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  1. Blazegraph (by SYSTAP)
  2. BLZG-741

Extend ASTStaticJoinOptimizer to reorder arbitrary length path nodes.

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    Details

    • Type: New Feature
    • Status: In Progress
    • Resolution: Unresolved
    • Affects Version/s: BIGDATA_RELEASE_1_2_0
    • Fix Version/s: None
    • Labels:
      None

      Description

      The static join optimizer currently only considers statement patterns for re-ordering. It needs to be extended to take into account other types of join nodes, including the ArbitraryLengthPathNode (property paths with a '*' or '+' operator).

      This query, submitted by an open-source user, demonstrates the problem well (when run on his data):

      SELECT distinct ?a WHERE {

      ?a np:precision/rdfs:subClassOf+ CV:3.4.19.-

      }

      This query can be re-written as follows:

      SELECT distinct ?a WHERE {

      ?a np:precision ?b .

      ?b rdfs:subClassOf+ CV:3.4.19.- .

      }

      The real cardinalities of this query are as follows:

      SELECT distinct ?a WHERE {

      ?a np:precision ?b . #cardinality=4266240

      ?b rdfs:subClassOf+ CV:3.4.19.- . #cardinality=15

      }

      When I manually force the property path to run first, the query completes almost instantly. The static join optimizer needs to get this right automatically.

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            Assignee:
            michaelschmidt michaelschmidt
            Reporter:
            mikepersonick mikepersonick
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              Dates

              Created:
              Updated: