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  1. WiredTiger
  2. WT-2042

Slowdown with named snapshots

    • Type: Icon: Improvement Improvement
    • Resolution: Done
    • Priority: Icon: Critical - P2 Critical - P2
    • WT2.7.0
    • Affects Version/s: None
    • Component/s: None
    • None

      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@mongodb.com Michael Cahill (Inactive)
            Reporter:
            mathias@mongodb.com Mathias Stearn
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              Created:
              Updated:
              Resolved: