Rob Vesse created JENA-681:
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Summary: Allow the old less aggressive filter placement behaviour
to be optionally used in place of the newer more aggressive behaviour
Key: JENA-681
URL: https://issues.apache.org/jira/browse/JENA-681
Project: Apache Jena
Issue Type: Improvement
Components: ARQ, Optimizer
Affects Versions: Jena 2.11.1
Reporter: Rob Vesse
Assignee: Rob Vesse
Fix For: Jena 2.11.2
In investigating some optimiser caused performance regression issues that
occurred after we upgraded at Cray to using 2.11.1 it was discovered that the
new filter pushing was too aggressive for our backend in how it broke up
BGPs/quadpatterns
Ideally we would like to use the filter placement mode where we place filters
without breaking BGPs but as discussed in JENA-627 and JENA-628 (as well as
other related issues) this behaviour is broken in the 2.11.1 release and indeed
the specific problem query did get horribly mangled with this mode enabled.
I have been able to verify that the relevant fixes for those bugs means the
affected query does now get optimised appropriately using the latest trunk code
and I've added a sanitised version of the relevant query to the test cases.
*However* it would be nice if we had the option of switching back on the more
conservative pre 2.11.1 filter placement behaviour if we desired. This is
preserved in {{TransformFilterPlacement_Old}} and currently noted in comments
that it will be removed in future.
What I propose to do instead is to rename this to
{{TransformFilterPlacementConservative}} and add an associated
{{optFilterPlacementConservative}} flag which when explicitly enabled will use
the old filter placement behaviour rather than the newer more aggressive filter
placement behaviour.
I'll attach a proposed patch for this later today
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