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  1. MariaDB Server
  2. MDEV-15967

CONNECT engine loses microseconds in timestamps

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    Description

      CONNECT engine truncates microseconds in TIMESTAMP/DATETIME values upon storing them:

      MariaDB [test]> create table tc (t timestamp(6)) engine=CONNECT table_type=DOS file_name='tc.file';
      		 
      Query OK, 0 rows affected (0.03 sec)
      		 
       
      		 
      MariaDB [test]> insert into tc values ('2012-12-12 12:12:12.123456');
      		 
      Query OK, 1 row affected (0.01 sec)
      		 
       
      		 
      MariaDB [test]> select * from tc;
      		 
      +----------------------------+
      		 
      | t                          |
      		 
      +----------------------------+
      		 
      | 2012-12-12 12:12:12.000000 |
      		 
      +----------------------------+
      		 
      1 row in set (0.00 sec)


      $ cat data/test/tc.file
      		 
       1355307132

      As a side-effect, system versioning for CONNECT tables does not work at all.

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          bertrandop Olivier Bertrand added a comment -

          Works as designed.

          bertrandop Olivier Bertrand added a comment - Works as designed.
          bertrandop Olivier Bertrand added a comment -

          Looking at the definition of MariaDB's timestamp in https://mariadb.com/kb/en/library/timestamp/ the timestamp format does not have millisecond even if it says Microseconds with a range of 0 to 6 can also be specified. If not specified, 0 is used.

          Later on, it says that timestamps are internally stored as Epoch Seconds which cannot store millisecond. This is also what CONNECT does for all date data types.

          It seems that later, additional storage was added for milliseconds but CONNECT does not support this.

          bertrandop Olivier Bertrand added a comment - Looking at the definition of MariaDB's timestamp in https://mariadb.com/kb/en/library/timestamp/ the timestamp format does not have millisecond even if it says Microseconds with a range of 0 to 6 can also be specified. If not specified, 0 is used. Later on, it says that timestamps are internally stored as Epoch Seconds which cannot store millisecond. This is also what CONNECT does for all date data types. It seems that later, additional storage was added for milliseconds but CONNECT does not support this.
          bertrandop Olivier Bertrand added a comment -

          I don't understand why table system versioning would need milliseconds. This could be another issue: versioning should be available without milliseconds.

          bertrandop Olivier Bertrand added a comment - I don't understand why table system versioning would need milliseconds. This could be another issue: versioning should be available without milliseconds.

          People

            bertrandop Olivier Bertrand
            elenst Elena Stepanova
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              Updated:
              Resolved:

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