delta indexes in sphinx on a child node- thinkingsphinx

I have a model restaurant and offers ( has_many :offers) , The sphinx index it self is on the restaurant level . I want to have a delt开发者_JAVA技巧a index which is based on new offers for restaurants or update for current one. What's the best way to do that ?

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I think that this question could be useful for your problem:

Using Delta Indexes for associations in Thinking Sphinx