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We are using mongo db to store certain records in production database.
We see our records having "_id" : { "$oid" : "50585fbcb046b2709a534502"} in production database , while we see same record as "_id" : ObjectId(" 50585fbcb046b2709a534502 ") in the qa database.
For dates we see "ld" : { "$date" : "2011-12-03T17:00:00Z"} in prod database, while "ld" :ISODate("2011-12-03T17:00:00Z") in qa database.
We have tested our queries successfully in qa environment, but worried it might fail in production
1) Will my java queries work seamlessly on prod & qa both? (I am using morphia apis to query) 2) Are they internally being stored in the same identical way?
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The _id field is the default field for Bson ObjectId's and it is,by default, indexed. _id and id are not the same. You may also choose to add a field called id if you want, but it will not be index unless you add an index. It is just a typo in the docs.
From the documentation: Mongoose assigns each of your schemas an id virtual getter by default which returns the documents _id field cast to a string, or in the case of ObjectIds, its hexString.
_id is the primary key on elements in a collection; with it, records can be differentiated by default. _id is automatically indexed. Lookups specifying { _id: <someval> } refer to the _id index as their guide. Users can also override _id to something other than an ObjectID data type, if desired.
You should NOT convert the ObjectId in the database to a string, and then compare it to another string. If you'd do this, MongoDB cannot use the _id index and it'll have to scan all the documents, resulting in poor query performance.
To answer the two questions:
ObjectId and ISODate (normally) whereas picking it out directly from the server language (Java in your case) will tend to show the full objects properties ($oid and $date in this case).
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