cql3

As there are two ways to support wide rows in CQL3..One is to use composite keys and another is to use collections like Map, List and Set. The composite keys method can have millions of columns (transposed to rows).. This is solving some of our use cases. However, if we use collections, I want to know if there is a limit that the collections can store a certain number/amount of data (Like earlier with Thrift C* supports up-to 2 billion columns in a row) Apart from the performance issue, there is a protocol issue which limits the number of items you can access to 65536. http://mail-archives

I am trying to run the following query SELECT edge_id, b_id FROM booking_by_edge WHERE edge_id IN ? I bind Java list of Long's as a parameter and I get an exception SyntaxError: line 0:-1 mismatched input '<EOF>' expecting ')' (ResultSetFuture.java:242) If I try to use (?) it expects single Long item to be bound, but I need a collection Is there an error in my syntax? Tested in Cassandra 2.1.3, the following code snippet works: PreparedStatement prepared = session.prepare("SELECT edge_id, b_id FROM booking_by_edge WHERE edge_id IN ?;"); List<Long> edgeIds = Arrays.asList(1L, 2L, 3L); session

At the Cassandra Summit, it was mentioned that Thrift and CQL 3 have subtle differences in their definitions of columns and rows. The Google hasn't helped me understand this difference. The only information I can find is that the metadata is different, and as such, I shouldn't mix thrift and CQL. What is the subtle difference (I've read a bit about metadata representations...)? in what way does it break the compatibility? Why is the change better? I'm happy to read any docs that will help me, I've just been unable to find anything specifically related to this topic. Here's the reading path I

I am evaluating cassandra. I am using the datastax driver and CQL. I would like to store some data with the following internal structure, where the names are different for each update. +-------+-------+-------+-------+-------+-------+ | | name1 | name2 | name3 | ... | nameN | | time +-------+-------+-------+-------+-------+ | | val1 | val2 | val3 | ... | valN | +-------+-------+-------+-------|-------+-------+ So time should be the column key, and name should be the row key. The CQL statement I use to create this table is: CREATE TABLE IF NOT EXISTS test.wide ( time varchar, name varchar,

I'm working on a distributed data base. I'm trying to generate a unique ID that will serve as a column family primary key in cassandra . I read some articles about doing this with Java using UUID but it seems like there is a probability for collision (even if it's very low). I wonder if there is a way to generate a unique ID based on time maybe? Richard You can use the TimeUUID type in Cassandra, which backs a Type 1 UUID . This uses the current time and the creator's MAC address and a sequence number. If the TimeUUID number is generated correctly this can be done with zero collisions (you can

In several places it's advised to design our Cassandra tables according to the queries we are going to perform on them. In this article by DataScale they state this: The truth is that having many similar tables with similar data is a good thing in Cassandra. Limit the primary key to exactly what you’ll be searching with. If you plan on searching the data with a similar, but different criteria, then make it a separate table. There is no drawback for having the same data stored differently. Duplication of data is your friend in Cassandra. [...] If you need to store the same piece of data in 14

I am wondering how can I achieve pagination using Cassandra. Let us say that I have a blog. The blog lists max 10 posts per page. To access next posts a user must click on pagination menu to access page 2 (posts 11-20), page 3 (posts 21-30), etc. Using SQL under MySQL, I could do the following: SELECT * FROM posts LIMIT 20,10; The first parameter of LIMIT is offset from the beginning of result set and second argument is amount of rows to fetch. The example above returns 10 rows starting from row 20. How can I achieve the same effect in CQL? I have found some solutions on Google, but all of

Given that TimeUUID handily allows you to use now() in CQL, are there any reasons you wouldn't just go ahead and always use TimeUUID instead of plain old UUID? UUID and TIMEUUID are stored the same way in Cassandra, and they only really represent two different sorting implementations. TIMEUUID columns are sorted by their time components first, and then by their raw bytes, whereas UUID columns are sorted by their version first, then if both are version 1 by their time component, and finally by their raw bytes. Curiosly the time component sorting implementations are duplicated between UUIDType