✅ Clean Code code with better readability method naming no error no repetition dependency ❌ one function per one class/method adequate spacing between functions Naming...

✅ Stored Procedure run several queries as if it is one function 👍🏻 optimization, cache easy to update less traffic between client and server with SQL security 👎🏻 less compatib...

✅ Redis normally, DB is saved on harddisk or SSD 👍🏻 Redis is saved on RAM, very fast If redis is saved on RAM, isnt RAM volatile? need backup to prevent snapshot: ba...

✅ Transaction work unit for updating database atomacity: 반영되거나, 반영되지 않거나 consistency isolation: when one transaction is working, another transaction cannot interfere durability:...

✅ DB Index to search faster in RDMS enhance query speed 👍🏻 data search faster 👍🏻 data sort faster 👍🏻 data update faster 👍🏻 efficient management of data ✔️ index a column in table...

✅ Anomaly 이상 현상 테이블을 잘못 설계하여 데이터 삽입, 삭제, 수정할 때 오류 발생 > 1. Insertion Anomaly need to add unnecessary data to instert when is primary key, if need to save students who did not...

✅ SQL Injection Malicious SQL by a hacker to be transmitted to DB, attacking the data 😈 SQL Injection Attack Delete data attack when user logs in, inputs ID and password hacker wou...

✅ Key identify the tuples(rows) uniquely in the table 🔑 Candidate Key minimal set to uniquely identify a tuple every table must have at least single candidate key can have multiple candid...

✅ Blocking/Non Blocking ⭐️ control calling method hands control over to called method 제어권을 넘겨주는가? ✔️ Blocking 제어권을 넘겨준다. calling process needs to wait for called process to ...

✅ Load Balancing sharing the work(load) to more than two servers network connection ⬆️ scale-up: increase capability of hardware scale-out: divide work among several servers ➡️ Load bal...