correct - I see also no other solution for this problem On Thu, Mar 29, 2012 at 1:46 AM, Guy Incognito <dnd1...@gmail.com> wrote:
> well, no. my assumption is that he knows what the 5 itemTypes (or > appropriate corresponding ids) are, so he can do a known 5-rowkey lookup. > if he does not know, then agreed, my proposal is not a great fit. > > could do (as originally suggested) > > userId -> itemType:activityId > > if you want to keep everything in the same row (again assumes that you > know what the itemTypes are). but then you can't really do a multiget, you > have to do 5 separate slice queries, one for each item type. > > can also do some wacky stuff around maintaining a row that explicitly only > holds the last 10 items by itemType (meaning you have to delete the oldest > one everytime you insert a new one), but that prolly requires read-on-write > etc and is a lot messier. and you will prolly need to worry about the case > where you (transiently) have more than 10 'latest' items for a single > itemType. > > On 28/03/2012 09:49, Maciej Miklas wrote: > > yes - but anyway in your example you need "key range quey" and that > requires OOP, right? > > On Tue, Mar 27, 2012 at 5:13 PM, Guy Incognito <dnd1...@gmail.com> wrote: > >> multiget does not require OPP. >> >> On 27/03/2012 09:51, Maciej Miklas wrote: >> >> multiget would require Order Preserving Partitioner, and this can lead to >> unbalanced ring and hot spots. >> >> Maybe you can use secondary index on "itemtype" - is must have small >> cardinality: >> http://pkghosh.wordpress.com/2011/03/02/cassandra-secondary-index-patterns/ >> >> >> >> On Tue, Mar 27, 2012 at 10:10 AM, Guy Incognito <dnd1...@gmail.com>wrote: >> >>> without the ability to do disjoint column slices, i would probably use 5 >>> different rows. >>> >>> userId:itemType -> activityId >>> >>> then it's a multiget slice of 10 items from each of your 5 rows. >>> >>> >>> On 26/03/2012 22:16, Ertio Lew wrote: >>> >>>> I need to store activities by each user, on 5 items types. I always >>>> want to read last 10 activities on each item type, by a user (ie, total >>>> activities to read at a time =50). >>>> >>>> I am wanting to store these activities in a single row for each user so >>>> that they can be retrieved in single row query, since I want to read all >>>> the last 10 activities on each item.. I am thinking of creating composite >>>> names appending "itemtype" : "activityId"(activityId is just timestamp >>>> value) but then, I don't see about how to read the last 10 activities from >>>> all itemtypes. >>>> >>>> Any ideas about schema to do this better way ? >>>> >>> >>> >> >> > >
