Cassandra is a database, not an in-memory cache. Please don't abuse Cassandra like that when there's plenty of existing distributed cache products designed for that purpose.
That's like asking "why can't I drag race with a school bus?" You could and it might be fun, but that's not what it was designed for. On Fri, Oct 7, 2016 at 11:22 AM, KARR, DAVID <dk0...@att.com> wrote: > No, I haven’t “thought why people don’t use Cassandra as a cache”, that’s > why I’m asking this here. I’m asking the community for their POV when it > might make sense to front Cassandra with Hazelcast. This is even mentioned > as a use case in the Hazelcast documentation (“As a front layer for a > Cassandra back-end”), and I’m aware of at least one large private > enterprise that does this. > > > > *From:* Dorian Hoxha [mailto:dorian.ho...@gmail.com] > *Sent:* Friday, October 07, 2016 3:48 AM > *To:* user@cassandra.apache.org > *Subject:* Re: Rationale for using Hazelcast in front of Cassandra? > > > > Primary-key select is pretty fast in rdbms too and they also have caches. > By "close to" you mean in latency ? > > Have you thought why people don't use cassandra as a cache ? While it > doesn't have LRU, it has TTL,replicatio,sharding. > > > > On Fri, Oct 7, 2016 at 12:00 AM, KARR, DAVID <dk0...@att.com> wrote: > > Clearly, with “traditional” RDBMSs, you tend to put a cache “close to” the > client. However, I was under the impression that Cassandra nodes could be > positioned “close to” their clients, and Cassandra has its own cache (I > believe), so how effective would it be to put a cache in front of a cache? > > > > *From:* Dorian Hoxha [mailto:dorian.ho...@gmail.com] > *Sent:* Thursday, October 06, 2016 2:52 PM > *To:* user@cassandra.apache.org > *Subject:* Re: Rationale for using Hazelcast in front of Cassandra? > > > > Maybe when you can have very hot keys that can give trouble to your > 3(replication) cassandra nodes ? > > Example: why does facebook use memcache ? They certainly have things > distributed on thousands of servers. > > > > On Thu, Oct 6, 2016 at 11:40 PM, KARR, DAVID <dk0...@att.com> wrote: > > I've seen use cases that briefly describe using Hazelcast as a "front-end" > for Cassandra, perhaps as a cache. This seems counterintuitive to me. Can > someone describe to me when this kind of architecture might make sense? > > > > >
