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  1. Derby
  2. DERBY-6921 How good is the Derby Query Optimizer, really
  3. DERBY-6954

Allow plans to execute where HASH tables are estimated to spill to disk.

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    • Sub-task
    • Status: Open
    • Major
    • Resolution: Unresolved
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    • SQL
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    Description

      Derby Optimizer currently rejects the plans where it estimates that intermediate HASH Tables in HASH Joins will spill to disk. We need to model the cost associated of HASH Join disk spill in order to make them a candidate for optimal plan. DERBY-6938, DERBY-1259 and DERBY-106 contain some useful details around this behaviour.

      One possible workaround around this behaviour is to explicitly specify optimizer hints and overriding the default optimizer behaviour.
      https://db.apache.org/derby/docs/10.13/tuning/ctunoptimzoverride.html

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            harshvardhan145 Harshvardhan Gupta
            harshvardhan145 Harshvardhan Gupta

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