> > > 1. Is it possible to "tune" the page size or is it hard-coded internally ? >
If a page size is set for the request at the driver level, that page size will be used internally. Otherwise, it defaults to something reasonable (probably ~5k rows). > 2. Is read-repair performed on EACH page or is it done on the whole > requested rows once they are fetched ? > It's performed on each page as it's read. Do note that read repair doesn't happen for multi-partition range reads, regardless of paging or aggregation. > > Question 2. is relevant in some particular scenarios when the user is > using CL QUORUM (or more) and some replicas are out-of-sync. Even in the > case of aggregation over a single partition, if this partition is wide and > spans many fetch pages, the time the coordinator performs all the > read-repair and reconcile over QUORUM replicas, the query may timeout very > quickly. > Yes, that's possible. Timeouts for these queries should be adjusted accordingly. It's worth noting that the read_request_timeout_in_ms setting applies per-page, so coordinator-level timeouts shouldn't be severely affected by this. -- Tyler Hobbs DataStax <http://datastax.com/>
