[
https://issues.apache.org/jira/browse/CALCITE-1234?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15279812#comment-15279812
]
Jesus Camacho Rodriguez commented on CALCITE-1234:
--------------------------------------------------
Also this one by the guys at TU Berlin:
Opening the Black Boxes in Data Flow Optimization
http://stratosphere.eu/assets/papers/openingTheBlackBoxes_12.pdf
In the context of their Stratosphere project (MR + additional primitives), they
define a set of properties that when known are sufficient to reorder operators
even when we do not know their semantics.
> Annotate table functions to allow pushing down project, filter
> --------------------------------------------------------------
>
> Key: CALCITE-1234
> URL: https://issues.apache.org/jira/browse/CALCITE-1234
> Project: Calcite
> Issue Type: Bug
> Reporter: Julian Hyde
> Assignee: Julian Hyde
>
> In general it is not possible to push relational operators through table
> functions but many table functions have properties that will allow push down:
> for instance, they might preserve fields, preserve row count, return rows in
> the same order. If we annotate a table function with these properties, we can
> automatically push down a Filter, and so forth.
> Some ideas:
> * {{PreservesFieldNames}}: If an output field has the same name as an input
> field, it is assumed to be the same field.
> * {{PreservesRows}}: Each input row causes exactly one output row, in the
> same order.
> * {{FiltersRows}}: Each input row causes at most one output row, in the same
> order.
> * {{PreservesFieldPositions}}: The leading N columns of the output are
> equivalent to the leading N columns of the input.
> If {{(PreservesFieldNames or PreservesFieldPositions) and (PreservesRows or
> FiltersRows)}}, it is safe to push down a Filter if all of the fields of the
> predicate exist in the input.
> Similarly pushing down a Project; and we can push down an Aggregate if
> {{PreservesRows}}.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
