Re: Released an ACID-compliant transaction library on top of Cassandra

hich was followed up by > > > https://www.researchgate.net/profile/Akon_Dey/publication/282156834_Scalable_Distributed_Transactions_across_Heterogeneous_Stores/links/56058b9608ae5e8e3f32b98d.pdf > > > > > > On Tue, Oct 16, 2018 at 1:02 PM Jonathan Ellis wrote: > > &g

Re: Released an ACID-compliant transaction library on top of Cassandra

Hi, Yes this does sound great. Does this rely on Cassandra's internal SERIAL consistency and CAS functionality or is that implemented at a higher level? Regards, Ariel On Tue, Oct 16, 2018, at 12:31 PM, Jeff Jirsa wrote: > This is great! > > -- > Jeff Jirsa > > > > On Oct 16, 2018, at 5:47

Re: bigger data density with Cassandra 4.0?

Hi, It depends on compaction strategy to an extent. Leveled compaction is partitioning sstables on token range so there is a wider variety of scenarios where it works. I haven't done the napkin math at 10 terabytes to figure what % of sstables will be leveled to the point they work with 256 vnodes

Re: How to Parse raw CQL text?

Hi, I took a similar approach and it worked fine. I was able to build a tool that parsed production query logs. I used a helper method that would just grab a private field out of an object by name using reflection. Ariel On Sun, Feb 25, 2018, at 11:58 PM, Jonathan Haddad wrote: > I had to do some

Re: False positive increasing

Jeff is probably correct. I skimmed over the fact that it's just increasing by one every few minutes so I went on about a different scenario. On Mon, Jul 3, 2017, at 01:46 PM, Jeff Jirsa wrote: > > > On 2017-07-03 06:55 (-0700), Jean Carlo > wrote: > > Hello > > > > Lately I am observing that

Re: False positive increasing

Hi, The number of false positives may be increasing because more filters are being consulted on each query. The number of filters consulted on each query is a function of number of sstables consulted. You may be seeing an increase in number of tables consulted if compaction is falling behind. I'm

Re: How does cassandra achieve Linearizability?

NDRA-6246[1] says? > > Thanks, > kant > > On Thu, Feb 16, 2017 at 2:12 PM, Ariel Weisberg > wrote: >> __ >> Hi, >> >> That would work and would help a lot with the dueling proposer issue. >> >> A lot of the leader election stuff is

Re: How does cassandra achieve Linearizability?

l fail the CAS. This is something where a distinguished coordinator could help by failing the rest of the contending requests more inexpensively than it currently does. Ariel On Thu, Feb 16, 2017, at 04:55 PM, Edward Capriolo wrote: > > > On Thu, Feb 16, 2017 at 4:33 PM, Ariel We

Re: How does cassandra achieve Linearizability?

r C* philosophically. Ariel On Thu, Feb 16, 2017, at 04:20 PM, Kant Kodali wrote: > @Ariel Weisberg EPaxos looks very interesting as it looks like it > doesn't need any designated leader for C* but I am assuming the paxos > that is implemented today for LWT's requires Leader electio

Re: How does cassandra achieve Linearizability?

Hi, Cassandra's implementation of Paxos doesn't implement many optimizations that would drastically improve throughput and latency. You need consensus, but it doesn't have to be exorbitantly expensive and fall over under any kind of contention. For instance you could implement EPaxos https://i

Re: Why does `now()` produce different times within the same query?

Hi, The function is defined here[1]. I hope my email client isn't butchering the code. public static final Function *nowFct *= new NativeScalarFunction("now", TimeUUIDType.*instance*) { public ByteBuffer execute(ProtocolVersion protocolVersion, List parameters) { return

Re: JVM safepoints, mmap, and slow disks

ise stuff for this has holes I can't recall right now. Ariel On Mon, Oct 10, 2016, at 02:19 PM, Josh Snyder wrote: > On Sat, Oct 8, 2016 at 9:02 PM, Ariel Weisberg > wrote: > ... > > > You could use this to minimize the cost. > > http://stackoverflow.com/questions/362

Re: JVM safepoints, mmap, and slow disks

t; I do suspect that you’ll see up to about 5-10% sys call overhead if >> you hit pread. >> >> > On Oct 8, 2016, at 11:02 PM, Ariel Weisberg >> > wrote: >> > >> > Hi, >> > >> > This is starting to get into dev lis

Re: JVM safepoints, mmap, and slow disks

hat page (memory) cache can exist if >>>> there is no swap file. >>>> Where are those page written/read? >>>> >>>> >>>> Best regards, Vladimir Yudovin, >>>> *Winguzone[https://winguzone.com/?from=list] - Hosted Cloud Cassandra

Re: JVM safepoints, mmap, and slow disks

gt; Best regards, Vladimir Yudovin, > *Winguzone[1] - Hosted Cloud Cassandra on Azure and SoftLayer. Launch > your cluster in minutes. * > > > On Sat, 08 Oct 2016 13:40:19 -0400 *Ariel Weisberg > * wrote >> Hi, >> >> Page cache is in use even if you di

Re: JVM safepoints, mmap, and slow disks

Hi, Page cache is in use even if you disable swap. Swap is anonymous memory, and whatever else the Linux kernel supports paging out. Page cache is data pending flush to disk and data cached from disk. Given how bad the GC pauses are in C* I think it's not the high pole in the tent. Until key thin

Re: Guidelines for configuring Thresholds for Cassandra metrics

Hi, Apologies for a dev related hijack. We can continue the dev related discussion in JIRA or the dev list. Seeing this discussion makes me think that Benedict and Ryan you will both have opinions about https://issues.apache.org/jira/browse/CASSANDRA-12372 (remove memtable_cleanup_threshold, not

Re: I am a Datastax certified Cassandra architect now :)

Hi, Congratulations! I hope the certification brings good things for you. Regards, Ariel On Sun, Nov 22, 2015, at 01:00 PM, Prem Yadav wrote: > Just letting the community know that I just passed the Cassandra > architect certification with flying colors :). Have to say I learnt a > lot from thi

Re: A new Java Zero Day exploit is affecting Java 1.8.0.45

Hi, Sounds like this isn’t an issue with the runtime. It’s another plugin/webstart/whatever desktop issue that doesn’t effect servers. I Googled but didn’t find a precise description of what the issue is. Regards, Ariel > On Jul 14, 2015, at 3:31 PM, Marcos Ortiz wrote: > > Regards to all Cas

Re: Best partition type for Cassandra with JBOD

Hi, Recommending nobarrier (mount option barrier=0) when you don't know if a non-volatile cache in play is probably not the way to go. A non-volatile cache will typically ignore write barriers if a given block device is configured to cache writes anyways. I am also skeptical you will see a bo

Re: DSE Hadoop support for provisioning hardware

ch other, but > the data in each is seamlessly replicated so that both are always up to > date, without you having to write ETL code. > > Does that answer your question? > > -Jeremiah > > > On Mar 11, 2014, at 10:27 AM, Ariel Weisberg wrote: > > > Hi, > > &g

DSE Hadoop support for provisioning hardware

Hi, I am doing a presentation at Big Data Boston about how people are bridging the gap between OLTP and ingest side databases and their analytic storage and queries. One class of systems I am talking about are things like HBase and DSE that let you run map reduce against your OLTP dataset. I reme

Re: Guaranteeing globally unique TimeUUID's in a high throughput distributed system

Hi, This has been solved a couple of times, and always pretty much the same way. Encode the id of the worker generating the id into the timestamp, and as you mentioned, maintain a counter for each millisecond. [1]https://github.com/twitter/snowflake [2]https://github.com/VoltDB/voltdb/blob/m