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  1. MariaDB Server
  2. MDEV-4649

SQL PARSER - unsigned number optimization - could return Impossible Where

        Details

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

          Description

          Hi guys, i found a optimization (maybe a bug?) that could be 'easly' optimized, check this query...

          CREATE TABLE A (I INT UNSIGNED);
INSERT INTO A VALUES (1),(2),(3),(4)
EXPLAIN
SELECT COUNT(*)FROM A WHERE I<0

          this return 4 rows...

          but since "I" Column is unsigned it could return IMPOSSIBLE Where, right? (-1 don't exists to unsigned...)

          i'm thinking about this optimization, and this other optimization (MDEV-4419) could allow some (many) queries to run faster

          in SHOW STATUS LIKE 'handler_re%'
          i see 4 rows being read when i execute the <0 query
          in other words, it's reading data from disk (maybe a bug in optimizer)

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                  • Assignee:
                    Unassigned
                    Reporter:
                    rspadim roberto spadim
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                    • Created:
                      Updated: