Hello, Yes this is quite annoying. How did you implement that "external lock"? I also thought of doing an external service that would be dedicated to that. Cassandra client apps would send create instruction to that service, that would receive them and do the creates 1 by 1, and the client app would wait the response from it before starting to insert.
Best, Sébastien. Le mar. 1 juin 2021 à 05:21, Max C. <mc_cassand...@core43.com> a écrit : > In our case we have a shared dev cluster with (for example) a key space > for each developer, a key space for each CI runner, etc. As part of > initializing our test suite we setup the schema to match the code that is > about to be tested. This can mean multiple CI runners each adding/dropping > tables at the same time but for different key spaces. > > Our experience is even though the schema changes do not conflict, we still > run into schema mismatch problems. Our solution to this was to have a > lock (external to Cassandra) that ensures only a single schema change > operation is being issued at a time. > > People assume schema changes in Cassandra work the same way as MySQL or > multiple users editing files on disk — i.e. as long as you’re not editing > the same file (or same MySQL table), then there’s no problem. *This is > NOT the case.* Cassandra schema changes are more like “git push”ing a > commit to the same branch — i.e. at most one change can be outstanding at a > time (across all tables, all key spaces)…otherwise you will run into > trouble. > > Hope that helps. Best of luck. > > - Max > > Hello, >> >> I have a more general question about that, I cannot find clear answer. >> >> In my use case I have many tables (around 10k new tables created per >> months) and they are created from many clients and only dynamically, with >> several clients creating same tables simulteanously. >> >> What is the recommended way of creating tables dynamically? If I am doing >> "if not exists" queries + wait for schema aggreement before and after each >> create statement, will it work correctly for Cassandra? >> >> Sébastien. >> > >
