@Persistent(serialized = "true") vs @Persistent

[applehund]

Hi there, can anyone explain the pros & cons of these two styles? Like if I have an Integer member variable:

@Persistent

private Integer foo;

@Persistent(serialized = "true")

private Integer foo;

I do know that with the serialized version I have to always mark it dirty with JDOHelper.makeDirty(...).

Is there a speed performance boost for serialized? A storage size decrease? Why wouldn't I just use @Persistent always?

Thanks everyone!

[applehund]

*bump bump*

[Amy Unruh]

hi,

The app engine JDO documentation goes into this in more detail-- take a look at the discussion of the field types.

The https://developers.google.com/appengine/docs/java/datastore/jdo/dataclasses

A serialized field is stored as a blob property.  You can use it to set a field of your instance to some (serializable) object, with the serialization and deserialization handled for you. Blob values are not indexed and cannot be used in query filters or sort orders. 

You might want to use a serialized field if you have an object that should be part of an entity, and is not a 'core type' (or supported collection), and whose contents don't need to be indexed-- in that case it's often simplest to just serialize it wholesale.

If your field is a core type (like Integer), you don't need to serialize it -- just annotate it as 'unindexed' if you don't want it indexed.  

*bump bump*

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[applehund]

Thanks Amy! This makes sense :)

Another question I have is do list objects that are serialized still count towards the 5000 member field limit? So currently if I have a GAE object with:

@Persistent

private List<Object>foo;

and foo contains 5000+ objects then I can't load it from the datastore. Does this change if foo is stored as a serialized blob property instead?

@Persistent(serialized = "true")

private List<Object>foo;

Since it's not indexed?

Thanks!