Currently, there are several implementations of Catalog that need to use LockManager in their code: HadoopCatalog, GlueCatalog. For GlueCatalog, because I do not use it a lot, I do not do any evaluation of it. For HadoopCatalog, it works fine without LockManager and guarantees atomicity of commits. The reason LockManager is currently in the code is simply because it was added by the previous author. We can remove HadoopCatalog's use of LockManager if needed.
At 2024-07-13 04:52:34, "Amogh Jahagirdar" <2am...@gmail.com> wrote: I have pretty similar concerns as Ryan. I don't think we should be adding any new locking implementations to the project since at the moment the only catalog which requires it for atomic operations is HadoopCatalog (and it doesn't even completely address all the cases). Every locking implementation that gets added to the project pulls in more dependencies and is another dimension of complexity. There were previous discussions in community syncs to deprecate the HadoopCatalog, but if there's a strong desire for retaining it in the project, then a separate module is another approach to isolate that complexity. Thanks, Amogh Jahagirdar On Fri, Jul 12, 2024 at 12:08 PM Ryan Blue <b...@databricks.com.invalid> wrote: I think one of the main questions is whether we want to support locking strategies moving forward. These were needed in early catalogs that didn't have support for atomic operations (HadoopCatalog and GlueCatalog). Now, Glue supports atomic commits and we have been discouraging the use of HadoopCatalog, which is a purely filesystem-based implementation for a long time. One thing to consider is that external locking does solve a few of the challenges of the filesystem-based approach, but doesn't help with many of the shortcomings of the HadoopCatalog, like being able to atomically delete or rename a table. (Operations that are very commonly used in data engineering!) Maybe we should consider moving Hadoop* classes into a separate iceberg-hadoop module, along with the LockManager to make it work somewhat better. Personally, I'd prefer deprecating HadoopCatalog and HadoopTableOperations because of their serious limitations. But moving these into a separate module seems like a good compromise. That would also avoid needing to add dependencies to core, like Redis for lock implementations. Ryan On Thu, Jul 11, 2024 at 10:42 PM lisoda <lis...@yeah.net> wrote: Currently, the only lockManager implementation in iceberg-core is InMemoryLockManager. This PR extends two LockManager implementations, one based on the Redis, and another based on the Rest-API. In general, most users use redisLockManager is sufficient to cope with most of the scenarios, for redis can not meet the user's requirements, we can let the user to provide a RestApi service to achieve this function. I believe that, for a long time, these two lock-manager's will satisfy most of the customer's needs. If someone could review this PR, that would be great. PR: https://github.com/apache/iceberg/pull/10688 SLACK: https://apache-iceberg.slack.com/archives/C03LG1D563F/p1720761992982729 -- Ryan Blue Databricks
