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Questions - mongodb-indexes

Is it efficient to store sha256 hash of username in _id field in MongoDB?

I have a special need to hash the username, and also I need to keep the usernames unique for my purpose. So, my question is can I override default '_id' field of mongoDB with sha256 hash of username? ...
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Prithvi Reddy

python

mongodb

mongodb-indexes

Votes: 0

Answers: 1

Latest Answer

Technically, there is no problem with using sha256 for the value of _id. The default ObjectId type in MongoDB is convenient for creating a unique value "on the spot" but not required. The ...
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Buzz Moschetti

What if some documents don't have a field that is part of an index?

A collection has an indexed involved field_A. But field_A is not required. So what happens if some documents do not have this field? Will the index still work for documents that do have this field?
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Bear Bile Farming is Torture

node.js

mongodb

mongodb-query

nosql

mongodb-indexes

Votes: 0

Answers: 2

Latest Answer

Yes it works, here is a test: db.collection.createIndex({ field_A: 1 }); for (let i = 0; i < 100; i++) db.collection.insertOne({ field_B: i }); db.collection.stats(1024).indexSizes { "_i...
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Wernfried Domscheit

Which query faster on MongoDB with two index

I have two index in mongodb. First index field is "string" and second index field is "date". String field is partial. Why faster than I query "string" with "date&quo...
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Murat Aslan

mongodb

mongodb-query

mongodb-indexes

Votes: 0

Answers: 1

Latest Answer

I was using separately. As @R2D2 said: db.mycollection.createIndex({fruit: 1,date:-1},{partialFilterExpression:{fruit:{$exists: true }}}); Using that method has made it much faster. Also indexes size ...
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Murat Aslan

MongoDB TTL index never deletes records

I created an index as shown below and added a createdAt field to each new record added to the db. The records should be auto-deleted after 24 hours however I have waited days and nothing has been dele...
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Amber Johnson

javascript

mongodb

ttl

database-indexes

mongodb-indexes

Votes: 0

Answers: 1

Latest Answer

Expiration of data requires that the indexed field value be a BSON date, or an array of BSON dates. MongoDB Reference Manual Expiration of Data TTL indexes expire documents after the specified number ...
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rickhg12hs

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