CODEWITHSUNDEEP
mongodbindexing
MongoDBDeveloper
MongoDBDeveloper

Reputation: 41

Indexes with $in or $or

My document structure is something like this 

{
    _id: "id1",
    field1: "val1",
    field2: "val2",
    outcome: "ABC"
}

I have created index on outcome field. I have to find all documents with {outcome:"ABC"} or {outcome:"XYZ"} only. There is no major difference in query execution time if i use $or or $in. e.g 

db.coll.find({$or:[{outcome:"ABC"},{outcome:"XYZ"}]}); 
db.coll.find({outcome:{$in:["ABC","XYZ"]}});

Which operator should i use $or or $in in this case? And why? Any help would be appreciated.

Upvotes: 2

Views: 59

Answers (1)

zangw
zangw

Reputation: 48506

MongoDB docs

When using $or with <expressions> that are equality checks for the value of the same field, use the $in operator instead of the $or operator.

For example, to select all documents in the inventory collection where the quantity field value equals either 20 or 50, use the $in operator:

db.inventory.find ( { quantity: { $in: [20, 50] } } )

So in your case it is better to use

db.coll.find({outcome:{$in:["ABC","XYZ"]}});

Upvotes: 2

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