[redis-db] Maximum limit on value size in Redis

[preetika tyagi]

Hi all,

I have a general question on the maximum limit on the size of values in
Redis. Currently, 512mb is the maximum limit allowed by Redis, which can be
configured to use a different (smaller than 512mb) max limit.
However, Redis is also used as cache a lot of times and I was wondering if
512mb is quite a big size to reside in cache. Does anyone know by
experience what the usual maximum size of values is in real world
applications using Redis?

Thanks,
Preetika

[Geoffrey Hoffman]

I think you’d be hard pressed to find a good answer to this question, because Redis data types vary wildly and use cases do too.

We have some cached query results that are a couple of megabytes, but most our keys store a single integer (counts). For the vast majority of our data, the key takes up more memory than the value its storing! Example

GET abc:123:def:456:ghi:789:y:2018:m:11:d:15:h:18 // returns 4927

In other cases the key is all we need - there is no data at all, the logic our application relies on is a key hit or miss - there’s no value in the key. Just the presence of the key or not.

I think if you are actually storing close to 512mb in a single key, I can’t imagine what that would be used for. If it’s a static content asset source, a CDN is a better choice.

Post by preetika tyagi
Hi all,
I have a general question on the maximum limit on the size of values in Redis. Currently, 512mb is the maximum limit allowed by Redis, which can be configured to use a different (smaller than 512mb) max limit.
However, Redis is also used as cache a lot of times and I was wondering if 512mb is quite a big size to reside in cache. Does anyone know by experience what the usual maximum size of values is in real world applications using Redis?
Thanks,
Preetika

[preetika tyagi]

@phpguru
Thank you for details. It was helpful.
Preetika

I think you’d be hard pressed to find a good answer to this question,
because Redis data types vary wildly and use cases do too.
We have some cached query results that are a couple of megabytes, but most
our keys store a single integer (counts). For the vast majority of our
data, the key takes up more memory than the value its storing! Example
GET abc:123:def:456:ghi:789:y:2018:m:11:d:15:h:18 // returns 4927
In other cases the key is all we need - there is no data at all, the logic
our application relies on is a key hit or miss - there’s no value in the
key. Just the presence of the key or not.
I think if you are actually storing close to 512mb in a single key, I
can’t imagine what that would be used for. If it’s a static content asset
source, a CDN is a better choice.

Post by preetika tyagi
Hi all,
I have a general question on the maximum limit on the size of values in

Redis. Currently, 512mb is the maximum limit allowed by Redis, which can be
configured to use a different (smaller than 512mb) max limit.

Post by preetika tyagi
However, Redis is also used as cache a lot of times and I was wondering

if 512mb is quite a big size to reside in cache. Does anyone know by
experience what the usual maximum size of values is in real world
applications using Redis?

Post by preetika tyagi
Thanks,
Preetika