We never read from backups on partitioned cache, but for replicated we do that to be able to execute the whole query on single node locally.
Sergi 2017-04-18 12:07 GMT+03:00 Dmitriy Setrakyan <dsetrak...@apache.org>: > Sergi, I am confused. If we don't read from backups, then why do we care > about sync or async backup updates? > > On Tue, Apr 18, 2017 at 1:11 AM, Sergi Vladykin <sergi.vlady...@gmail.com> > wrote: > > > Val, > > > > There we were not able to run queries against partitioned tables using > > replicated cache API (I already fixed that in master). > > > > Here we are talking about query result inconsistency in case of > > PRIMARY_SYNC > > because of async backup update. > > > > Sergi > > > > 2017-04-18 11:04 GMT+03:00 Valentin Kulichenko < > > valentin.kuliche...@gmail.com>: > > > > > Can you please elaborate then? What is the logic there? > > > > > > -Val > > > > > > On Tue, Apr 18, 2017 at 9:55 AM, Sergi Vladykin < > > sergi.vlady...@gmail.com> > > > wrote: > > > > > > > Val, > > > > > > > > That discussion has nothing to do with this PRIMARY_SYNC problem. > > > > > > > > Sergi > > > > > > > > 2017-04-18 10:51 GMT+03:00 Valentin Kulichenko < > > > > valentin.kuliche...@gmail.com>: > > > > > > > > > Sergi, > > > > > > > > > > I'm talking about this discussion: > > > > > http://apache-ignite-developers.2346864.n4.nabble. > > > > > com/SQL-on-PARTITIONED-vs-REPLICATED-cache-td16478.html > > > > > > > > > > -Val > > > > > > > > > > On Tue, Apr 18, 2017 at 9:46 AM, Vladimir Ozerov < > > voze...@gridgain.com > > > > > > > > > wrote: > > > > > > > > > > > Val, > > > > > > > > > > > > PRIMARY_SYNC doesn't work correctly with the most common case of > > SQL > > > > > query > > > > > > execution over REPLICATED cache. Also it has weird consequences > for > > > > > > continuous queries when coupled with another > > > > performance-over-correctness > > > > > > property "readFromBackup=true": user may receive CQ notification > > with > > > > new > > > > > > value, but subsequent GET on local node may return old value. > > > > > > > > > > > > On Tue, Apr 18, 2017 at 10:42 AM, Valentin Kulichenko < > > > > > > valentin.kuliche...@gmail.com> wrote: > > > > > > > > > > > > > This sounds more like an issue with query execution, rather > than > > > > wrong > > > > > > > PRIMARY_SYNC > > > > > > > behavior. We already had a discussion about this optimization > in > > > > > > replicated > > > > > > > cache and decided to switch it off by default. > > > > > > > > > > > > > > -Val > > > > > > > > > > > > > > On Tue, Apr 18, 2017 at 9:35 AM, Sergi Vladykin < > > > > > > sergi.vlady...@gmail.com> > > > > > > > wrote: > > > > > > > > > > > > > > > With replicated cache we can execute a query against backup > > > > > partitions > > > > > > > that > > > > > > > > were not updated yet because of PRIMARY_SYNC. Thus we do not > > see > > > an > > > > > > > update. > > > > > > > > > > > > > > > > Sergi > > > > > > > > > > > > > > > > 2017-04-18 10:30 GMT+03:00 Dmitriy Setrakyan < > > > > dsetrak...@apache.org > > > > > >: > > > > > > > > > > > > > > > > > Vladimir, > > > > > > > > > > > > > > > > > > What is wrong with a query in PRIMARY_SYNC mode? Why won't > it > > > > work? > > > > > > > > > > > > > > > > > > D. > > > > > > > > > > > > > > > > > > On Tue, Apr 18, 2017 at 12:25 AM, Vladimir Ozerov < > > > > > > > voze...@gridgain.com> > > > > > > > > > wrote: > > > > > > > > > > > > > > > > > > > Folks, > > > > > > > > > > > > > > > > > > > > I received a number of complaints from users that our > > default > > > > > > setting > > > > > > > > > favor > > > > > > > > > > performance at the cost of correctness and subtle > behavior. > > > > > > > Yesterday I > > > > > > > > > > faced one such situation on my own. > > > > > > > > > > > > > > > > > > > > I started REPLICATED cache on several nodes, put some > data, > > > > > > executed > > > > > > > > > simple > > > > > > > > > > SQL and got wrong result. No errors, no warnings. The > > problem > > > > was > > > > > > > > caused > > > > > > > > > by > > > > > > > > > > default PRIMARY_SYNC mode. WTF, our cache doesn't work > out > > of > > > > the > > > > > > > box! > > > > > > > > > > > > > > > > > > > > Another widely known examples are data streamer behavior, > > > "read > > > > > > form > > > > > > > > > > backups" + continuous queries. > > > > > > > > > > > > > > > > > > > > I propose to change our defaults to favor *correctness* > > over > > > > > > > > performance, > > > > > > > > > > and create good documentation and JavaDocs to explain > users > > > how > > > > > to > > > > > > > tune > > > > > > > > > our > > > > > > > > > > product. Proposed changes: > > > > > > > > > > > > > > > > > > > > 1) FULL_SYNC as default; > > > > > > > > > > 2) "readFromBackups=false" as default; > > > > > > > > > > 3) "IgniteDataStreamer.allowOverwrite=true" as default. > > > > > > > > > > > > > > > > > > > > Users should not think how to make Ignite work correctly. > > It > > > > > should > > > > > > > be > > > > > > > > > > correct out of the box. > > > > > > > > > > > > > > > > > > > > Vladimir. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
