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Esfand S

Arachnid's bulkupdate at master - GitHub - 0 views

  • The App Engine bulk update library is a library for the App Engine Python runtime, designed to facilitate doing bulk processing of datastore records. It provides a framework for easily performing operations on all the entities matched by any arbitrary datastore query, as well as providing an administrative interface to monitor and control batch update jobs.
Esfand S

Using the new bulkloader - Nick's Blog - 0 views

  • The property map consists of a set of 'property' entries, each of which specifies how to handle a particular property of the model on import and on export. for our Permission kind, the bulkloader has identified 4 properties, plus the __key__ pseudo-property. Each has an 'external_name', and optional import and export transforms, which specify how to translate between the App Engine datastore representation and an external representation.
  • All we had to do here was to remove some of the boilerplate and the extraneous invite_nonce entry, and fill in the kind names for the two reference properties, and we're sorted.
  • we didn't have to write a single line of Python code, or set up an app.yaml, or anything else Python-specific in order to achieve it! Further, the bulkloader took care of generating a mostly-finished configuration file for us, in a format that ensures the data we download can be re-uploaded again without loss of fidelity.
Esfand S

Creating, Getting and Deleting Data - Google App Engine - Google Code - 0 views

  • Tip: If the app creates a new object and gives it the same string ID as another object of the same kind (and the same entity group parent), saving the new object overwrites the other object in the datastore. To detect whether a string ID is already in use prior to creating a new object, you can use a transaction to attempt to get an entity with a given ID, then create one if it doesn't exist. See Transactions.
  • There are 4 types of primary key fields:
Esfand S

Google App Engine Task Queues, Push vs. Pull Paradigm, and Web Hooks | Sachin Rekhi - 0 views

  • Task Queue is defined as a mechanism to synchronously distribute a sequence of tasks among parallel threads of execution. The global problem is broken down into tasks and the tasks are enqueued onto the queue. Parallel threads of execution pull tasks from the queue and perform computations on the tasks. The runtime system is responsible for managing thread accesses to the tasks in the queue as well as ensuring proper queue usage (i.e. dequeuing from an empty queue should not be allowed).
  • GAE Task Queue provides a push model. Instead of having an arbitrary number of worker processes constantly polling for available tasks, GAE Task Queue instead pushes work to workers when tasks are available. This work is then processed by the existing auto-scaling GAE infrastructure, allowing you to not have to worry about scaling up and down workers. You simply define the maximum rates of processing and GAE takes care of farming out the tasks to workers appropriately.
  • What is also compelling about GAE Task Queue is its use of web hooks as the description of a task unit. When you break it down, an individual task consists of the code to execute for that task as well as the individual data input for that specific task.
  • ...2 more annotations...
  • As far as the data input, the GET querystring params or HTTP POST body provide suitable mechanisms for providing any kind of input. In this way, a task description is simply a URL that handles the request and a set of input parameters to that request.
  • a given task has a 30 second deadline. That means any individual task cannot perform more than 30s of computation, including getting data from the data store, calling third party APIs, computing aggregations, etc.
Esfand S

Developer's Notes: Lists and Nulls in Google App Engine Datastore - 0 views

  • So the summary is: do not store nulls into Lists, otherwise you will get into a problem in future.
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