Comments inline 2009/8/4 Onur AKTAS <[email protected]>: > > I'm confused about the when to use HBase. (Sure I have read everything and > every link on http://wiki.apache.org/hadoop/Hbase/FAQ) > Its distributed (when used on Hadoop) and provides efficient database for > "VERY LARGE" amounts of datas, thats ok. > > But as I come from RDBMS world, i want to learn what I can do with HBase and > how it can affect the quality of my applications. > > For example, as I also see on "HBase Schema Design Case Studies" referenced > by FAQ, "Case 4: user-friends", there is something like > user: id > info: name > info: sex > info: age > friend: user_id1 > friend: user_id2 > etc..
It's possibly worth pointing out, that a userinfo table will quite likely fit fine inside a relational db like postgres. > > 1- Let me understand the concept, Is there anyway to delete user's id from > all of his/her friends' friend column? There is no foreign key relation then > this is the thing that we must handle programmatically? > That's correct, there is no way to do this automatically, there are no relations in HBase. > 2- Is it also useful when the data is small but the calculations on it is > complex? For example, "calculating the degree of contacts" ? > HBase 0.20 handles small cells fine, eg. I've loaded a 700 million cell table of integers. You can run map reduce jobs over the whole table if you want to do processing. > 3- Some high traffic applications like making Facebook's, twitter's live > status feed with HBase is possible? (Distribution of feeds to friend lists > etc.) > I can't really answer that, as I haven't used it in this way. It has a really good write throughput though. You could optimise for this case. In memory tables etcetera. You'd want to not run any map reduce over it at the same time. > Or > Its main goal is to analyse whole data and calculations for the internal use? > Not for serving them to users in realtime like RDBMS? HBase 0.20 can handle real time now. See http://devblog.streamy.com/2009/07/24/streamy-hadoop-summit-hbase-goes-realtime/ > > Thank you so much. hope that helps. ~Tim
