Getting multiple hashes from redis using StackExchange.Redis

Question

I need get about 10k hashes from redis server. Since there is no command to get multiple hashes in redis I was iterating through the all keys using db.HashGetAllAsync() call and then waiting all tasks to complete. Even though it worked I saw a dramatic latency spike on RedisLabs dashboard during these calls.

Is there any ways to get many hashes at the same time? Maybe there is any ConnectionMultiplexer settings that may help in this situation?

Are you running multiple invocations of this call, then awaiting all of the results to be returned? If so, how many concurrent connections are you running? — The Real Bill
– The Real Bill, Commented Mar 18, 2015 at 0:32

Marc Gravell · Accepted Answer · 2015-03-17 13:14:36Z

3

There is no varadic hgetall, so yes: the simplest approach would be to pipeline a huge number of individual hgetall. The only other thing you could even possibly do would be to use a Lua script (eval/evalsha) to generate multiple items in each item, but I can't see how this would reduce server load or bandwidth any, so it doesn't seem to be worth trying!

Either way, yes: this will generate some work on the server.

answered Mar 17, 2015 at 13:14

Marc Gravell

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2 Comments

pauliusnrk Over a year ago

I guess using Lua script in situation where I'm trying to get 10k hashes would put other redis calls to queue and increase latency even more.

Marc Gravell Over a year ago

@pauliusnrk yep, I'd guess so too; your best bet here, IMO, would be to do the bulk hash read from a slave

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