When I say "rows in the slice" I mean "columns in the slice", sorry for the typo.
El jue, 21-10-2010 a las 17:44 +0200, Héctor Izquierdo Seliva escribió: > El jue, 21-10-2010 a las 00:02 -0500, Jonathan Ellis escribió: > > I don't think it's possible. Cassandra's data model means you can't > > know what columns are present in a row, so if you query, say, name and > > birthdate from your users column family and only the name column is in > > the cache for the row you are querying, does that mean that birthdate > > doesn't exist in that row? Or just that it's not cached? You don't > > know, so you'd have to do a full read every time. Similar > > difficulties arise with slices. > > I was thinking in a column cache to be used when you need a slice of a > row, where you'd ask the cache for all the rows in the slice, and then > read from disk whichever rows weren't in cache. If the columns you want > don't exist, you still hit the disk, but you get a nice speedup for > existing columns. > > If you want write-through cache then things complicate a bit, but it > should be doable. > > The question is, would the performance improvement justifies the > increase in complexity? > > > > > > > 2010/10/20 Héctor Izquierdo Seliva <izquie...@strands.com>: > > > Hi. Before wasting time in something that might not be feasible at the > > > moment, I wanted to ask the devs if a column cache would be possible > > > (instead of a whole row cache). This would allow users with fat rows to > > > also use a cache and reduce latency for hot data. > > > > > > If this is possible, i'd appreciate some hints about where to dig. > > > > > > Thanks for your time! > > > > > > > > > > > > > >
