[multistage] Adding Stage node support for UncollectNode

[xiangfu0]

For unnest query support in v2:

SELECT a.col1, col22 FROM a CROSS JOIN UNNEST(a.col2) AS t(col22)

• [X] Sql -> SqlNodeAndOption
• [X] SqlNodeAndOption -> StageNode (Query Plan)

Next:

1. Optimize StageNodes CorrelateNode + UncollectNode to UnnestNode for execution
2. Plan execution.

[codecov-commenter]

Codecov Report

Merging #10488 (4eecc11) into master (2d6a38c) will increase coverage by 0.02%. The diff coverage is 61.95%.

@@             Coverage Diff              @@
##             master   #10488      +/-   ##
============================================
+ Coverage     70.33%   70.35%   +0.02%     
+ Complexity     6499     6493       -6     
============================================
  Files          2108     2110       +2     
  Lines        113535   113625      +90     
  Branches      17117    17122       +5     
============================================
+ Hits          79859    79946      +87     
+ Misses        28083    28078       -5     
- Partials       5593     5601       +8     

Flag	Coverage Δ
integration1	24.33% <0.00%> (-0.17%)	:arrow_down:
integration2	24.12% <0.00%> (-0.01%)	:arrow_down:
unittests1	67.88% <61.95%> (-0.02%)	:arrow_down:
unittests2	13.87% <0.00%> (-0.02%)	:arrow_down:

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...java/org/apache/pinot/common/utils/DataSchema.java	79.41% <ø> (ø)
...e/pinot/query/planner/ExplainPlanStageVisitor.java	76.74% <0.00%> (-1.83%)	:arrow_down:
...t/query/planner/logical/ShuffleRewriteVisitor.java	0.00% <0.00%> (ø)
...hysical/colocated/GreedyShuffleRewriteVisitor.java	0.00% <0.00%> (ø)
...lanner/stage/DefaultPostOrderTraversalVisitor.java	0.00% <0.00%> (ø)
.../pinot/query/runtime/plan/PhysicalPlanVisitor.java	89.79% <0.00%> (-3.83%)	:arrow_down:
...t/query/runtime/plan/ServerRequestPlanVisitor.java	84.87% <0.00%> (-1.46%)	:arrow_down:
...pache/pinot/query/planner/stage/CorrelateNode.java	66.66% <66.66%> (ø)
...che/pinot/query/planner/logical/RexExpression.java	87.37% <75.00%> (-6.47%)	:arrow_down:
...pache/pinot/query/planner/stage/UncollectNode.java	83.33% <83.33%> (ø)
... and 3 more

... and 34 files with indirect coverage changes

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[nizarhejazi]

@xiangfu0 Would CROSS JOIN UNNEST between correlated LHS and RHS (UNNEST basically operates on a field that belongs to left join relation) results only in the cross product of the current row of the left table with all the rows from the UNNEST output?

[walterddr]

@xiangfu0 Would CROSS JOIN UNNEST between correlated LHS and RHS (UNNEST basically operates on a field that belongs to left join relation) results only in the cross product of the current row of the left table with all the rows from the UNNEST output?

that's the definition when doing

... FROM tbl CROSS JOIN UNNEST(tbl.arrCol)

see LATERAL & UNNEST in https://www.postgresql.org/docs/current/queries-table-expressions.html

[walterddr]

this PR can be closed if we have #10685 yes?

[xiangfu0]

this PR can be closed if we have #10685 yes?

I think UncollectNode is still need, CorrelateNode is not needed.

I will rebase once #10685 is merged.

[xiangfu0]

this PR can be closed if we have #10685 yes?

I think UncollectNode is still need, CorrelateNode is not needed.

I will rebase once #10685 is merged.

Decorrelate won't work on the correlate + uncollect node. I think we should handle this in a rule and write our own StageNode for translation.

[walterddr]

Decorrelate won't work on the correlate + uncollect node. I think we should handle this in a rule and write our own StageNode for translation.

hmm. this is probably expected as the unCollect is more like a UDTF (user-defined table function) that expands 1-row into n-rows. modeling it as a self-join will not simplify the plan

[xiangfu0]

For Unnest, we need to have a separated operator to work on it, it's not able to decorrelate.