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  1. MariaDB Server
  2. MDEV-24387

Wrong number of decimal digits in certain UNION/Subqery constellation

Details

    Description

      UNION of an UNSIGNED result, and a NULL result from a subquery, leads to wrong number of decimals. See the following two one liner test queries, which were run with `mysql --column-type-info`. This only started with 10.3.

      MariaDB [test]> select CAST(1 as unsigned) union all select NULL;
      		 
      Field   1:  `CAST(1 as unsigned)`
      		 
      Catalog:    `def`
      		 
      Database:   ``
      		 
      Table:      ``
      		 
      Org_table:  ``
      		 
      Type:       NEWDECIMAL
      		 
      Collation:  binary (63)
      		 
      Length:     2
      		 
      Max_length: 1
      		 
      Decimals:   0
      		 
      Flags:      BINARY NUM 
       
      		 
       
      		 
      +---------------------+
      		 
      | CAST(1 as unsigned) |
      		 
      +---------------------+
      		 
      |                   1 |
      		 
      |                NULL |
      		 
      +---------------------+
      		 
      2 rows in set (0.000 sec)
      		 
       
      		 
      MariaDB [test]> select CAST(1 as unsigned) union all select * from (select NULL) t;
      		 
      Field   1:  `CAST(1 as unsigned)`
      		 
      Catalog:    `def`
      		 
      Database:   ``
      		 
      Table:      ``
      		 
      Org_table:  ``
      		 
      Type:       NEWDECIMAL
      		 
      Collation:  binary (63)
      		 
      Length:     42
      		 
      Max_length: 40
      		 
      Decimals:   39
      		 
      Flags:      BINARY NUM 
       
      		 
       
      		 
      +------------------------------------------+
      		 
      | CAST(1 as unsigned)                      |
      		 
      +------------------------------------------+
      		 
      | 1.00000000000000000000000000000000000000 |
      		 
      |                                     NULL |
      		 
      +------------------------------------------+
      		 
      2 rows in set (0.000 sec)

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        Issue Links

          relates to

          Task - A task that needs to be done. MDEV-12775 Reuse data type aggregation code for hybrid functions and UNION

          • Major - Major loss of function.
          • Closed

          Activity

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            alice Alice Sherepa added a comment -

            it was changed after https://github.com/MariaDB/server/commit/705fc43eaa (MDEV-12775)

            alice Alice Sherepa added a comment - it was changed after https://github.com/MariaDB/server/commit/705fc43eaa ( MDEV-12775 )
            rucha174 Rucha Deodhar added a comment -

            Patch: https://github.com/MariaDB/server/commit/f2392c72cb354224db36066f62dacb228c70d7a0

            rucha174 Rucha Deodhar added a comment - Patch: https://github.com/MariaDB/server/commit/f2392c72cb354224db36066f62dacb228c70d7a0
            bar Alexander Barkov added a comment -

            The patch https://github.com/MariaDB/server/commit/f2392c72cb354224db36066f62dacb228c70d7a0 looks OK to me.

            I suggest to change tests though:

            instead of calling "mysql" command line client, please execute these queries directly in *.test file using --enable_metadata and --disable_metadata around queries.

            This is the usual way how we check result set metadata.

            bar Alexander Barkov added a comment - The patch https://github.com/MariaDB/server/commit/f2392c72cb354224db36066f62dacb228c70d7a0 looks OK to me. I suggest to change tests though: instead of calling "mysql" command line client, please execute these queries directly in *.test file using --enable_metadata and --disable_metadata around queries. This is the usual way how we check result set metadata.
            rucha174 Rucha Deodhar added a comment -

            Patch after latest changes: https://github.com/MariaDB/server/commit/c597d9234c0072a77122f2810212877f1a532d3d

            rucha174 Rucha Deodhar added a comment - Patch after latest changes: https://github.com/MariaDB/server/commit/c597d9234c0072a77122f2810212877f1a532d3d
            bar Alexander Barkov added a comment -

            Ok to push. Thanks!

            bar Alexander Barkov added a comment - Ok to push. Thanks!

            People

              bar Alexander Barkov
              hholzgra Hartmut Holzgraefe
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                Updated:
                Resolved:

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