There is a memtable per CF, regardless of how many keyspaces you have. I'd pay more attention to the delete/compaction side of things if you are going to be doing that many deletions.
Also, your mail client's formatting is broken. b On Thu, Jul 8, 2010 at 8:45 AM, Dwight Smith <dwight.sm...@alcatel-lucent.com> wrote: > Hi > > > > I am new to Cassandra and am preparing a data model for use in a production > environment, and need to decide if using multiple keyspaces has any > benefit. > > > > There are basically two types of data; the first, large numbers ( ~1750K) > of entries which are written, very few reads, and then removed after several > seconds to several days. The keys are MD5 generated from the content being > written. The second type, ~ 60K, entries written, accessed with > get_range_slices, then based on the time indicated in the content, perform > an action, then delete the specific entry from Cassandra. There are three > columns for the second type, time to action Key ( MD5 of action information > ) – column TimeToScheduleAction, action key to time – column > ScheduledActionToTime, and finally action key to action information - > ActionToScheduledAction. > > > > Currently these are members of two separate keyspaces. Separate keyspaces > were chosen since the data volume was significantly different, and as I > understand, the memtables are dependent upon the data volume, if KeysCached > is not zero. Separate keyspaces would speed up the memtable access for > both. In addition, it seems the compaction would benefit. > > > > Comments please > > > > Thanks much > > > > Dwight > > > > > > CONFIDENTIALITY NOTICE: This e-mail and any files attached may contain > confidential and proprietary information of Alcatel-Lucent and/or its > affiliated entities. Access by the intended recipient only is authorized. > Any liability arising from any party acting, or refraining from acting, on > any information contained in this e-mail is hereby excluded. If you are not > the intended recipient, please notify the sender immediately, destroy the > original transmission and its attachments and do not disclose the contents > to any other person, use it for any purpose, or store or copy the > information in any medium. Copyright in this e-mail and any attachments > belongs to Alcatel-Lucent and/or its affiliated entities.
