Mongodb - Use a regex search to match embedded documents

Question

I have a Mongo Collection :

db.sCriteria.insert({criteria : {a:"1",b:"2",c:"3"}})
db.sCriteria.insert({criteria : {a:"1",d:"2",e:"3"}})

The properties of the embedded document "criteria" can vary a lot so I chose to index the whole object :

db.sCriteria.ensureIndex({criteria : 1})

And my queries are always against the entire object to use the index. Ex :

db.sCriteria.find({criteria : {a:"1",b:"2",c:"3"}}).count() 
1
db.sCriteria.find({criteria : {a:"1",b:"2"}}).count() 
0

What I want to be able to do is to use regex for some property. For example :

db.sCriteria.find({criteria : {a:"1",b:"2",c:/3/}}).count()

This always gives 0 results

Is there a way to do this and use the index?

Sede · Accepted Answer · 2015-07-14 13:15:28Z

2

Your query may not return any document if what you are querying is subdocument because the field order matter.The best thing to do is to create a coumpound indexes and use the dot notation.

db.sCriteria.count({ "criteria.a": "1", "criteria.b": "2", "criteria.c": /3/})

edited Jul 14, 2015 at 13:15

answered Jul 14, 2015 at 12:53

Sede

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3 Comments

Monta Over a year ago

In this case my index will not be used. And I can't create an index for each property because in reality I have other properties with which I index the criteria object, which will make it very complex

Sede Over a year ago

you don't need to index every fields in your subdocument absolutely not. you can use compound indexes

Monta Over a year ago

The index I described is only used to find the whole object. It's not used with your proposition

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