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  1. Couchbase Server
  2. MB-7477

Slow down in disk persistance when updating items in heavy DGM

    Details

    • Type: Improvement
    • Status: Closed
    • Priority: Major
    • Resolution: Duplicate
    • Affects Version/s: 1.8.1, 2.0
    • Fix Version/s: 2.1.0
    • Component/s: storage-engine
    • Security Level: Public
    • Labels:
      None

      Description

      When updating items in heavy DGM (40% resident), the disk drain is slower than draining of new items.

      Ex:
      500 items per second for new items, but only 300 for updates.

      Loading 20K items into a cluster of 2 nodes at 250 ops with 1 replica.

      We loaded 500K items, pushing the resident ratio down to 40%, then updated the same 500K items, during this update phase the disk drain rate dropped down to 60% of what it was before.

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        Activity

        Hide
        dustin Dustin Sallings (Inactive) added a comment - - edited

        Insert vs. update path in the hash table.

        A couple people have asked me why I would expect update to be slower. Here's what the current code looks like.

        Show
        dustin Dustin Sallings (Inactive) added a comment - - edited Insert vs. update path in the hash table. A couple people have asked me why I would expect update to be slower. Here's what the current code looks like.
        Hide
        dustin Dustin Sallings (Inactive) added a comment -

        Also, I didn't highlight them, but notice the four additional stat adjustments in the update path.

        Show
        dustin Dustin Sallings (Inactive) added a comment - Also, I didn't highlight them, but notice the four additional stat adjustments in the update path.
        Hide
        jin Jin Lim (Inactive) added a comment -

        We are going to address this issue while working on multi-reader/write + batch enhancement.

        Show
        jin Jin Lim (Inactive) added a comment - We are going to address this issue while working on multi-reader/write + batch enhancement.
        Hide
        jin Jin Lim (Inactive) added a comment -

        MB-7518 & MB-7519 have been created to address this issue in 2.0.2.

        Show
        jin Jin Lim (Inactive) added a comment - MB-7518 & MB-7519 have been created to address this issue in 2.0.2.
        Hide
        jin Jin Lim (Inactive) added a comment - - edited

        Please move this ticket to appropriate state as above engineering bugs have been created to track the issue.

        Show
        jin Jin Lim (Inactive) added a comment - - edited Please move this ticket to appropriate state as above engineering bugs have been created to track the issue.
        Hide
        maria Maria McDuff (Inactive) added a comment -
        Show
        maria Maria McDuff (Inactive) added a comment - MB-7518

          People

          • Assignee:
            james.mauss James Mauss
            Reporter:
            james.mauss James Mauss
          • Votes:
            0 Vote for this issue
            Watchers:
            4 Start watching this issue

            Dates

            • Created:
              Updated:
              Resolved:

              Gerrit Reviews

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