Details
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New Feature
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Status: Open (View Workflow)
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Major
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Resolution: Unresolved
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6.1.1
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None
Description
As of 6.1.1 TupleBPS::sendJobs() sends out JobList.MaxOutstandingRequests(20 extents of work by default) * 1024 Primitive Jobs simultaneously. By default it worths 20 extents of columnar data.
In case of queries like SELECT * FROM table_with_500_columns LIMIT 1 this overwhelms PPs with needless work and spoils the buffer cache. The optimizer must propagate the LIMIT into TupleBPS so that it issues a limited number of outstanding Primitive jobs for queries where it is semantically possible.