Understanding Background Processes in PostgreSQL
Tags: postgres, postgressql, database
Published: 2023-08-12 15:06:24


When PostgreSQL starts, many background tasks are made by the main server, also known as the "postmaster" process. These processes perform a variety of functions that are crucial to the database's seamless and effective operation. These background operations usually have a distinct function. This article delves into the specifics of these procedures and clarifies why they are crucial.

####1. 	Essential Background Processes:

**Checkpointer:**

Among the paramount operations, the checkpointer guarantees that alterations performed in the memory (buffer cache) are inscribed (flushed) onto the disk at regular intervals. By executing this in the backdrop at planned periods, it secures that the system need not write all elements simultaneously during crash recovery.

**Writer:**

This procedure writes buffer pages onto the disk in advance of their necessity, aiding in diminishing the count of buffers that necessitate inscription by the checkpointer or backends.

**WAL Writer:**

This process flushes the write-ahead log (WAL) buffers onto the disk. The Log maintains a chronicle of all modifications made to the database, permitting crash recovery.

**Stats Collector:**

This process assembles information concerning database activity. It accumulates information such as access to tables and indexes, along with the inner movement of the system. This data facilitates DBAs (Database Administrators) in fine-tuning performance.

**Archival Supervisor:**

In case archiving of antiquated sections of WAL, logs is active, this process oversees that responsibility. Archiving is pivotal for recovery at specific time points and particular duplication setups.

**Vacuum:**

This process clears up and repossesses storage. As time progresses and data undergoes updates or deletions, the database collects 'dead rows.' The vacuum process eradicates these, ensuring practical usage of space and continued peak performance. AutoVacuum automates this task, executing the vacuum process as required.

**WAL Sender and Receiver:**

These processes come into action when replication is configured. The WAL Sender process sends WAL records to standby servers, while the WAL receiver process on the standby server receives and writes those records.
 
###2. 	Impact of Background processes on performance:
 
The simultaneous operation of these procedures guarantees the seamless functioning of PostgreSQL:
 
- By delegating routine maintenance and data security tasks to these processes, the central server process remains free to manage incoming client connections and queries.
- Operations like log writing, archiving, or buffer flushing to the disk can bring time lag if executed synchronously. By overseeing these tasks in the background, PostgreSQL can sustain optimal performance and responsiveness.
- Procedures like AutoVacuum are imperative to ensure the database doesn't become overburdened with repeated data and maintains efficient utilization of storage space.

###4.   Conclusion:

For any database administrator or developer, comprehending the background processes in PostgreSQL holds prime importance. These procedures guarantee that the database retains its responsiveness, security, and efficiency. By digging in into each process’s depths, one can optimize configurations, fine-tune performance, and assure the system's availability and resilience.
For those delving into PostgreSQL, acknowledging these inconspicuous processes in the background can offer important insights into the elaborate and robust architecture of this renowned RDBMS.