Fixes#8275 by printing the names in order so that in every message
`DETAIL: x and y are not co-located` x precedes (or is lexicographically
less than) y.
DESCRIPTION: Adds support for pushing down LEFT/RIGHT outer joins having
a reference table in the outer side and a distributed table on the inner
side (e.g., <reference table> LEFT JOIN <distributed table>)
Partially addresses #6546
1) `<outer:reference>` LEFT JOIN `<inner:distributed>`
2) `<inner:distributed>` RIGHT JOIN `<outer:reference>`
Previously, for outer joins of types (1) and (2), the distributed side
was computed recursively. This was necessary because, when the inner
side of a recurring outer join is a distributed table, it is not
possible to directly distribute the join; the preserved (outer and
recurring) side may generate rows with join keys that hash to different
shards.
To implement distributed planning while maintaining consistency with
global execution semantics, this PR restricts the outer side only to
those partition key values that route to the selected shard during
distributed shard query computation. This method is employed )when the
following criteria are met: (recursive planning applied otherwise)
- The join type is (1) or (2) (lateral joins are not supported).
- The outer side is a reference table.
- The outer join qualifications include an equality condition between
the partition column of a distributed table and the recurring table.
- The join is not part of a chained join.
- The “enable_recurring_outer_join_pushdown” GUC is enabled (default is
on).
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Co-authored-by: ebruaydingol <ebruaydingol@microsoft.com>
Co-authored-by: Onur Tirtir <onurcantirtir@gmail.com>
Colm
eaydingol