I use the com.google.appengine.api.datastore.Blob type in my web-application. As it’s mentioned in reference the size of such entity is “Up to 1 megabyte”.
The question is: if I wrap a byte array of size less then 1 megabyte (e.g. 500 KB) into this entity – what would be the actual size of the entry in database – the real size (500 KB) or the maximum size (1MB)?
It will be the actual size of the data. You can tell by looking at the blob viewer in your admin panel.