Jackie-Jiang commented on pull request #5672: URL: https://github.com/apache/incubator-pinot/pull/5672#issuecomment-658316154
> > > Does the `LIMIT 0` query response just contains the projected columns or all columns from schema? If so, do we even need one segment there? We can simply refer to the schema for columns and data types? > > > > > > @mayankshriv `LIMIT 0` query might contain columns and transform functions. So we still need to keep one segment to construct the TransformOperator in order to get all column types. No actual data fetch is required for that single segment. > > @Jackie-Jiang Since we don't enforce schema to be same across segments, wouldn't it be better to have a Schema based operator (perhaps fall back to segment if schema not registered)? @mayankshriv Ideally `LIMIT 0` query should be able to be solved on broker side (where the Schema based operator should be added), but that is out of the scope of this PR. Once we enforce schema, we can add that to avoid the routing overhead. ---------------------------------------------------------------- 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: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@pinot.apache.org For additional commands, e-mail: commits-h...@pinot.apache.org
