Yes, it will put the whole row in cache even if you read only a bunch of columns. It means in particular that with row cache, every time you read a row, the full row will be read on a cache miss. Thus it may hurts you read badly in some scenario (typically with big rows) instead of helping them. Enable row cache wisely :)
-- Sylvain On Wed, Apr 14, 2010 at 3:06 AM, Paul Prescod <pres...@gmail.com> wrote: > On Tue, Apr 13, 2010 at 5:26 PM, Rob Coli <rc...@digg.com> wrote: >> On 4/13/10 5:04 PM, Paul Prescod wrote: >>> >>> Am I correct in my understanding that the unit of caching (and >>> fetching from disk?) is a full row? >> >> Cassandra has both a Key and a Row cache. Unfortunately there appears to be >> no current wiki doc describing them. If you are looking into the topic, wiki >> updates are always appreciated. :) > > Yeah, sorry I knew that but I was asking specifically about if there > was any caching within a row that is more granular than the whole row. > It looks to me like it doesn't just cache the columns you asked for, > but all columns in the row. This obviously has some interesting > implications for keys that are large "indexes" in a single row. > > Paul Prescod >
