Exploring the Postgres Internals: A Guide for Database Admins and System Developers (Part 1)
Tags: postgres, database, apacheage
Published: 2023-02-25 20:03:58

Postgres is an open-source object-relational database system. It is highly extensible, reliable, and capable of handling large volumes of data. As a powerful database management system, Postgres offers a variety of features, such as advanced query optimization, advanced transaction control, and full-text search capabilities.
To get the most out of Postgres, system developers and database administrators need to have a thorough understanding of its internals. In this guide, we'll provide an overview of Postgres internals and explore the various components and features of the system.

## What are Postgres Internals?
Postgres internals are the various components of Postgres that make up the database system. These components are responsible for the efficient storage and retrieval of data, as well as the security and integrity of the system. They include the storage system, the query optimizer, the transaction manager, and the system catalogs and tables.
The internals of Postgres are highly customizable and can be extended to fit the needs of any application or system. This makes Postgres an ideal choice for developers and administrators who need a powerful, robust, and extensible database system.

## Benefits of Understanding Postgres Internals
Having a thorough understanding of Postgres internals has several benefits for system developers and database administrators. Firstly, it enables them to customize the system to their specific needs and make it more efficient. Secondly, it allows them to optimize the performance of their applications by understanding how the various components interact with each other.
Finally, understanding the internals of Postgres gives system developers and database administrators greater control over the security and integrity of their system. By understanding how the various components work together, they can ensure that the system is secure and that data is protected from malicious actors.

## Overview of Postgres Architecture
Postgres is an object-relational database system that is built on an extensible architecture. It is composed of several components, such as the **query optimizer**, the **storage system**, the **transaction manager**, and the **system catalogs and tables**.
The query optimizer is responsible for optimizing queries and ensuring that they run as efficiently as possible. The storage system is responsible for storing and retrieving data from the database. The transaction manager is responsible for managing transactions and ensuring that they are atomic, consistent, and isolated. Finally, the system catalogs and tables are responsible for maintaining the data dictionary, which stores information about the structure of the database.

## Postgres Storage System
The Postgres storage system is responsible for storing and retrieving data from the database. It consists of several components, such as the data files, the WAL (Write-Ahead Logging) files, and the system catalogs. The data files are the actual files that contain the data, while the WAL files are used for crash recovery and are written to before any changes are made to the data files. The system catalogs are responsible for storing information about the structure of the database, such as the tables and indexes.
The Postgres storage system is highly customizable, allowing system developers and database administrators to adjust the configuration to their specific needs. For example, they can adjust the size of the data files, the size of the WAL files, and the number of system catalogs.

## Postgres System Catalogs and Tables
The system catalogs are responsible for maintaining the data dictionary, which stores information about the structure of the database. The system catalogs contain information about the tables, indexes, and other objects in the database. They are used by the query optimizer to optimize queries and by the transaction manager to ensure the integrity of the system.
The system catalogs also contain information about the data types and constraints of the tables, such as the data types of the columns, the primary and foreign keys, and the indexes. This information is used by the query optimizer to optimize queries and by the transaction manager to ensure the integrity of the system.

References: [https://www.interdb.jp/pg/index.html](https://www.interdb.jp/pg/index.html)

If you are interested in graph databases, do explore [**Apache AGE®**](https://age.apache.org/)!!!!