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  1. Blazegraph (by SYSTAP)
  2. BLZG-1375

CONSTRUCT implicit SELECT REDUCED should be avoided when CONSTRUCT is obviously distinct without it.

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    Details

    • Type: Bug
    • Status: Open
    • Priority: Medium
    • Resolution: Unresolved
    • Affects Version/s: None
    • Fix Version/s: None
    • Component/s: Query Plan Generator
    • Labels:
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      Description

      Per BLZG-1341, we implicitly convert a CONSTRUCT query into a SELECT query with a REDUCED projection. This results in a DISTINCT SOLUTIONS operator (JVMDistinctBindingSetsOp or the equivalent native hash index operator) being added into the query.

      This should be avoided when the WHERE clause of the query is already obviously distinct since it is redundant and only wastes space.

      See https://jira.blazegraph.com/browse/BLZG-1341?focusedCommentId=19513&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-19513 for a discussion of this.
      See ASTConstructIterator.isObviouslyDistinct() for relevant logic.

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              Assignee:
              michaelschmidt michaelschmidt
              Reporter:
              bryanthompson bryanthompson
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                Created:
                Updated: