Change Details

When `allow_overwrite` is False (the default), the Cassandra storage checks if objects exist before inserting them. This is best-effort, (because other workers may write between this check and the actual write anyway), so only meant as a performance optimization. This check is performed with the same consistency level as other queries, ie. `QUORUM` in production. However, since this is already vulnerable to TOCTOU issues, I think we should lower this level to `1`. This lowers the load by sending queries to fewer nodes, and lowers latency of the query itself.

When `allow_overwrite` is False (the default), the Cassandra storage checks if objects exist before inserting them. This is best-effort, (because other workers may write between this check and the actual write anyway), so only meant as a performance optimization. This check is performed with the same consistency level as other queries, ie. `QUORUM` in production. However, since this is already vulnerable to TOCTOU issues, I think we might as well lower this level to `1`. This lowers the load by sending queries to fewer nodes, and lowers latency of the query itself.

When `allow_overwrite` is False (the default), the Cassandra storage checks if objects exist before inserting them. This is best-effort, (because other workers may write between this check and the actual write anyway), so only meant as a performance optimization. This check is performed with the same consistency level as other queries, ie. `QUORUM` in production. However, since this is already vulnerable to TOCTOU issues, I think we shouldmight as well lower this level to `1`. This lowers the load by sending queries to fewer nodes, and lowers latency of the query itself.