I think the general approach is to denormalise data to remove the need for complicated semantics when reading.
Aaron On 19/01/2011, at 7:57 AM, Shu Zhang <szh...@mediosystems.com> wrote: > Well, maybe making a batch-get is not anymore efficient on the server side > but without it, you can get bottlenecked on client-server connections and > client resources. If the number of requests you want to batch is on the order > of connections in your pool, then yes, making gets in parallel is as good or > maybe better. But what if you want to batch thousands of requests? > > The server I can scale out, I would want to get my requests there without > needing to wait for connections on my client to free up. > > I just don't really understand the reasoning for designing muliget_slice the > way it is. I still think if you're gonna have a batch-get request > (multiget_slice), you should be able to add to the batch a reasonable number > of ANY corresponding non-batch get requests. And you can't do that... Plus, > it's not symmetrical to the batch-mutate. Is there a good reason for that? > ________________________________________ > From: Brandon Williams [dri...@gmail.com] > Sent: Monday, January 17, 2011 5:09 PM > To: user@cassandra.apache.org > Cc: hector-us...@googlegroups.com > Subject: Re: please help with multiget > > On Mon, Jan 17, 2011 at 6:53 PM, Shu Zhang > <szh...@mediosystems.com<mailto:szh...@mediosystems.com>> wrote: > Here's the method declaration for quick reference: > map<string,list<ColumnOrSuperColumn>> multiget_slice(string keyspace, > list<string> keys, ColumnParent column_parent, SlicePredicate predicate, > ConsistencyLevel consistency_level) > > It looks like you must have the same SlicePredicate for every key in your > batch retrieval, so what are you suppose to do when you need to retrieve > different columns for different keys? > > Issue multiple gets in parallel yourself. Keep in mind that multiget is not > an optimization, in fact, it can work against you when one key exceeds the > rpc timeout, because you get nothing back. > > -Brandon
