Kentaro Hayashi
null+****@clear*****
Mon May 1 17:26:06 JST 2017
Kentaro Hayashi 2017-05-01 17:26:06 +0900 (Mon, 01 May 2017) New Revision: 3c55c6eeb2940bf4a15c4ba709a2acc548526d25 https://github.com/mroonga/mroonga/commit/3c55c6eeb2940bf4a15c4ba709a2acc548526d25 Message: doc: update limitations about column ref. https://gitter.im/groonga/ja?at=58c0aa797ceae5376a8ed71e Reported by @bignum_twitter. Thanks!!! Modified files: doc/source/reference/limitations.rst Modified: doc/source/reference/limitations.rst (+13 -2) =================================================================== --- doc/source/reference/limitations.rst 2017-04-29 17:45:45 +0900 (49d46c4) +++ doc/source/reference/limitations.rst 2017-05-01 17:26:06 +0900 (beafe7c) @@ -39,15 +39,26 @@ Confirm by ``SHOW TABLE STATUS`` or ``SHOW INDEX FROM ...`` whether your table d Limitations about the value of columns -------------------------------------- -There is a limitation about DATE, DATETIME column in storage mode. +There is a limitation about the value of column in storage mode. -mroonga storage engine automatically convert 0 into 1 as the value of month or date. +Mroonga storage engine executes automatic conversion against the value NULL. + +For example, if the value NULL is used in ``DATE`` or ``DATETIME`` +columns, Mroonga storage engine automatically converts 0 into 1 as the +value of month or date. Thus, the value 0 is treated as the 1st month (January) of the year or the 1st date of the month. And more, the value NULL is treated as the value of UNIX time 0 (1970-01-01 00:00:00). +This kind of automatic conversion is not restricted to only ``DATE`` +or ``DATETIME`` types. + +The value NULL is converted into the default value of columns. In most +cases, it will be converted into empty string for column which belongs +to type of string, 0 for column which belongs to type of numeric. + Here is an example to show behavior described above. .. code-block:: sql -------------- next part -------------- HTML����������������������������...Download