xhochy commented on pull request #7357: URL: https://github.com/apache/arrow/pull/7357#issuecomment-642456798
> * should Jira issues and PR's be 1 tot 1, or can I open multiple PR's referencing the same Jira issue At least one JIRA pr PR, everything should have an issue number. If there isn't a need for more explanation, a title with correct tagging is enough. It would be helpful to have such JIRAs also to coordinate who is working which task. > * 1 commit per PR, or multiple commits per PR if related, but each commit one idea/topic/functionlity? As many commits as it makes sense to review, we will squash on merge. The important detail in the past that was annoying (also can be helpful) is that reviewers will not be notified for changes if you force-push. > I have to dive a bit into how the kernels work, but with the current implementation of ascii_lower and upper I see performance issues (we should be able to write into a pre-allocated buffer, since we know the byte length). I'm happy first getting some basic functionality in, and optimize later, it will surface the issues around the framework a bit more I think. I'm also quite concerned about this performance penalty. But for e.g. `utf8_upper` (let's just call it `upper`), I expect that we cannot pre-allocate and thus these are the things where we could continue to as-is. I'm happy to merge this PR (with a new JIRA id), we should though work on writing into pre-allocated memory before writing more kernels that would greatly benefit from pre-allocation. For optimization in the pre-allocated case, this should be a sufficient baseline. I'm more concerned about performance when we start to implement UTF-8 based functionality as we quickly get to the point where we need to look at multiple bytes at a time but don't know ahead whether it's 1, 2, 3, or 4. There we probably should implement kernels with decent performance and one we have a set of 5-10, we can look on how to improve performance there. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected]
