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  1. MariaDB Server
  2. MDEV-7487

Semi-join optimization for single-table UPDATE/DELETEs

        Details

        • Type: Task
        • Status: Open
        • Priority: Major
        • Resolution: Unresolved
        • Fix Version/s: 10.2
        • Component/s: Optimizer
        • Labels:
          None

          Description

          Currently, single-table UPDATE/DELETE statements cannot take advantage of semi-join optimizations. This is because semi-join optimizations are parts of join optimization (which is not invoked for single-table UPDATE/DELETE).

          This task is about

          • detecting UPDATE/DELETEs that can use semi-join optimizations
          • switching those queries to be processed as multi-table UPDATE/DELETEs. This will enable semi-join optimizations.

          Note that we do similar things for VIEWs: UPDATE multi_table_view SET =... is switched to be processed as multi-table UPDATE as soon as the server discovers that we're updating a multi-table VIEW.

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                psergey Sergei Petrunia added a comment -

                See also MDEV-7220 for a related discussion. Non-semijoin optimizations (e.g. Materialization vs IN->EXISTS) would are not used in single-table UPDATE/DELETE, either. And that is a deficiency, too.

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                psergey Sergei Petrunia added a comment - See also MDEV-7220 for a related discussion. Non-semijoin optimizations (e.g. Materialization vs IN->EXISTS) would are not used in single-table UPDATE/DELETE, either. And that is a deficiency, too.

                  People

                  • Assignee:
                    cvicentiu Vicentiu Ciorbaru
                    Reporter:
                    psergey Sergei Petrunia
                  • Votes:
                    1 Vote for this issue
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                    Dates

                    • Created:
                      Updated: