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Google App Engine Tips and Tricks: Prebuilding Indexes using a non default version

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(This’ll be a shorter post than usual.)

Waiting for indexes to build can be drag; indexes need to be built before Entities even exist and can take longer than needed if the global index building workflow is backed up since mass building is a shared resource.

One little known trick is to pre-build indexes before your application needs them by deploying a non-default version. Your application can have many versions. In Java App Engine, this is defined in the version tag of appengine-web.xml. In Python, this is defined in the version YAML element. The Java Eclipse plugin even has a screen where the version can be set (Click the App Engine icon, then “Project Settings”:

Because all applications share the same datastore, the required indexes will be built once your push your application containing the indexes configuration file with the new, required indexes. Hopefully, by the time you are ready to push your real version, the indexes will have completed building.

In general, it is a best practice to maintain a staging version of your application for testing against live data. App Engine makes this so easy it’s trivial: deploy code tagged with a new “version”. Your application is accessible at http://VERSION.latest.APPID.appspot.com (note that VERSION is a String, not a integer or decimal number) – this is a handy and powerful trick to validating a new test or staging version. When you have enough confidence in your application, browse to the Admin Console, click the radio button associated with your new version, and click “Make Default.”

Versioning has never been so easy. No configuring load balancers, rolling deploys, symlinking, restarting edge caches, etc.

Happy hacking.

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Written by Ikai Lan

July 12, 2010 at 12:34 pm

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