Fix OLAP window function SQL generation when preceded by groupBy with computed expressions

[peledni]

Summary

• Fixes invalid SQL generation when using groupBy with computed expressions (e.g., monthNumber(), year()) followed by olapGroupBy
• The PARTITION BY clause was referencing raw expressions instead of column aliases, causing "Column must be in GROUP BY list" errors
• Extended subselect isolation logic to wrap GROUP BY queries when followed by window functions

Problem

When using groupBy with computed expressions followed by olapGroupBy, the generated SQL was invalid:

Trade.all()
   ->project([col(t|$t.date->monthNumber(), 'month'), col(t|$t.quantity, 'quantity')])
   ->groupBy(['month'], agg('totalQty', x|$x.getFloat('quantity'), y|$y->sum()))
   ->olapGroupBy(['month'], func('totalQty', y|$y->count()), 'monthCount')

Before (invalid SQL):

SELECT extract(month from "root".tradeDate) as "month", sum("root".quantity) as "totalQty", 
       count(sum("root".quantity)) over (partition by extract(month from "root".tradeDate)) as "monthCount" 
FROM tradeTable as "root" 
GROUP BY "month"

After (valid SQL):

SELECT "subselect"."month" as "month", "subselect"."totalQty" as "totalQty", 
       count("subselect"."totalQty") over (partition by "subselect"."month") as "monthCount" 
FROM (SELECT extract(month from "root".tradeDate) as "month", sum("root".quantity) as "totalQty" 
      FROM tradeTable as "root" GROUP BY "month") as "subselect"

Test plan

• Added new test case testGroupByWithComputedExpressionFollowedByOlapGroupBy
• Updated existing test testExecutionPlanGeneration to reflect new expected SQL structure
• Verified SQL generation produces valid syntax for PostgreSQL and H2

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: peledni / name: Nir Peled (0022ca3)

[github-actions]

Test Results

  1 057 files   -      18    1 057 suites   - 18   2h 54m 53s ⏱️ - 1h 0m 27s
13 592 tests  -      80  13 423 ✔️  -      80  169 💤 ±0  0 ❌ ±0 
29 994 runs   - 2 727  29 825 ✔️  - 2 727  169 💤 ±0  0 ❌ ±0 

Results for commit 0022ca3. ± Comparison against base commit 4955997.

♻️ This comment has been updated with latest results.

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[finos-admin]

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