Re: Future direction for the row cache and OHC implementation

2023-12-20 Thread German Eichberger via dev
Hi, we once did some extensive performance testing on the row cache (motivated by some hardware accelerator we were hoping to introduce) but could only find improvements in highly contrived scenarios - has been a while since then so fresh eyes are good but I think we will still arrive at the c

Re: [DISCUSS] CEP-39: Cost Based Optimizer

2023-12-20 Thread Benjamin Lerer
> > Pick a random replica and ask it to prepare it, and use that. This is > probably fine, unless there is significant skew (in which case, our plan is > likely to bad whatever, somewhere) To be sure that I understand you correctly. What you are suggesting is to use local statistics to compute th

Re: [DISCUSS] CEP-39: Cost Based Optimizer

2023-12-20 Thread C. Scott Andreas
Thanks for this proposal and apologies for my delayed engagement during the Cassandra Summit last week. Benjamin, I appreciate your work on this and your engagement on this thread – I know it’s a lot of discussion to field.On ALLOW FILTERING:I share Chris Lohfink’s experience in operating clusters

Re: [DISCUSS] CEP-39: Cost Based Optimizer

2023-12-20 Thread C. Scott Andreas
Thanks for this proposal and apologies for my delayed engagement during the Cassandra Summit last week. Benjamin, I appreciate your work on this and your engagement on this thread – I know it’s a lot of discussion to field. On ALLOW FILTERING: I share Chris Lohfink’s experience in operating clust

Re: [DISCUSS] CEP-39: Cost Based Optimizer

2023-12-20 Thread Benedict
I see three options:Pick a random replica and ask it to prepare it, and use that. This is probably fine, unless there is significant skew (in which case, our plan is likely to bad whatever, somewhere)If there already exists a plan for the query, return thatPick a sample of replicas and eitherAsk th

Re: [DISCUSS] CEP-39: Cost Based Optimizer

2023-12-20 Thread Benjamin Lerer
> > If we are to address that within the CEP itself then we should discuss it > here, as I would like to fully understand the approach as well as how it > relates to consistency of execution and the idea of triggering > re-optimisation. Sure, that was my plan. I’m not sold on the proposed set of

Re: [DISCUSS] CEP-39: Cost Based Optimizer

2023-12-20 Thread Benedict
If we are to address that within the CEP itself then we should discuss it here, as I would like to fully understand the approach as well as how it relates to consistency of execution and the idea of triggering re-optimisation. These ideas are all interrelated.I’m not sold on the proposed set of cha

Re: [DISCUSS] CEP-39: Cost Based Optimizer

2023-12-20 Thread Benjamin Lerer
After the second phase of the CEP, we will have two optimizer implementations. One will be similar to what we have today and the other one will be the CBO. As those implementations will be behind the new Optimizer API interfaces they will both have support for EXPLAIN and they will both benefit fro