Great article Denis and got more from it, so the final answer is memcache can't handle consistency between clusters as you said.
But this only in case I use multi memcached server, but if only one memcached server, I would not care about consistency, right? On Saturday, 18 October 2014 07:49:37 UTC+2, Denis Samoylov wrote: > > memcached is not a clustered solution, so each server is completely > independent. if you need to keep consistency you need to do this by using > client. great example is Facebook McRouter: > https://code.facebook.com/posts/296442737213493/introducing-mcrouter-a-memcached-protocol-router-for-scaling-memcached-deployments/ > it allows to setup show copy. > > also, keep in mind if you do not use "leases" memcached is pretty > "evential" consistency solution. > > Other option is to use Redis instead of Memcached, it has replication (and > some other advanced features). But replication brings tons of other > problems (especially in a way how it is implemented in Redis) > > > > > On Friday, October 17, 2014 11:23:45 AM UTC-7, Karim Tawfik wrote: >> >> Hi, >> >> I am new to memcached, and try to introduce it on our company as a >> caching layer, but there is a question came up to my mind, how memcached >> handle the consistency of data to all are the same in all clusters. >> >> For example: >> say I have 2 clusters, each have memcached is installed on it, and >> clients started to send requests (e.g.updating some data), how the other >> memcached server would know about such update if it is already caching an >> old version before it got updated. >> >> I am asking this question as i read 2 contradicting statements on the >> website, which are: >> >> 1. Under ==> https://code.google.com/p/memcached/wiki/NewOverview, >> section. >> - Servers are Disconnected From Each Other : Memcached servers are >> generally unaware of each other. There is no crosstalk, no >> syncronization, >> no broadcasting >> 2. Under ==> >> https://code.google.com/p/memcached/wiki/TutorialCachingStory >> - >> >> So again, he takes keys that the Programmer uses and looks for >> them on his memcached servers. 'get this_key' 'get that_key' But each >> time >> he does this, he only finds each key on one memcached! Now WHY would >> you do >> this, he thinks? And he puzzles all night. That's silly! Don't you >> want the >> keys to be on all memcacheds? >> >> "But wait", he thinks "I gave each memcached 1 gigabyte of memory, >> and that means, in total, I can cache three gigabytes of my database, >> instead of just ONE! Oh man, this is great," he thinks. "This'll save >> me a >> ton of cash. Brad Fitzpatrick, I love your ass!" >> >> Could you please give me the clear directions, if i have incorrect view. >> >> The last thing is, does memcached get affected by anymeans of >> replications between server? >> >> Thanks, >> Karim >> > -- --- You received this message because you are subscribed to the Google Groups "memcached" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
