This PR fixes several bugs related to handling of non-full
clustering keys.
One is in trim_clustering_row_ranges_to(), which is broken for non-full keys in reverse
mode. It will trim the range to position_in_partition_view::after_key(full_key) instead of
position_in_partition_view::before_key(key), hence it will include the
key in the resulting range rather than exclude it.
Fixes#12180
after_key() was creating a position which is after all keys prefixed
by a non-full key, rather than a position which is right after that
key.
This will issue will be caught by cql_query_test::test_compact_storage
in debug mode when mutation_partition_v2 merging starts inserting
sentinels at position after_key() on preemption.
It probably already causes problems for such keys as after_key() is used
in various parts in the read path.
Refs #1446Closes#12234
* github.com:scylladb/scylladb:
position_in_partition: Make after_key() work with non-full keys
position_in_partition: Introduce before_key(position_in_partition_view)
db: Fix trim_clustering_row_ranges_to() for non-full keys and reverse order
types: Fix comparison of frozen sets with empty values