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CM Wang

Question CM Wang · Jul 16, 2017

How to index a class

#Caché #Indexing #Object Data Model

I have two persistent classes defined. Lets call it Parent and Child.

Child class is one of the property of Parent Class.

I would like to define a index on Child class.

So what is the default behaviour I defined a index on a non simple data type member?

Any possibility that I could customized the behaviour ? For example. Child class has three properties.

Could I configure the index to index any combinations of these three properties?

Thanks for your help.

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Eduard Lebedyuk · Jul 16, 2017

It depends on a queries you want to run. For example you want to get all parents' ids which have a child with a specific property value. In a child class you can index for one or several properties, and execute this query:

SELECT parentId
FROM child
WHERE propertyA = 'value'

Documentation on indexes.

Or you can define a computed property in your parent class and index that.

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