Postgres Internal Architecture Explained

Hussein Nasser・2 minutes read

Postgres architecture focuses on processes for various tasks, with shared memory and background workers enhancing scalability. Background processes like the writer and checkpointer manage database operations and ensure consistency and recovery, essential for stable performance and durability.

Insights

  • Postgres architecture prioritizes processes for handling various tasks like IO, maintenance, and auxiliary functions, enhancing system stability and performance.
  • Shared memory, managed by shared buffers, plays a crucial role in storing data accessible to all processes, emphasizing the significance of efficient memory management in Postgres for optimal operation and scalability.

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Recent questions

  • What is the main process in Postgres architecture?

    The main process in Postgres architecture is the postmaster, which functions as the listener for connections on Port 5432.

  • How do background workers enhance Postgres scalability?

    Background workers in Postgres execute queries in parallel, improving scalability and predictability within the system.

  • What is the role of shared memory in Postgres?

    Shared memory, known as shared buffers in Postgres, stores data and is accessed by all processes, playing a crucial role in system performance.

  • How does the background writer optimize disk writes in Postgres?

    The background writer in Postgres flushes pages to the OS, not directly to disk, to optimize disk writes and reduce wear on SSDs, enhancing efficiency.

  • Why is the wall archiver important in Postgres architecture?

    The wall archiver in Postgres backs up wall entries crucial for recovery and replication, serving as the DNA of the database to ensure data consistency and integrity.

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Summary

00:00

"Postgres Architecture: Processes, Memory, Scalability"

  • Postgres architecture focuses on processes handling auxiliary, maintenance, and IO tasks.
  • An architecture diagram detailing Postgres components and their connections is referenced.
  • The main process, postmaster, acts as the listener for connections on Port 5432.
  • Back-end processes in Postgres handle various tasks within the system.
  • Shared memory, known as shared buffers, stores data and is accessed by all processes.
  • Background workers execute queries in parallel, enhancing scalability and predictability.
  • Background processes are limited by the max worker process configuration.
  • Auxiliary processes, like the background writer, assist in managing database operations.
  • Understanding the use of processes over threads in Postgres for stability and performance.
  • The importance of shared memory and the challenges of managing it effectively in Postgres.

18:40

Optimizing Database Performance and Durability

  • Writing to pages and the wall in memory is temporary, needing eventual flushing to disk for durability.
  • Background writer flushes pages to the OS, not directly to disk, to optimize disk writes and reduce wear on SSDs.
  • OS caches writes in memory before flushing to disk to prevent excessive disk writes and maintain SSD lifespan.
  • Background writer's main task is to free up shared memory by flushing dirty pages to disk.
  • Checkpointer flushes all changes to disk, creating a checkpoint for consistency and recovery in case of a crash.
  • Auto vacuum cleans up old tuples to optimize database space and performance.
  • Wall archiver backs up wall entries crucial for recovery and replication, acting as the DNA of the database.
  • Wall sender transmits wall changes to replicas, ensuring data consistency across databases.
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