Posted over 6 years ago. Visible to the public. Repeats. Linked content.

Databases don't order rows unless you tell them so

There is no such thing as a "default order" of rows in database tables.

For instance, when you paginate a result set: When using LIMIT, it is important to use an ORDER BY clause that constrains the result rows into a unique order. Otherwise you will get an unpredictable subset of the query's rows. You might be asking for the tenth through twentieth rows, but tenth through twentieth in what ordering? The ordering is unknown, unless you specified ORDER BY.

In Rails, if you use Record.first or Record.last, it will default to ordering by id.

Your development team has a full backlog of feature requests, chores and refactoring coupled with deadlines? We are familiar with that. With our "DevOps as a Service" offering, we support developer teams with infrastructure and operations expertise.

Owner of this card:

Avatar
Andreas Robecke
Last edit:
almost 3 years ago
by Besprechungs-PC
Keywords:
postgresql
About this deck:
We are makandra and do test-driven, agile Ruby on Rails software development.
License for source code
Posted by Andreas Robecke to makandra dev
This website uses short-lived cookies to improve usability.
Accept or learn more