alter composite primary key in cassandra CQL 3.0
There is no way to change a primary key, as it defines how your data is physically stored. You can create a new table with the new primary key, copy data from the old one, and then drop the old table.
cql3
Cassandra: Generate a unique ID?
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 use the CQL now() method or insert your own, the java … Read more
Results pagination in Cassandra (CQL)
You don’t need to use tokens, if you are using Cassandra 2.0+. Cassandra 2.0 has auto paging. Instead of using token function to create paging, it is now a built-in feature. Now developers can iterate over the entire result set, without having to care that it’s size is larger than the memory. As the client … Read more
Difference between UPDATE and INSERT in Cassandra?
There is a subtle difference. Inserted records via INSERT remain if you set all non-key fields to null. Records inserted via UPDATE go away if you set all non-key fields to null. Try this: CREATE TABLE T ( pk int, f1 int, PRIMARY KEY (pk) ); INSERT INTO T (pk, f1) VALUES (1, 1); UPDATE … Read more
How to auto generate uuid in cassandra CQL 3 command line
As of Cassandra 2.0.7 you can just use uuid(), which generates a random type 4 UUID: INSERT INTO users(uid, name) VALUES(uuid(), ‘my name’);
How do secondary indexes work in Cassandra?
select * from update_audit where scopeid=35 and formid=78005 and record_link_id=9897; How the above query will work internally in cassandra? Essentially, all data for partition scopeid=35 and formid=78005 will be returned, and then filtered by the record_link_id index. It will look for the record_link_id entry for 9897, and attempt to match-up entries that match the rows … Read more
Cassandra UUID vs TimeUUID benefits and disadvantages
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 … Read more