Uploaded image for project: 'MariaDB Server'
  1. MariaDB Server
  2. MDEV-15864

Index condition in ANALYSE FORMAT=JSON shows the same condition twice

    XMLWordPrintable

    Details

    • Type: Bug
    • Status: Open (View Workflow)
    • Priority: Minor
    • Resolution: Unresolved
    • Affects Version/s: 10.1, 10.2
    • Fix Version/s: 10.1
    • Component/s: Optimizer
    • Labels:
      None

      Description

      analyze format=json select * from t1,t1_subsets where t1.subset_id IS NOT NULL and t1.subset_id= t1_subsets.id;
      ANALYZE
      {
        "query_block": {
          "select_id": 1,
          "r_loops": 1,
          "r_total_time_ms": 0.0594,
          "table": {
            "table_name": "t1",
            "access_type": "range",
            "possible_keys": ["t1_subset_id"],
            "key": "t1_subset_id",
            "key_length": "5",
            "used_key_parts": ["subset_id"],
            "r_loops": 1,
            "rows": 3,
            "r_rows": 0,
            "r_total_time_ms": 0.0226,
            "filtered": 100,
            "r_filtered": 100,
            "index_condition": "((t1.subset_id is not null) and (t1.subset_id is not null))"
          },
          "table": {
            "table_name": "t1_subsets",
            "access_type": "eq_ref",
            "possible_keys": ["PRIMARY"],
            "key": "PRIMARY",
            "key_length": "4",
            "used_key_parts": ["id"],
            "ref": ["test.t1.subset_id"],
            "r_loops": 0,
            "rows": 1,
            "r_rows": null,
            "filtered": 100,
            "r_filtered": null,
            "index_condition": "(t1.subset_id = t1_subsets.`id`)"
          }
        }
      }
      

      So if you look at the first table t1, we have an index condition as
      "index_condition": "((t1.subset_id is not null) and (t1.subset_id is not null))". So we have the same condition twice here which i think is adding an overhead and we should remove the duplication here.

        Attachments

          Activity

            People

            • Assignee:
              varun Varun Gupta
              Reporter:
              varun Varun Gupta
            • Votes:
              0 Vote for this issue
              Watchers:
              1 Start watching this issue

              Dates

              • Created:
                Updated: