Text search on mongodb - mongodb

Question

I have a users collection in Mongo DB having 55L users. The collection is shared across 10 nodes.
There is a field "email" in the collection which stores the email address of the users.
I want to perform a text-based search on this field. I want to search for "mail" and the result should list all documents which have the substring "mail".
I tried with regex but it impacts performance due to collection size.
I tried creating a text index on "email" but it does not support partial search on tokens.
Collection example mentioned below
{ "_id" : ObjectId("5b90e5ffe34b5891eb4c32f6"), "email" : "anand#gmail.com" }
{ "_id" : ObjectId("5b90e64ee34b5891eb4c32f7"), "email" : "kumar.anand#hotmail.com" }
{ "_id" : ObjectId("5b90e65ae34b5891eb4c32f8"), "email" : "ankit#gmail.com" }
{ "_id" : ObjectId("5b90e661e34b5891eb4c32f9"), "email" : "rahul#rediff.com" }
{ "_id" : ObjectId("5b90e67de34b5891eb4c32fa"), "email" : "prachi#gmail.com" }
{ "_id" : ObjectId("5b90f0ab46ef1951e6afb822"), "email" : "bb#yahoo.com", "name" : "ankit" }
{ "_id" : ObjectId("5b965d4ad5bc80bda9885181"), "email" : "amit#gmail.com", "rating" : [ 5, 6 ] }
{ "_id" : ObjectId("5b965d56d5bc80bda9885182"), "email" : "amit33#gmail.com", "rating" : [ 2, 4 ] }
{ "_id" : ObjectId("5b965d60d5bc80bda9885183"), "email" : "amit11#gmail.com", "rating" : [ 12, 14 ] }
{ "_id" : ObjectId("5b966cf1f12e2344dc5942e5"), "email" : "avin11#gmail.com", "new_rating" : { "id" : [ 5, 6 ] } }
{ "_id" : ObjectId("5b966cfdf12e2344dc5942e6"), "email" : "avin22#gmail.com", "new_rating" : { "id" : [ 2, 4 ] } }
{ "_id" : ObjectId("5b966d06f12e2344dc5942e7"), "email" : "avin33#gmail.com", "new_rating" : { "id" : [ 12, 14 ] } }
{ "_id" : ObjectId("5b986afaf12e2344dc5942e8"), "email" : "Sachin#hotmail.com", "name" : "Sachin" }
Kindly suggest how to perform the search query

Answer 1

Hi and welcome to Stack overflow community..
I think you can still use a regex, but you should have an index on the email field to have better performance.
Read more about regex and indexes on mongo DB here: https://docs.mongodb.com/manual/reference/operator/query/regex/#index-use
I suggest using Explain Results to make sure your query uses the index you added.
Hope this helps.