Add an option to disable MGET splitting in Redis (to avoid performance penalty)

[hedgesky]

Hello 👋
I have a question regarding splitting Redis MGET commands into multiple GET ones (implemented here). Would it be possible to add a configuration option to disable this behavior?

Let me describe the use case. We're adding Envoy as a proxy to a Redis Cluster. Our app sends MGET requests with dozens of keys like {my_user_id}:key1, {my_user_id}:key2, etc. As the user id is the same in all the keys, all of them are guaranteed to be hashed to the same slot.

With a regular Redis Cluster, only one command is executed (the MGET one). With Envoy, however, the MGET is split into N separate GET requests, which incurs a noticeable performance hit. Having an option to disable splitting would allow us to avoid that penalty.
UPD. A similar issue seems to apply to DEL, EXISTS, TOUCH, and UNLINK commands (source).

Relevant links:

• This performance issue was also mentioned in Our journey switching from twemproxy to Envoy Redis Proxy (and some perf issues) #19436 (comment)
• The implementation of MGET splitting in Envoy
• Redis MGET command documentation

[zuercher]

cc @weisisea @mattklein123

[deveshkandpal1224]

I think this would also benefit this github issue ( not splitting the MGET request to individual GET request ) -> #31038.

[github-actions]

This issue has been automatically marked as stale because it has not had activity in the last 30 days. It will be closed in the next 7 days unless it is tagged "help wanted" or "no stalebot" or other activity occurs. Thank you for your contributions.

[weisisea]

This makes sense. One idea is that for a multi-key command, we can calculate the hash of the keys and send the command without splitting to the target Redis node if all the key hashes are the same.

[weisisea]

@zuercher could you please advise on how to add the label "help-wanted"? It seems that I wasn't able to find a way to add the label. Thanks!

[weisisea]

/help

[github-actions]

This issue has been automatically marked as stale because it has not had activity in the last 30 days. It will be closed in the next 7 days unless it is tagged "help wanted" or "no stalebot" or other activity occurs. Thank you for your contributions.

[github-actions]

This issue has been automatically closed because it has not had activity in the last 37 days. If this issue is still valid, please ping a maintainer and ask them to label it as "help wanted" or "no stalebot". Thank you for your contributions.