Slowdown with named snapshots

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    • Type: Improvement
    • Resolution: Done
    • Priority: Critical - P2
    • WT2.7.0
    • Affects Version/s: None
    • Component/s: None
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      The mongodb test jstests/noPassthroughWithMongod/indexbg_interrupts.js takes significantly longer with snapshots enabled (42 min vs 1 min). Most of the time is spent in the convertToCapped command. Profiling shows that the vast majority of the time is spent iterating the update lists in __rec_txn_read and __wt_row_modify.

      My theory is that the existence of a snapshot is preventing splitting a page. This workload creates a new collection and inserts ~100k records into it without creating new snapshots or retiring old ones. I think that the linear scans are causing this to be an O(N^2) operation.

              Assignee:
              Michael Cahill (Inactive)
              Reporter:
              Mathias Stearn
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                Created:
                Updated:
                Resolved: