[jira] [Created] (IOTDB-1158) Add nullable support for any datatype

["sunjincheng (Jira)" <ji...@apache.org>]

sunjincheng created IOTDB-1158:
----------------------------------

             Summary: Add nullable support for any datatype
                 Key: IOTDB-1158
                 URL: https://issues.apache.org/jira/browse/IOTDB-1158
             Project: Apache IoTDB
          Issue Type: New Feature
          Components: Core/Engine
            Reporter: sunjincheng
            Assignee: sunjincheng
         Attachments: image-2021-02-17-08-58-46-610.png

DDL of many databases can support not null syntax, such as MySQL [1]:
{code:java}
CREATE TABLE order (
    item VARCHAR(255) NOT NULL,
    amount FLOAT NOT NULL,
    deal_date DATE
);
{code}
A column may contain only one `NOT NULL` constraint which specifies a rule that the column must not contain any `NULL` value. In other words, by default, `NULL` value is allowed.

For performance reasons, IoTDB does not support `NULL` value by default. Instead, it supports some business scenarios in the form of 'NaN'. As shown in the figure below:

!image-2021-02-17-08-58-46-610.png!

Therefore, in this JIRA., we will discuss whether we need to support `NULL` value and how to support `NULL` values in IoTDB, including session API and SQL API. I'd like to provide a draft of how to support the design, if you think this feature is necessary.

What are your thoughts?

[1] [https://www.mysqltutorial.org/mysql-not-null-constraint/]



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