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mongodbmongodb-querymongodb-indexes

Mongodb partial index on one of the indexed field

I want to create partial index on one of the indexed field but I am failing miserably

db.Comment.createIndex(
 { "siteId": 1,
 { { "parent": 1} ,{partialFilterExpression:{parent:{$exists: true}}}},
 "updatedDate": 1,
 "label": 1 } 
);

how to do that?

the field "parent" is the one I want to index partially

In roboMongo I get the error Error: Line 3: Unexpected token {

Solution

  • You pass the partialFilterExpression object as a second parameter to createIndex. See the documentation.

    db.Comment.createIndex(
  { "siteId": 1, "parent": 1, "updatedDate": 1, "label": 1 },
  { partialFilterExpression: { parent: { $exists: true } }
);

    So don't think of it as partially indexing a field; your partial filter expression defines which documents to include in your index.