Take collection size into account for FETCH

XMLWordPrintableJSON

    • Type: Improvement
    • Resolution: Won't Do
    • Priority: Major - P3
    • None
    • Affects Version/s: None
    • Component/s: None
    • Query Optimization
    • None
    • None
    • None
    • None
    • None
    • None
    • None

      We found that the collection size significantly impacts the cost. The incremental cost of a fetch almost doubled when using a collection size of 1M versus 100K. We believe this is due to the same reason as for IXSCAN seeks: larger collection -> deeper B+ tree -> more expensive fetch.

      As the different in cost can be huge, we should take collection size into account. We know the size of the collection inside CBR. It is in CardinalityEstimator::_collCard which should be easy to propagate to CostEstimator.

            Assignee:
            Max Verbinnen
            Reporter:
            Max Verbinnen
            Votes:
            0 Vote for this issue
            Watchers:
            4 Start watching this issue

              Created:
              Updated:
              Resolved: