> i was just wondering if anyone else is experiencing very slow ( ~ 3.5 MB/sec > ) re-fill of the row cache at start up. It was mentioned the other day.
What version are you on ? Do you know how many rows were loaded ? When complete it will log a message with the pattern "completed loading (%d ms; %d keys) row cache for %s.%s" > How is the "saved row cache file" processed? In Version 1.1, after the SSTables have been opened the keys in the saved row cache are read one at a time and the whole row read into memory. This is a single threaded operation. In 1.2 reading the saved cache is still single threaded, but reading the rows goes through the read thread pool so is in parallel. In both cases I do not believe the cache is stored in token (or key) order. > ( Admittedly whatever is going on is still much more preferable to starting > with a cold row cache ) row_cache_keys_to_save in yaml may help you find a happy half way point. Cheers ----------------- Aaron Morton Freelance Cassandra Developer New Zealand @aaronmorton http://www.thelastpickle.com On 20/11/2012, at 3:17 AM, Andras Szerdahelyi <andras.szerdahe...@ignitionone.com> wrote: > Hey list, > > i was just wondering if anyone else is experiencing very slow ( ~ 3.5 MB/sec > ) re-fill of the row cache at start up. We operate with a large row cache ( > 10-15GB currently ) and we already measure startup times in hours :-) > > How is the "saved row cache file" processed? Are the cached row keys simply > iterated over and their respective rows read from SSTables - possibly > creating random reads with small enough sstable files, if the keys were not > stored in a manner optimised for a quick re-fill ? - or is there a smarter > algorithm ( i.e. scan through one sstable at a time, filter rows that should > be in row cache ) at work and this operation is purely disk i/o bound ? > > ( Admittedly whatever is going on is still much more preferable to starting > with a cold row cache ) > > thanks! > Andras > > > > Andras Szerdahelyi > Solutions Architect, IgnitionOne | 1831 Diegem E.Mommaertslaan 20A > M: +32 493 05 50 88 | Skype: sandrew84 > > > <C4798BB9-9092-4145-880B-A72C6B7AF9A4[41].png> > >
