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  1. MariaDB Server
  2. MDEV-15159

NULL is treated as 0 in CTE

Details

    Description

      testcase:

      WITH RECURSIVE cte AS (
      		 
      	SELECT 1 AS a UNION ALL
      		 
      	SELECT NULL FROM cte WHERE a IS NOT NULL)
      		 
      SELECT * FROM cte;

      it produces an infinite loop, so will get (max_recursive_iterations) strings with 0 (plus 1 sting with 1)
      if we use union distinct:

      MariaDB [test]> WITH RECURSIVE cte AS (
      		 
          -> SELECT 1 AS a UNION 
          -> SELECT NULL FROM cte WHERE a IS NOT NULL)
      		 
          -> SELECT * FROM cte;
      		 
      +---+
      		 
      | a |
      		 
      +---+
      		 
      | 1 |
      		 
      | 0 |
      		 
      +---+
      		 
      2 rows in set (0.001 sec)

      Attachments

        Issue Links

          relates to

          Bug - A problem which impairs or prevents the functions of the product. MDEV-16505 NULL is treated as 0 in CTE

          • Major - Major loss of function.
          • Open

          Task - A task that needs to be done. MDEV-15447 Import CTE tests from MySQL 8

          • Major - Major loss of function.
          • Stalled

          Activity

            Transition Time In Source Status Execution Times
            Igor Babaev (Inactive) made transition -
            Open In Progress
            		102d 5h 49m 1
            Igor Babaev (Inactive) made transition -
            In Progress Closed
            		22h 38m 1

            People

              igor Igor Babaev (Inactive)
              alice Alice Sherepa
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              Dates

                Created:
                Updated:
                Resolved:

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