How to add a MongoDB Index

Problem

You want to add a new index to MongoDB, so that you can query over that field quickly.

Solution

Add the index to the server Schema, and then get a CoCo Engineer to add the index to the production MongoDB manually. (Manually adding it ahead of time is preferable to doing it during deploy)

Details

In server/models/(your model).schema, add the index. (Note: Mongoose makes indexes background: true by default here)

Eg: PrepaidSchema.index({'joiners.userID': 1}, {sparse: true})

Then, before deploying this code, ask a CodeCombat engineer to add the index. Make sure to add background: true to the options here. db.prepaids.createIndex({'joiners.userID': 1}, {sparse: true, background: true})

Resources

• MongoDB Index Options