As you may know, SuperColumn Tables did not work in 3.x the way they worked in 2.x. In order to provide everyone with a reasonable upgrade path, we've been working on CASSANDRA-12373[1], that brings in support for SuperColumn tables as close to 2.x as possible. The patch is planned to land cassandra-3.0 and cassandra-3.11 branches only, since the patch for trunk will require even more work and, since thrift is not supported on trunk/4.0, it makes it much less appealing or even necessary. The idea behind the support for SuperColumns was always only to allow people to smoothly migrate off them in 3.0/3.11 world, not to have them as a primary feature.
SuperColumns are not the only type of Compact Table, there are more. After CASSANDRA-8099[2], Compact Tables are special-cased and have special schema layout with some columns hidden from CQL, that allows them to be used from Thrift. But, except for the fact they’re accessible from Thrift, there are no advantages to use them with the new storage. In order to allow people to “expose” the internal structure of the compact tables to make them fully accessible in CQL, CASSANDRA-10857[3] was created. In the light of the fact that 4.0 will not have reasonable SuperColumn support (due to related complexity and amount of special-cases required to support it in 4.0) and a possibility drop a Compact Storage flag and expose them as “normal" tables, there was an idea of removing the Compact Tables from 4.x altogether. Leaving Compact Storage in 3.x only will make the table metadata a bit lighter and allow us to remove some special cases required for their support. Doing it during the major release, provided with a reasonable upgrade path (same functionality from both Thrift and CQL for all compact tables, including Super Column ones) through 3.x/3.11, sounds like the best option that we have right now. It’d be good if you could voice your support of this idea (or raise possible concerns, if there are any). There will be additional discussion and a proposal on how to allow “online” COMPACT STORAGE flag drop in CASSANDRA-10857 later this (or the following week). Best Regards, Alex [1] https://issues.apache.org/jira/browse/CASSANDRA-12373 <https://issues.apache.org/jira/browse/CASSANDRA-12373> [2] https://issues.apache.org/jira/browse/CASSANDRA-8099 <https://issues.apache.org/jira/browse/CASSANDRA-8099> [3] https://issues.apache.org/jira/browse/CASSANDRA-10857 <https://issues.apache.org/jira/browse/CASSANDRA-10857>
