How does ScyllaDB/Cassandra handle partial update?

Question

Assuming there is one row which has 10 columns.

If I only update one column, before the merging/compaction, will the database create a new partition with only the updated column (containing the new value) in SSTable or it will create a new partition with all the 10 columns (the new column containing the new value)?

Answer 1

Just the one column will be written, it's a bit different pre/post 3.0 on how its actually stored though. You can use the sstabledump tool to examine whats actually stored to test it if you would like.