Question 9:
Imagine an electronic medical record database designed to hold the medical records of every individual in the United States. Because each person has more than 16MB of medical history and records, it's not feasible to have a single document for every patient. Instead, there is a patient collection that contains basic information on each person and maps the person to a patient_id, and a record collection that contains one document for each test or procedure. One patient may have dozens or even hundreds of documents in the record collection.
We need to decide on a shard key to shard the record collection. What's the best shard key for the record collection, provided that we are willing to run inefficient scatter-gather operations to do infrequent research and run studies on various diseases and cohorts? That is, think mostly about the operational aspects of such a system. And by operational, we mean, think about what the most common operations that this systems needs to perform day in and day out.
Options:
Answer is patient_id
Imagine an electronic medical record database designed to hold the medical records of every individual in the United States. Because each person has more than 16MB of medical history and records, it's not feasible to have a single document for every patient. Instead, there is a patient collection that contains basic information on each person and maps the person to a patient_id, and a record collection that contains one document for each test or procedure. One patient may have dozens or even hundreds of documents in the record collection.
We need to decide on a shard key to shard the record collection. What's the best shard key for the record collection, provided that we are willing to run inefficient scatter-gather operations to do infrequent research and run studies on various diseases and cohorts? That is, think mostly about the operational aspects of such a system. And by operational, we mean, think about what the most common operations that this systems needs to perform day in and day out.
Options:
- patient_id
- _id
- Primary care physician (your principal doctor that handles everyday problems)
- Date and time when medical record was created
- Patient first name
- Patient last name
Answer is patient_id
I don't agree, because patient_id will cause hotspotting.
ReplyDeleteYes even I got the same hotspotting doubt. but, no other option seems to exactly correct. If its a multi choice I will go with patient first name and Patient last name. But, now its a single option question and I am confused
ReplyDelete"there is a patient collection that contains basic information on each person and maps the person to a patient_id, and a record collection that contains one document for each test or procedure."
ReplyDeleteMaybe patient_id is some kind of hash function which won't cause hotspotting.