in my #2 example: select * from people where company_id='xxx' and gender='male'
I already specify the first part of the primary key(row key) in my where clause, so how does the secondary indexed column gender='male" help determine which row to return? It is more like filtering a list of column from a row(which is exactly I can do that in #1 example). But then if I don't create index first, the cql statement will run into syntax error. On Tue, Jan 28, 2014 at 11:37 AM, Mullen, Robert <robert.mul...@pearson.com>wrote: > I would do #2. Take a look at this blog which talks about secondary > indexes, cardinality, and what it means for cassandra. Secondary indexes > in cassandra are a different beast, so often old rules of thumb about > indexes don't apply. http://www.wentnet.com/blog/?p=77 > > > On Tue, Jan 28, 2014 at 10:41 AM, Edward Capriolo > <edlinuxg...@gmail.com>wrote: > >> Generally indexes on binary fields true/false male/female are not >> terrible effective. >> >> >> On Tue, Jan 28, 2014 at 12:40 PM, Jimmy Lin <y2klyf+w...@gmail.com>wrote: >> >>> I have a simple column family like the following >>> >>> create table people( >>> company_id text, >>> employee_id text, >>> gender text, >>> primary key(company_id, employee_id) >>> ); >>> >>> if I want to find out all the "male" employee given a company id, I can >>> do >>> >>> 1/ >>> select * from people where company_id=xxxx' >>> and loop through the result efficiently to pick the employee who has >>> gender column value equal to "male" >>> >>> 2/ >>> add a seconday index >>> create index gender_index on people(gender) >>> select * from people where company_id='xxx' and gender='male' >>> >>> >>> I though #2 seems more appropriate, but I also thought the secondary >>> index is helping only locating the primary row key, with the select clause >>> in #2, is it more efficient than #1 where application responsible loop >>> through the result and filter the right content? >>> >>> ( >>> It totally make sense if I only need to find out all the male >>> employee(and not within a company) by using >>> select * from people where gender='male" >>> ) >>> >>> thanks >>> >> >> >
