Aleksey Plekhanov created IGNITE-27489:
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Summary: Calcite engine. Merge projects into join
Key: IGNITE-27489
URL: https://issues.apache.org/jira/browse/IGNITE-27489
Project: Ignite
Issue Type: Improvement
Reporter: Aleksey Plekhanov
Assignee: Aleksey Plekhanov
It's an common case when project rel node is placed on top of join node, since
almost always we skip some columns from join inputs. For example, for join like:
{code:java}
SELECT ... FROM emp JOIN dept ON emp.deptno = dept.deptno
{code}
Only one {{deptno}} column is enough for user.
Join constructs row as concatination of both left and right hand, and project
rel node construct yet another row. We can optimize such an approach, merge
project node into join node and construct only one row based on two inputs. We
using the same approach for filtering (see ExpressionFactoryImpl#biPredicate)
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