/nds

A Go (golang) Google App Engine datastore package with strongly consistent caching.

Primary LanguageGoApache License 2.0Apache-2.0

nds (v2 - EXPERIMENTAL)

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Package github.com/qedus/nds is a Google Cloud Datastore API for Go that uses a cache backend to cache all datastore requests. Memcache is only supported on Google AppEngine Standard, but the package can be used for any other implemented cache backend on any platform (local, Google Compute, AWS, etc.). This package guarantees strong cache consistency when using nds.Client.Get* and nds.Client.Put*, meaning you will never get data from a stale cache.

Exposed parts of this API are the same as the official one distributed by Google (code.google.com/go/datastore). However, underneath github.com/qedus/nds uses a caching stategy similar to the GAE Python NDB API. In fact the caching strategy used here even fixes one or two of the Python NDB caching consistency bugs.

You can find the API documentation at http://godoc.org/github.com/qedus/nds.

One other benefit is that the standard datastore.Client.GetMulti, datastore.Client.PutMulti and datastore.Client.DeleteMulti functions only allow you to work with a maximum of 1000, 500 and 500 entities per call respectively. The nds.Client.GetMulti, nds.Client.PutMulti and nds.Client.DeleteMulti functions in this package allow you to work with as many entities as you need (within timeout limits) by concurrently calling the appropriate datastore function until your request is fulfilled.

How To Use

You can use this package in exactly the same way you would use code.google.com/go/datastore.Client for methods provided by nds.Client. However, it is important that you use a nds.Client entirely within your code. Do not mix use of those functions with the code.google.com/go/datastore.Client equivalents as you will be liable to get stale datastore entities from github.com/qedus/nds.

Ultimately all you need to do is:

  • import github.com/qedus/nds/v2
  • use nds.NewClient instead of datastore.NewClient, providing a cache configuration to the new client creation function.
  • replace datastore.Transaction -> nds.Transaction
  • if using (*datastore.Query).Transaction for queries within transactions, switch to the (*nds.Transaction).Query helper.