[antirez]

Hello Simon,

sending LPUSH+LTRIM in a pipeline is the same as having a special command for this. But having a special command for this, and for other use cases, makes Redis somewhat less general. What I mean is that if we consider every added feature a cost (complexity cost, not development cost), why don't instead add a feature that allows for a use case currently not covered?

Btw there is an interesting pattern so you actually need to rarely send the LTRIM. Imagine this: you want a list to save the user timeline, you are interested only in the latest 100 messages. So for every entry you can LPUSH+LTRIM. But after all you can just LTRIM 10% of the times. Your list will fluctuate in length between 100 and 110, but as you access things using LRANGE the additional elements wil not create any problem. So the cost of the LTRIM, while already very very small, can be made 90% smaller with this simple trick.

[conorh]

I use this exact pattern at Boxcar to keep some lists short and it works great for us.

[antirez]

Thank you for reporting a "live" usage of this pattern!