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  1. MariaDB Server
  2. MDEV-9736

Window functions: multiple cursors to read filesort result

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    • Sprint:
      10.2.2-1

      Description

      This is to keep track of a known task:

      Computation of window function value involves moving multiple cursors through the result of filesort:

      • frame bound #1 (Implemented in classes produced by get_frame_cursor())
      • frame bound #2 (Implemented in classes produced by get_frame_cursor())
      • current row ( has no explicit cursor, just calls read_record.read_record()).

      right now, we are using "stub" code that only works when filesort result fits into an in-memory buffer:

      bool clone_read_record(const READ_RECORD *src, READ_RECORD *dst)
      {
        DBUG_ASSERT(src->table->sort.record_pointers);
        DBUG_ASSERT(src->read_record == rr_from_pointers);
        memcpy(dst, src, sizeof(READ_RECORD));
        return false;
      }
      

      This task is about being able to handle the case where filesort result didnt fit into the memory buffer and was partially dumped into a temp. file.

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              Assignee:
              psergei Sergei Petrunia
              Reporter:
              psergei Sergei Petrunia
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                Updated:

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