Hi list, the content of virtual tables is held in memory (and / or is fetched every time upon request). While doing queries against such table for a column outside of primary key, normally, users are required to specify ALLOW FILTERING. This makes total sense for "ordinary tables" for applications to have performant and effective queries but it kinds of loses the applicability for virtual tables when it literally holds just handful of entries in memory and it just does not matter, does it?
What do you think about implicitly allowing filtering for virtual tables so we save ourselves from these pesky errors when we want to query arbitrary column and we need to satisfy CQL spec just to do that? It is not like we would promote bad habits because virtual tables are meant to be queried by operators / administrators only. We can also explicitly document this behavior. Among other options, we may try to implement secondary indices on virtual tables but I am not completely sure this is what we want because its complexity etc. Is it even necessary to put such complex logic in place just to be able to select any column on few entries in memory? I put together a draft here (1). It would be ever possible to implicitly allow filtering on virtual tables only and it would be implementator's responsibility to decide that, per table. For all virtual tables we currently have, I would enable this everywhere. I do not think there is any virtual table where we would not want to enable it or where people HAVE TO specify that. (1) https://github.com/apache/cassandra/pull/2131
