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  1. Apache Cassandra
  2. CASSANDRA-17357

Snapshot true size computation does not include secondary indexes

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Details

    • Bug
    • Status: Resolved
    • Normal
    • Resolution: Duplicate
    • None
    • Local/Snapshots
    • None
    • Correctness - API / Semantic Definition
    • Low
    • Normal
    • Code Inspection
    • All
    • None

    Description

      The true size is supposed to show the total size of the snapshot minus any live sstables.

      Nevertheless, sstables from secondary indexes are not included in the computation of the true size, causing a mismatch between the true size and snapshot size when there are indexes and no live sstables.

      It's possible to fetch the global snapshot size per table and indexes separately via nodetool tablestats, but not for individual snapshots.

      This behavior seems to be there since before 3.0, so I think it has always been like this.

      Reproduction steps:

      % ccm node1 nodetool -- snapshot -t test test_ks
      
      Requested creating snapshot(s) for [test_ks] with snapshot name [test]
      Snapshot directory: test
      
      % ccm node1 nodetool listsnapshots
      
      Snapshot Details:
      Snapshot name Keyspace name Column family name True size Size on disk
      test          test_ks       tbl                0 bytes   10.76 KB
      
      Total TrueDiskSpaceUsed: 0 bytes
      
      % ccm node1 nodetool tablestats test_ks.tbl | grep -i snapshot
          Space used by snapshots (total): 0
      
      % ccm node1 nodetool tablestats test_ks.tbl.tbl_val_idx | grep -i snapshot
          Space used by snapshots (total): 0
      
      % ccm node1 nodetool compact test_ks tbl.tbl_val_idx
      
      % ccm node1 nodetool compact test_ks tbl_val_idx
      
      % ccm node1 nodetool tablestats test_ks.tbl | grep -i snapshot
          Space used by snapshots (total): 5027
      
      % ccm node1 nodetool tablestats test_ks.tbl.tbl_val_idx | grep -i snapshot
          Space used by snapshots (total): 5060
      
      % ccm node1 nodetool listsnapshots
      
      Snapshot Details:
      Snapshot name Keyspace name Column family name True size Size on disk
      test          test_ks       tbl                4.91 KB   10.76 KB
      
      Total TrueDiskSpaceUsed: 4.91 KB
      

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              paulo Paulo Motta
              paulo Paulo Motta
              Paulo Motta
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              Dates

                Created:
                Updated:
                Resolved: