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  1. MariaDB Server
  2. MDEV-8456

Dead code in Item_cond::fix_fields() and Item_func_between::fix_fields()

        Details

        • Type: Bug
        • Status: Closed
        • Priority: Major
        • Resolution: Fixed
        • Affects Version/s: 10.1, 10.0
        • Fix Version/s: 10.1.6
        • Component/s: Optimizer
        • Labels:
          None

          Description

          Item_cond::fix_fields() and Item_func_between::fix_fields() update these optimizer related SELECT_LEX members:

          thd->lex->current_select->cond_count and
thd->lex->current_select->between_count

          The purpose of these members is to allocate optimizer related buffers in:

          • update_ref_and_keys() in sql_select.cc and
          • check_func_dependency() in opt_table_elimination,cc
            and it seems they have no any other purposes..

          This looks like a dead code and the collected values are never used:

          • cond_count and_between_count are later always initialized to 0 before the walk(count_sargable_conds) call in update_ref_and_keys().
          • moreover, using the values collected during fix_fields() would not be correct to allocate optimized related buffers, because the code in fix_fields() does not distinguish between different query parts, so the items can be just a part of the SELECT list rather than a part of WHERE/HAVING/ON.

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                Monty approved the patch by email.

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                bar Alexander Barkov added a comment - Monty approved the patch by email.

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                  • Assignee:
                    bar Alexander Barkov
                    Reporter:
                    bar Alexander Barkov
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                    • Created:
                      Updated:
                      Resolved: