]
Steven Hawkins commented on TEIID-5682:
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With cardinalities set this issue is somewhat mitigated as the join will be planned as a
dependent join. The rationale for raising the aggregation is if the cardinalties
aren't set and the join can be pushed. The grouping and order by operations can then
be combined.
Raise aggregation to allow for join pushdown
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Key: TEIID-5682
URL:
https://issues.jboss.org/browse/TEIID-5682
Project: Teiid
Issue Type: Enhancement
Components: Query Engine
Reporter: Steven Hawkins
Assignee: Steven Hawkins
Priority: Major
Fix For: 12.2
In some plans, for example those created by odata expand see TEIID-5680, the resulting
query has the form of:
select tbl1-cols from tbl1 left outer join (select cols, aggregates ... from tbl2 group
by cols) on (some non-aggregate predicate)
If the aggregates or other intervening constructs are not able to be pushed the result
will be a federated join.
In most instances (where the tbl1 columns are sortable) it's possible to change this
to:
select tbl1-cols aggregates from tbl1 left outer join tbl1 on (...) group by tbl1-cols,
cols
which can allow the pushdown of the join to proceed.