Hi Carlos, Entities are always fetched in entirety - there's no way to query for only specific fields in an entity. In cases where you have a large Blob such as an uploaded image, it's often a good idea to split it into 'data' and 'metadata' entities, so you only fetch the actual image when you need to return it.
-Nick Johnson On Sun, Sep 20, 2009 at 12:56 PM, Carlos <[email protected]> wrote: > > I've been looking closely at the datastore quotas, and couldn't > readily find an answer to this. > > Storage is cheap, so no one should ever fear storing large amounts of > data safely in the datastore (and paying for it if necessary). That's > what it was built for. > > However, I'm wondering about communication efficiency between the > datastore and an application. In the datastore overview, the docs > say: > > "A query can also limit the number of results returned by the > datastore to conserve memory and run time." > > and then the "Getting, Creating, and Deleting data" page says: > > "Query and GqlQuery objects do not execute the query until the > application tries to access the results. When the application accesses > results, the query is executed, and results are loaded into memory as > instances of the model class for the query." > > My question is, does "accessing the results" retrieve all of the > entity properties, meaning it counts against the "Data Received from > API" quota? > > > Imagine a data model where you store images. Sometimes you just want > the metadata about the image (name, width, height, tags) and sometimes > you want to retrieve the image blob itself. Since neither Query or > GqlQuery let you specify which properties to return, does the image > blob get returned every time you fetch results? I'd think not with > the proper use of indexes, but I can't find documentation that says > so. The "Data Received from API" quota is huge, but my concern is the > "conserve memory and run time" in general. > > > > > > > -- Nick Johnson, Developer Programs Engineer, App Engine Google Ireland Ltd. :: Registered in Dublin, Ireland, Registration Number: 368047 --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~----------~----~----~----~------~----~------~--~---
