Simple questions from memcached newbie

[Philip Neustrom]

MySQL cluster is a database designed to hold your data in a
distributed form and happens to use memory for a lot of the indexed
data due to high communication overhead.  The fact it stores a lot of
stuff in memory doesn't make it a terrific caching system or anything
-- at least any more than normal MySQL, which will tend to store
indexs in memory if it can, anyway.  Memcached is just data cache.

On 10/11/06, Just Marc <marc at corky.net> wrote:
> Hi,
>
> Despite what MySQL would want you to think, cluster is very specialized
> and in its current form will probably only fit very, very specific
> apps.   I don't see it being used as a simple "memcached
> replacement".     I also don't think Cluster's performance bottleneck
> (or rather, bottleneck by design) is at the storage backend, so having
> memcache as a storage backend is not likely to improve performance much.
>
> While I don't agree MySQL Cluster is difficult to configure - you simply
> decide on your setup, create a configuration file and copy it over to
> all your nodes, configuration examples exist around so you don't even
> have to do much.   After reading its docs re configuration it shouldn't
> take you more than a few minutes to do so.
>
> If you really want to use it as a memcached replacement, run it in its
> 'diskless' mode so it doesn't write anything to disk on any node,
> everything is then kept in RAM, duplicated, of course.
>
> But from my experience you wouldn't want to go there if you need
> thousands or more queries per second to your cache, if you want to reach
> that kind of performance with cluster you'd have to setup at LEAST a few
> nodes (true, you can setup several nodes per server if they have
> multiple CPUs) but if you need tens of thousands of queries per second
> you'd probably need tens of nodes (or more like 20) and a decent switch
> to push lots of internal traffic between Cluster's nodes (if you have
> lots of writes/updates...).
>
> But as a simple memcache replacement, cluster has significant network
> and other overheads which you may not like, especially in version 5.0
> which is "stable" (but in fact even that version IMHO is not so stable
> nor it is "production grade" -- even if they do run it on many
> production clusters...)
> > On Wed, 2006-10-11 at 15:08 -0500, Andy wrote:
> >
> >> The difference here is that memcached is at least an order of
> >> magnitude
> >> easier to setup and maintain than MySQL cluster, and adding an
> >> additional "storage backend" on memcached means you need to maintain
> >> two
> >> sets of software (memcached and mysql cluster) rather than one (for no
> >> advantage really, since NDB is a memory based store, just like
> >> memcached) resulting in increased complexity.
> >>
> >
> > Thanks Andy for adding in. I totally missed the maintenance part. Apart
> > from performance, memcached is so simple to maintain. Mysql cluster
> > requires too much of configuration!
> >
> >
> > Jeetu
> >
> >
> >
>
>