWQ-850
Project: Apache HAWQ
Issue Type: Improvement
Components: Core
Reporter: Hubert Zhang
Assignee: Lei Chang
in PBE(prepare bind execution) cases, plan will be cached, and only be
generated once in postgres.
But in HAWQ since resource is dynamic or elastic, the plan maybe changed during
the different execution of PBE. Also, the file split allocation result which is
stored in plan is dynamically too, so the split-vseg mapping may also be
changed.
For example, We call a plpgsql function which do "insert into t select * from
t".
in Prepare we cache the plan, with fixed split-vseg mapping(e.g. 10 blocks),
but after insert, there would be 20 blocks so the old split-vseg mapping is
invalid. We need to update it. Also when we call this function again and again,
the data size of t may request more resource to handle it than the first call,
so we should recalculate the entire plan with the new vseg number.
This function is implemented in a interface called refineCachedPlan.
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