secondary indexes in Cassandra under RandomPartitioner

Question

I am researching the possibility of using secondary index feature in Cassandra using Aquiles. I know for the primary index (key), a I must be using OrderPreservingPartitioner in order to query. At first, I thought that with secondary indexes, there is no such limitation, but I noticed that start key is part of GetIndexedSlicesCommand. Does that imply that under RandomPartitioner, this command is unusable?

Answer 1

You don't need OrderPreservingPartitioner to query by row key, it's only needed if you want to get a meaningful range of rows by their key, like 'all rows with a key between 5 and 9'. (Note that can and should almost always use RandomPartitioner instead.)

The start key for get_indexed_slices behaves the same way that it does for get_range_slices. That is, it's not very meaningful for examining a range of rows between two keys when using RandomPartitioner, but it is useful for paging through a lot of rows. There's even a FAQ entry on the topic. Basically, if you're going to get a ton of results from a call to get_indexed_slices, you don't want to fetch them all at once, you want to get a chunk (of 10, 100, or 1000, depending on size) at a time, and then set the start_key to the last key you saw in the previous chunk to get the next chunk.