Schema questions for data structures with recently-modified access patterns

[Robert Wille]

Data structures that have a recently-modified access pattern seem to be a poor 
fit for Cassandra. I’m wondering if any of you smart guys can provide 
suggestions.

For the sake of discussion, lets assume I have the following tables:

CREATE TABLE document (
        docId UUID,
        doc TEXT,
        last_modified TIMEUUID,
        PRIMARY KEY ((docid))
)

CREATE TABLE doc_by_last_modified (
        date TEXT,
        last_modified TIMEUUID,
        docId UUID,
        PRIMARY KEY ((date), last_modified)
)

When I update a document, I retrieve its last_modified time, delete the current 
record from doc_by_last_modified, and add a new one. Unfortunately, if you’d 
like each document to appear at most once in the doc_by_last_modified table, 
then this doesn’t work so well.

Documents can get into the doc_by_last_modified table multiple times if there 
is concurrent access, or if there is a consistency issue.

Any thoughts out there on how to efficiently provide recently-modified access 
to a table? This problem exists for many types of data structures, not just 
recently-modified. Any ordered data structure that can be dynamically reordered 
suffers from the same problems. As I’ve been doing schema design, this pattern 
keeps recurring. A nice way to address this problem has lots of applications.

Thanks in advance for your thoughts

Robert