For Part 1 follow this link.

Postgres Indexes and Query Optimization

Postgres indexes are used to improve the performance of queries. They are used by the query optimizer to optimize queries and by the transaction manager to ensure the integrity of the system. Indexes are created on columns in tables and are used to quickly retrieve data from the table. Postgres supports several types of indexes, including B-tree, hash, and GiST indexes.
The query optimizer is responsible for optimizing queries and ensuring that they run as efficiently as possible. It uses several techniques, such as index optimization, join optimization, and query rewriting, to optimize queries. It also uses the system catalogs to determine the best execution plan for each query.

Postgres Transaction Management

Postgres transactions are used to ensure the integrity and consistency of the data in the database. They are atomic, consistent, isolated, and durable (ACID). The transaction manager is responsible for managing transactions and ensuring that they are atomic, consistent, and isolated. It also ensures that the changes made by each transaction are durable and can be recovered in the event of a crash.
The transaction manager uses several techniques, such as locking, logging, and two-phase commit, to ensure that transactions are atomic, consistent, and isolated. It also uses the system catalogs to determine the best execution plan for each transaction.

Postgres Autovacuum and Performance Tuning

Postgres autovacuum is a process that is responsible for reclaiming disk space and maintaining the performance of the system. It is used to automatically analyze and vacuum tables, indexes, and other objects in the system. Autovacuum is used to reclaim disk space and maintain the performance of the system by removing unused data and preventing the system from becoming fragmented.
Postgres performance tuning is the process of optimizing the performance of the system. It is used to analyze the system and identify areas that can be improved. Performance tuning is used to optimize the query optimizer, the storage system, the transaction manager, and the system catalogs and tables.

Postgres Security and Data Encryption

Postgres security is used to protect the system from malicious actors. It is used to protect the system from unauthorized access, data tampering, and other malicious activities. Postgres provides several features to ensure the security of the system, such as authentication, authorization, and encryption.
Postgres data encryption is used to protect data from unauthorized access. It is used to encrypt data before it is stored in the database and to decrypt it when it is retrieved. Postgres supports several encryption algorithms, such as AES, RSA, and SHA.

Conclusion

In this guide, we provided an overview of Postgres internals and explored the various components and features of the system. We discussed the benefits of understanding Postgres internals and explored the various components, such as the query optimizer, the storage system, the transaction manager, and the system catalogs and tables.
We also discussed Postgres indexes, query optimization, transaction management, autovacuum, and performance tuning. Finally, we discussed Postgres security and data encryption.
Understanding the internals of Postgres is essential for system developers and database administrators. It enables them to customize the system to their specific needs and optimize the performance of their applications. It also gives them greater control over the security and integrity of their system.

References: https://www.interdb.jp/pg/index.html

If you are interested in graph databases, do explore Apache AGE®!!!!