incubator-cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Aditya Narayan <>
Subject Seeking advice on Schema and Caching
Date Tue, 15 Nov 2011 14:50:25 GMT

I need to add 'search users' functionality to my application. (The trigger
for fetching searched items(like google instant search) is made when 3
letters have been typed in).

For this, I make a CF with String type keys. Each such key is made of first
3 letters of a user's name.

Thus all names starting with 'Mar-' are stored in single row (with
The column names are framed as remaining letters of the names. Thus, a name
'Marcos' will be stored within rowkey "Mar" & col name "cos". The id will
be stored as column value. Since there could be many users with same name.
Thus I would have multple userIds(of users named "Marcos") to be stored
inside columnname "cos" under key "Mar". Thus,

1. Supercolumn seems to be a better fit for my use case(so that ids of
users with same name may fit as sub-columns inside a super-column) but
since supercolumns are not encouraged thus I want to use an alternative
schema for this usecase if possible. Could you suggest some ideas on this ?

2. Another thing, I would like to row cache this CF so that when the user
types in the next character & the query is made consequently, then this row
be retrieved from the cache without touching DB. It is expected while
searching for a single username, the query(as a part of making
instantaneous suggestions) will be made at least 2-3 times. One may also
suggest to fetch all the columns starting with queried string to be
retrieved & then filter out at application level but what about just
fecthing the exact no of columns(ids/names of users) I need to show to the
user. Thus instead of keeping all the hundreds of cols in the application
layer what about keeping it within the DB cache.!?
The space alloted for the cache will be very small so that row remains in
cache for a very short time(enough to serve only for the time duration
while user is making a single search!?) ?

View raw message