Get the latest tech news

Careful with That Lock, Eugene

It is rewarding to work on software that people care about and use all around the clock. This constant usage means we can't simply take the system offline for maintenance without upsetting users. Therefore, techniques that allow us to update the software seamlessly without downtime or compromising service quality are …

This constant usage means we can't simply take the system offline for maintenance without upsetting users. They will want to apply a simple, and seemingly innocent migration, like adding a column to a table and it'll cause some number of requests to fail, or maybe even a small outage. This scenario is essentially identical to one in which there's a single migration statement that requires an AccessExclusiveLock and performs a table rewrite, such as adding a NOT NULL column with a DEFAULT value.

Get the Android app