Typically a query by example consists of AND operations. 

handler.query ({age:5, height:0.7});

Using constraints just gives us the opportunity for more complicated AND operations

var c = enums.CONSTRAINTS;
handler.query ( age: handler.constraints([[c.LTE,.9],[c.GTE,.5]]), age: handler.constraint([c.LT,7]));

Sometimes you want to to OR operations – for example people under 10 or over 25. Not all underlying databases even have an OR capability (for example DataStore), but database abstraction provides a consistent way to do OR operations across all supported back ends.

How to do ORS

The following syntax applies to all backends
Lets say you want to do these 2 queries and combine the results

handler.query ({color:'red'});
handler.query ({size:'big'});

Just make an array of queries

handler.query ([{size:'big'},{color:'red'}]);

You can mix in constraints as well if you want

var c = enums.CONSTRAINTS;
handler.query ([ {"location.country":"usa", "location.state":handler.constraints([c.IN,["il","ny"]])}, {"location.country":"uk", "location.city":"london"} ]);

Duplicates are automatically removed (if records qualify for more than one query they are returned only once)

See Database abstraction with google apps script for more on this.

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