rohangarg commented on PR #13553: URL: https://github.com/apache/druid/pull/13553#issuecomment-1346167353
@paul-rogers @imply-cheddar : This proposes an alternate way to extend the `FROM` grammar in Calcite. The new changes merged recently for extended table functions use a script `edit-parser` to update the parser file and added the new production rules in it. While technically currently that is the only way to extend `FROM` grammar in calcite for now, the script method is a bit difficult to use for the following reasons : 1. Doing more complex operations/edits on the grammar is a bit tricky in the script 2. Getting a whole view of the extended grammar from code is a bit hard since the script generates the new parser dynamically 3. Since the update is dynamic, every update requires a search and replace which makes the update a bit fragile and susceptible to logical problems when the underlying grammar updates An alternative approach tried in this change is to pull the relevant production rules from the calcite grammar and have them as template files which can be edited as per druid's usecases. This provides full control over the pulled production rule, a simple full view of the augmented grammar and also lesser search-replace operations (one in the current case in the pom file). Please let me know your thoughts on it! -- 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. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
