The author builds complexity of the databases step by step. Each step has detailed explanations, code, benchmarks and tradeoff decisions that are being talked through. Some of the topics include
Persisting records and indices on disk for both read-only and read/write databases (LSM trees)
Write ahead logs for durability
Managing concurrent operations through different locking approaches
Your care providers might change, the doctors you visit will change over time and the problems you face will change too. Need to keep track of all these moving parts.
In the US, simply request copies of your medical records from your health care providers. Typically, it takes a few days and they get mailed. Copying and sending medical records is a normal part of a health care providers business because that's how health care providers communicate about patients.
As an aside, contemporary best practice seems to be to provide treatment and test results to patients at the office visit. It tends to save everyone time. It's not a red flag if your providers don't do that, but information hording may be symptomatic of a paternalistic view of the doctor-patient relationship since there's nothing to be gained from withholding the record and no benefit for the patient. It would make me wonder what other modern approaches the health care provider doesn't know about or eschews.
Most test results are undecipherable to 99% of people, and the names and number ranges most likely will scare most people if they are out of bounds without explanation.
That and individual tests do not give an accurate picture without knowing about you healthy history, which is something your doctor does.
Usually, the patient knows the most about their health history. The meaning of test results should be explained by the patient's health care provider until the patient understands. It is likely that anyone interested enough to request a copy of their medical records is also interested enough to Google for more information. In the worst case, the patient is as uninformed with the records as without. Out in the real world, it is not uncommon for a doctor to only make a cursory review of a patient's chart before entering the exam room and for the patient to have to verbally provide basic and important information about their health history.
Providing information is what doctor's do. Good doctor's focus on the patient making an informed decision. Witholding information is contrary to that good practice.
Persisting records and indices on disk for both read-only and read/write databases (LSM trees)
Write ahead logs for durability
Managing concurrent operations through different locking approaches