kennknowles opened a new issue, #19023:
URL: https://github.com/apache/beam/issues/19023

   Currently, Beam SQL supports LIMIT in two ways:
   
   1. Within a query, the results are subject to LIMIT. This works.
   2. The shell knows to cancel a pipeline when the limit is reached, even if 
there is unfinished unbounded data.
   
   The canceling of a pipeline works via a basic pattern match against the 
query execution plan, checking a few child nodes of the BeamEnumerableConverter 
for a BeamSortRel without a collation. If it can figure out what the limit is 
for the outermost query, then it will cancel the pipeline.
   
   A more robust approach might be to use traits (or some other thorough 
analysis) to see if there is a known size for the outermost query. This would, 
for example, be unaffected by any number of layer of non-size-changing 
transformations.
   
   Imported from Jira 
[BEAM-4719](https://issues.apache.org/jira/browse/BEAM-4719). Original Jira may 
contain additional context.
   Reported by: kenn.


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