zlacker

>>hyzyla+(OP)
You really don't need anything fancy to implement a queue using SQL. You need a table with a primary id and a "status" field. An "expired" field can be used instead of the "status". We used the latter because it allows easy retries.

1. SELECT item_id WHERE expire = 0. If this is empty, no items are available.

2. UPDATE SET expire = some_future_time WHERE item_id = $selected_item_id AND expire = 0. Then check whether UPDATE affected any rows. If it did, item_id is yours. If not, loop. If the database has a sane optimizer it'll note at most one document needs locking as the primary id is given.

All this needs is a very weak property: document level atomic UPDATE which can return whether it changed anything. (How weak? MongoDB could do that in 2009.)

Source code at https://git.drupalcode.org/project/drupal/-/blob/9.2.x/core/... (We cooked this up for Drupal in 2009 but I am reasonably sure we didn't invent anything new.)

Of course, this is not the fastest job queue there is but it is quite often good enough.

>>_ugfj+z2
A single Rabbit node seems easier than rolling this yourself and doing all the work to test it.

>>jayd16+oQ
But if we always do what's easiest, then we will make a bunch of horrible choices.

Other things that matter, often more than what's easiest:

* Flexibility. If you aren't 100% sure what you'll need, but need something in place today, it can make sense to choose an unopinionated, generic solution.

* Familiarity. Maybe you've never used Rabbit.

* Ops simplicity. Maybe you already have a bunch of postgres deployed. Adding a new type of system means you need new ways of monitoring, new dependencies, different deployment.