If you don't have any intent on running across multiple nodes, Cassandra is probably the wrong DB for you.
Postgres will give you a better feature set for a single node. On Fri, Aug 30, 2019 at 5:23 AM Pankaj Gajjar <pankaj.gaj...@contentserv.com> wrote: > Understand it well, how about Cassandra running on single node, we don’t > have cluster setup (3 nodes+ i.e). > > Does MVs perform well on single node machine ? > > Note: I know about HA, so lets keep it side for now and it's only possible > when we have cluster setup. > > On 29/08/19, 06:21, "Dor Laor" <d...@scylladb.com> wrote: > > On Wed, Aug 28, 2019 at 5:43 PM Jon Haddad <j...@jonhaddad.com> wrote: > > > > Arguably, the other alternative to server-side denormalization is > to do > > the denormalization client-side which comes with the same axes of > costs and > > complexity, just with more of each. > > > > That's not completely true. You can write to any number of tables > without > > doing a read, and the cost of reading data off disk is significantly > > greater than an insert alone. You can crush a cluster with a write > heavy > > workload and MVs that would otherwise be completely fine to do all > writes. > > > > The other issue with MVs is that you still need to understand > fundamentals > > of data modeling, that don't magically solve the problem of enormous > > partitions. One of the reasons I've had to un-MV a lot of clusters > is > > because people have put an MV on a table with a low-cardinality > field and > > found themselves with a 10GB partition nightmare, so they need to go > back > > and remodel the view as something more complex anyways. In this > case, the > > MV was extremely high cost since now they've not only pushed out a > poor > > implementation to begin with but now have the cost of a migration as > well > > as a rewrite. > > > > +1 > > Moreover, the hard part is that an update for the base table means that > the original data needs to be read and the database (or the poor > developer > who implements the denormalized model) needs to delete the data in the > view > and then to write the new ones. All need to be of course resilient to > all > types of > errors and failures. Had it been simple, there was no need for a > database > MV.. > > > > > > > > > > On Wed, Aug 28, 2019 at 9:58 AM Joshua McKenzie < > jmcken...@apache.org> > > wrote: > > > > > > > > > > so we need to start migration from MVs to manual query base > table ? > > > > > > Arguably, the other alternative to server-side denormalization is > to do > > > the denormalization client-side which comes with the same axes of > costs > > and > > > complexity, just with more of each. > > > > > > Jeff's spot on when he discusses the risk appetite vs. mitigation > aspect > > of > > > it. There's a reason banks do end-of-day close-out validation > analysis > > and > > > have redundant systems for things like this. > > > > > > On Wed, Aug 28, 2019 at 11:49 AM Jon Haddad <j...@jonhaddad.com> > wrote: > > > > > > > I've helped a lot of teams (a dozen to two dozen maybe) migrate > away > > from > > > > MVs due to inconsistencies, issues with streaming (have you > added or > > > > removed nodes yet?), and massive performance issues to the point > of > > > cluster > > > > failure under (what I consider) trivial load. I haven't gone > too deep > > > into > > > > analyzing their issues, folks are usually fine with "move off > them", vs > > > > having me do a ton of analysis. > > > > > > > > tlp-stress has a materialized view workload built in, and you > can add > > > > arbitrary CQL via the --cql flag to add a MV to any existing > workload > > > such > > > > as KeyValue or BasicTimeSeries. > > > > > > > > On Wed, Aug 28, 2019 at 8:11 AM Jeff Jirsa <jji...@gmail.com> > wrote: > > > > > > > > > There have been people who have had operational issues related > to MVs > > > > (many > > > > > of them around running repair), but the biggest concern is > > correctness. > > > > > > > > > > It probably ultimately depends on what type of database you're > > running. > > > > If > > > > > you're running some sort of IOT / analytics workload and you > just > > want > > > > > another way to SELECT the data, but you won't notice one of a > billion > > > > > records going missing, using MVs may be fine. If you're a > bank, and > > one > > > > of > > > > > a billion records going missing means you lose someone's bank > > account, > > > I > > > > > would avoid using MVs. > > > > > > > > > > It's all just risk management. > > > > > > > > > > On Wed, Aug 28, 2019 at 7:18 AM Pankaj Gajjar < > > > > > pankaj.gaj...@contentserv.com> > > > > > wrote: > > > > > > > > > > > Hi Michael, > > > > > > > > > > > > Thanks for putting very clever information " Users of MVs > *must* > > > > > determine > > > > > > for themselves, through > > > > > > thorough testing and understanding, if they wish to use > them." > > > And > > > > > > this concluded that if there is any issue occur in future > then only > > > > > > solution is to rebuild the MVs since Cassandra does not able > to > > make > > > > > > consistent synch well. > > > > > > > > > > > > Also, we practically using the 10+ MVs and as of now, we > have not > > > faced > > > > > > any issue, so my question to all community member, does > anyone face > > > any > > > > > > critical issues ? so we need to start migration from MVs to > manual > > > > query > > > > > > base table ? > > > > > > > > > > > > Also, I can understand now, it's experimental and not ready > for > > > > > > production, so if possible, please ignore it only right ? > > > > > > > > > > > > Thanks > > > > > > Pankaj > > > > > > > > > > > > On 27/08/19, 19:03, "Michael Shuler" <mshu...@pbandjelly.org > on > > > > behalf > > > > > > of mich...@pbandjelly.org> wrote: > > > > > > > > > > > > It appears that you found the first message of the > chain. I > > > suggest > > > > > > reading the linked JIRA and the complete dev@ thread > that > > > arrived > > > > at > > > > > > this conclusion; there are loads of well formed opinions > and > > > > > > information. Users of MVs *must* determine for > themselves, > > > through > > > > > > thorough testing and understanding, if they wish to use > them. > > > > > > > > > > > > Linkage: > > > > > > https://issues.apache.org/jira/browse/CASSANDRA-13959 > > > > > > (sub-linkage..) > > > > > > https://issues.apache.org/jira/browse/CASSANDRA-13595 > > > > > > https://issues.apache.org/jira/browse/CASSANDRA-13911 > > > > > > https://issues.apache.org/jira/browse/CASSANDRA-13880 > > > > > > https://issues.apache.org/jira/browse/CASSANDRA-12872 > > > > > > https://issues.apache.org/jira/browse/CASSANDRA-13747 > > > > > > > > > > > > Very much worth reading the complete thread: > > > > > > part1: > > > > > > > > > > > > > > > > > > > > > > > > > > > https://lists.apache.org/thread.html/d81a61da48e1b872d7599df4edfa8e244d34cbd591a18539f724796f@ > > > > > > <dev.cassandra.apache.org> > > > > > > part2: > > > > > > > > > > > > > > > > > > > > > > > > > > > https://lists.apache.org/thread.html/19b7fcfd3b47f1526d6e993b3bb97f6c43e5ce204bc976ec0701cdd3@ > > > > > > <dev.cassandra.apache.org> > > > > > > > > > > > > Quick JQL for open tickets with "mv": > > > > > > > > > > > > > > > > > > > > > > > > > > > https://issues.apache.org/jira/issues/?jql=project%20%3D%20CASSANDRA%20AND%20text%20~%20mv%20AND%20status%20!%3D%20Resolved > > > > > > > > > > > > -- > > > > > > Michael > > > > > > > > > > > > On 8/27/19 5:01 AM, pankaj gajjar wrote: > > > > > > > Hello, > > > > > > > > > > > > > > > > > > > > > > > > > > > > concern about Materialized Views (MVs) in Cassandra. > > > > Unfortunately > > > > > > starting > > > > > > > with version 3.11, MVs are officially considered > experimental > > > and > > > > > > not ready > > > > > > > for production use, as you can read here: > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > http://mail-archives.apache.org/mod_mbox/cassandra-user/201710.mbox/%3cetpan.59f24f38.438f4e99.7...@apple.com%3E > > > > > > > > > > > > > > > > > > > > > > > > > > > > Can you please someone give some productive feedback > on this > > ? > > > it > > > > > > would > > > > > > > help us to further implementation around the MVs in > > Cassandra. > > > > > > > > > > > > > > > > > > > > > > > > > > > > Does anyone facing some critical issue or data lose or > > > > > > synchronization > > > > > > > issue ? > > > > > > > > > > > > > > > > > > > > > > > > > > > > Regards > > > > > > > > > > > > > > Pankaj. > > > > > > > > > > > > > > > > > > > > > > > > --------------------------------------------------------------------- > > > > > > To unsubscribe, e-mail: > dev-unsubscr...@cassandra.apache.org > > > > > > For additional commands, e-mail: > dev-h...@cassandra.apache.org > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
