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  1. HPCC
  2. HPCC-12589

Optimize JOINs used to filter records

    Details

    • Type: Improvement
    • Status: Resolved
    • Priority: Minor
    • Resolution: Timed Out
    • Affects Version/s: None
    • Fix Version/s: None
    • Component/s: Code Generator
    • Labels:

      Description

      If you have

      JOIN(dataset, other, <cond>, TRANSFORM(LEFT), KEEP(1), INNER)

      Then the join is effectively being used to filter the record set. It will often be better to migrate the join up through dataset (in the same way that a filter condition is). Possibly especially if it is a lookup join [be careful if it is local!]

      Good candidates would be moving over sorts and distributes - it would be worth investigating what examples occur in real world queries.

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            • Assignee:
              anybody Available for anyone
              Reporter:
              ghalliday Gavin Halliday
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