LakshSingla opened a new pull request, #13952:
URL: https://github.com/apache/druid/pull/13952
### Description
Currently, in the ClientQuerySegmentWalker, when the data sources get
inlined, they can be limited by the number of rows to prevent a query
(subquery) from hogging up the broker's memory. This however doesn't have a
proper correspondence with the memory used, since a row can have multiple
columns with varying amounts of data in them. Therefore it would be better if
there is a memory limit also available, which prevents the subquery's results
from exploding beyond a certain memory limit.
This PR aims to use the Frame which were introduced along with the MSQ to
store the inline results. Since the Frames are backed by memory, we can fetch
the memory used by the frame, and correspondingly the data source to estimate
the size that is consumed by the inline data source. This is a close estimate
of the size taken by the subquery results.
##### Limitations
Currently, if the row signatures contain columns with unknown types, then
this falls back to the rows for generating the intermediate result.
#### Release note
To be added
<hr>
##### Key changed/added classes in this PR
<hr>
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- [ ] added integration tests.
- [x] been tested in a test Druid cluster.
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