A Vacuum Riddle: What's Socks but Doesn't Suck? 

A vacuum!

(Except for the Postgres vacuum, which does—occasionally—suck.)

A Common Problem: Misconfigured PostgreSQL Vacuum

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It’s a topic that’s been discussed time and time again, yet I still see PostgreSQL databases struggling with poorly configured vacuum processes. If you’ve ever had to troubleshoot a database performance issue, you’re probably familiar with the frustration. So, as a service to the public (and to help you get home earlier to your wife and kids—or your PlayStation), here are some basic rules for configuring your vacuum process properly.

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Rule #1: Never Disable the Vacuum Process

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The vacuum process does exactly what its name implies—it vacuums up old data that’s no longer needed. But let’s break it down further:
When you delete a row from a table:
DELETE FROM mytable WHERE id=1;
The row is not immediately removed from the table’s data block. Instead, it’s marked as deleted, leaving behind a "dead row" that will be cleaned up later by the vacuum process.

The same applies to updates:
UPDATE mytable SET salary=salary-100 WHERE name='Robert';
In this case, the old salary for Robert is still there, marked as dead, but waiting to be cleaned up by VACUUM. Now imagine that Robert’s salary is updated 1,000 times (yes, poor Robert’s salary is negative by now, but let’s assume he still loves his job). If VACUUM is disabled, there will be 1,000 dead rows for each update, and only one live row.

What does this mean? Your table will become bloated, consuming more space, and performance will suffer because full table scans and index scans will have to process many unnecessary dead rows to find the live data.
Moral of the story? Never, ever disable the vacuum process. It’s critical for maintaining your database’s health and performance.

In the next chapter, we will discuss how to monitor the vacuum process effectively and dive into some additional best practices for keeping your PostgreSQL vacuum process in check.

Cluster Spotlight

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Your go-to source for all things 123cluster: platform news, step-by-step tutorials, and can’t-miss community events. Whether you’re spinning up a new cluster or fine-tuning an existing one, these resources will empower your workflow and spark new ideas.