LakshSingla opened a new pull request, #16619:
URL: https://github.com/apache/druid/pull/16619
### Description
The query engine is unable to estimate the correct size in bytes of the
subquery results when the scan query has columns which are missing from the
segments. This is because the ScanQueryEngine receives all the columns of the
scan query, and populates the row signature with null type if its unable to
find the column in the segment.
This PR modifies the materializing logic to materialize the results of the
columns whose types are known, and check that the columns whose types are
unknown always have `null` values. This is helpful because:
a. If the type is unknown and the column contains all null values, we don't
need to materialize the results
b. If the type is unknown and the column contains non-null values in any
row, we are running into the case of missing types, and we should throw an
error.
#### Release note
Fixes a bug causing maxSubqueryBytes to not work when segments have missing
columns.
<hr>
##### Key changed/added classes in this PR
* `MyFoo`
* `OurBar`
* `TheirBaz`
<hr>
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- [ ] added integration tests.
- [ ] been tested in a test Druid cluster.
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