将双点转换为双点

Question

I have a requirement to change a field from double to Double in hybris typeSystem and was wondering if it actually creates a new database field or just changes the type in app layer. Thanks in advance.

Answer 1

After the items.xml change and system update the data base field remained the same type. All reads and write are from the same column. So, the answer to my question is no, the column type does not change in database. Only the application layer (model) has changed the field from double to Double.

Answer 2

You have the mapping in core-advanced-deployment.xml.

The mapping depends on DB :

    <type-mapping type="java.lang.Double" persistence-type="decimal(30,8)" />
    <type-mapping type="double" persistence-type="decimal(30,8) DEFAULT 0" />

or:

    <type-mapping type="java.lang.Double" persistence-type="double"  />
    <type-mapping type="double" persistence-type="double default 0"  />

or:

     <type-mapping type="java.lang.Double" persistence-type="float" />
     <type-mapping type="double" persistence-type="float default 0" />

So you see that it's currently map that's why you can do that and you don't see change in the DB.

Note that changing a type is strongly discouraged because you can switch to uncompatble type. For instance if you have a column of String you can't migrate it to Number for example because a string is not always parseable in a number.