Hi Chris, Thanks for the response!
What kind of challenges did you run into that kept you from using collections? I currently and running 4 physical nodes, same as I was with case 1.1.6. I'm using size tiered compaction. Would changing to level tiered with a large minimum make a big difference, or would it just push the problem off till later? Yeah, I have run into problems dropping schemas before as well. I was careful this time to start with an empty db folder… Glad you were successful in your transition…:) Paul On Jul 24, 2013, at 4:12 AM, "Christopher Wirt" <chris.w...@struq.com> wrote: > Hi Paul, > > Sorry to hear you’re having a low point. > > We ended up not using the collection features of 1.2. > Instead storing a compressed string containing the map and handling client > side. > > We only have fixed schema short rows so no experience with large row > compaction. > > File descriptors have never got that high for us. But, if you only have a > couple physical nodes with loads of data and small ss-tables maybe they could > get that high? > > Only time I’ve had file descriptors get out of hand was then compaction got > slightly confused with a new schema when I dropped and recreated instead of > truncating. https://issues.apache.org/jira/browse/CASSANDRA-4857 restarting > the node fixed the issue. > > > From my limited experience I think Cassandra is a dangerous choice for an > young limited funding/experience start-up expecting to scale fast. We are a > fairly mature start-up with funding. We’ve just spent 3-5 months moving from > Mongo to Cassandra. It’s been expensive and painful getting Cassandra to read > like Mongo, but we’ve made it J > > > > > From: Paul Ingalls [mailto:paulinga...@gmail.com] > Sent: 24 July 2013 06:01 > To: user@cassandra.apache.org > Subject: disappointed > > I want to check in. I'm sad, mad and afraid. I've been trying to get a 1.2 > cluster up and working with my data set for three weeks with no success. > I've been running a 1.1 cluster for 8 months now with no hiccups, but for me > at least 1.2 has been a disaster. I had high hopes for leveraging the new > features of 1.2, specifically vnodes and collections. But at this point I > can't release my system into production, and will probably need to find a new > back end. As a small startup, this could be catastrophic. I'm mostly mad at > myself. I took a risk moving to the new tech. I forgot sometimes when you > gamble, you lose. > > First, the performance of 1.2.6 was horrible when using collections. I > wasn't able to push through 500k rows before the cluster became unusable. > With a lot of digging, and way too much time, I discovered I was hitting a > bug that had just been fixed, but was unreleased. This scared me, because > the release was already at 1.2.6 and I would have expected something as > https://issues.apache.org/jira/browse/CASSANDRA-5677 would have been > addressed long before. But gamely I grabbed the latest code from the 1.2 > branch, built it and I was finally able to get past half a million rows. > > But, then I hit ~4 million rows, and a multitude of problems. Even with the > fix above, I was still seeing a ton of compactions failing, specifically the > ones for large rows. Not a single large row will compact, they all assert > with the wrong size. Worse, and this is what kills the whole thing, I keep > hitting a wall with open files, even after dumping the whole DB, dropping > vnodes and trying again. Seriously, 650k open file descriptors? When it > hits this limit, the whole DB craps out and is basically unusable. This > isn't that many rows. I have close to a half a billion in 1.1… > > I'm now at a standstill. I figure I have two options unless someone here can > help me. Neither of them involve 1.2. I can either go back to 1.1 and > remove the features that collections added to my service, or I find another > data backend that has similar performance characteristics to cassandra but > allows collections type behavior in a scalable manner. Cause as far as I can > tell, 1.2 doesn't scale. Which makes me sad, I was proud of what I > accomplished with 1.1…. > > Does anyone know why there are so many open file descriptors? Any ideas on > why a large row won't compact? > > Paul
