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  1. MariaDB Server
  2. MDEV-13916

Enforce check constraint on JSON type

Details

    • Task
    • Status: Closed (View Workflow)
    • Major
    • Resolution: Fixed
    • 10.4.3
    • JSON
    • None

    Description

      Since there's no context where someone will want a JSON type without the constraint, and excluding it causes compatibility problems with MySQL, why not map

      CREATE TABLE t (j JSON);

      to

      CREATE TABLE t (
      		 
        j JSON 
        CHECK (JSON_VALID(j))
      		 
      );

      Attachments

        Issue Links

          relates to

          Task - A task that needs to be done. MDEV-9144 JSON data type

          • Major - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-13313 JSON type alias is insufficiently compatible

          • Major - Major loss of function.
          • Closed

          Activity

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            greenman Ian Gilfillan created issue -
            greenman Ian Gilfillan made changes -
            Field Original Value New Value
            serg Sergei Golubchik made changes -
            Description Since there's no context where someone will want a JSON type without the constraint, and excluding it causes compatibility problems with MySQL, why not map
            {{code}}
            CREATE TABLE t (j JSON);
            {{code}}
            to
            {{code}}
            CREATE TABLE t (
              j JSON
              CHECK (JSON_VALID(j))
            );
            {{code}}             		Since there's no context where someone will want a JSON type without the constraint, and excluding it causes compatibility problems with MySQL, why not map
            {code:sql}
            CREATE TABLE t (j JSON);
            {code}
            to
            {code:sql}
            CREATE TABLE t (
              j JSON
              CHECK (JSON_VALID(j))
            );
            {code}
            serg Sergei Golubchik made changes -
            serg Sergei Golubchik made changes -
            serg Sergei Golubchik made changes -
            serg Sergei Golubchik added a comment -

            I considered that in MDEV-13313. To quote

            auto-adding a constraint is questionable. An unexpected constraint in the table definition, performance implications, strange errors if one manually specifies some constraint for this column.

            that's why I haven't done it. Basically, I can see some users being for and some being against this feature and I cannot say what approach will work best for them all.

            serg Sergei Golubchik added a comment - I considered that in MDEV-13313 . To quote auto-adding a constraint is questionable. An unexpected constraint in the table definition, performance implications, strange errors if one manually specifies some constraint for this column. that's why I haven't done it. Basically, I can see some users being for and some being against this feature and I cannot say what approach will work best for them all.
            ralf.gebhardt Ralf Gebhardt made changes -
            Epic Link PT-76 [ 68557 ]
            ralf.gebhardt Ralf Gebhardt made changes -
            Assignee Alexey Botchkov [ holyfoot ]
            ralf.gebhardt Ralf Gebhardt made changes -
            Fix Version/s 10.4 [ 22408 ]
            monty Michael Widenius made changes -
            Assignee Alexey Botchkov [ holyfoot ] Michael Widenius [ monty ]
            monty Michael Widenius added a comment -

            Talked with Sergei and we agree to do this with two small changes:

            • The resulting field type will be TEXT, not JSON as we don't yet have a JSON type
            • MariaDB will add an automatic constraint JSON_VALID(field_name) for all JSON fields that doesn't already have a constraint.
              This is to avoid getting things like 'JSON_VALID(field_name) AND JSON_VALID(field_name)' in the check constraint. This is a small
              restriction and one can easily go around it by using table level constraint for "field_name"
            monty Michael Widenius added a comment - Talked with Sergei and we agree to do this with two small changes: The resulting field type will be TEXT, not JSON as we don't yet have a JSON type MariaDB will add an automatic constraint JSON_VALID(field_name) for all JSON fields that doesn't already have a constraint. This is to avoid getting things like 'JSON_VALID(field_name) AND JSON_VALID(field_name)' in the check constraint. This is a small restriction and one can easily go around it by using table level constraint for "field_name"
            monty Michael Widenius made changes -
            Status Open [ 1 ] In Progress [ 3 ]
            monty Michael Widenius added a comment -

            Pushed into 10.4

            monty Michael Widenius added a comment - Pushed into 10.4
            monty Michael Widenius made changes -
            Fix Version/s 10.4.3 [ 23230 ]
            Fix Version/s 10.4 [ 22408 ]
            Resolution Fixed [ 1 ]
            Status In Progress [ 3 ] Closed [ 6 ]
            serg Sergei Golubchik made changes -
            Workflow MariaDB v3 [ 82802 ] MariaDB v4 [ 133351 ]

            People

              monty Michael Widenius
              greenman Ian Gilfillan
              Votes:
              1 Vote for this issue
              Watchers:
              7 Start watching this issue

              Dates

                Created:
                Updated:
                Resolved:

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