The atomic sequence/long could be persisted if the default data region is persistent[1]. One of the use cases for IgniteAtomicSequence is to generate unique IDs. You could estimate the volume implicitly by getting metrics from the default data region[2].
[1] https://ignite.apache.org/docs/latest/persistence/native-persistence#enabling-persistent-storage [2] https://apacheignite.readme.io/v2.8.0/docs/memory-metrics#getting-metrics вт, 27 окт. 2020 г. в 21:50, narges saleh <[email protected]>: > Questions: > I know I should take into account the cluster size and the data volume, > but how bad is the overhead of IgniteAtomicLong? Any benchmarking? > What are the use cases for IgniteAtomicSequence if it does not > guarantee ordering? > > thanks. > > On Tue, Oct 27, 2020 at 10:27 AM narges saleh <[email protected]> > wrote: > >> Thank you Pavel, for the information. >> >> What happens to the atomic sequence/long value in case of a system >> restart? Do I need to persist the value somewhere and pass it as the >> initial value, across cluster restarts? >> >> On Tue, Oct 27, 2020 at 1:13 AM Pavel Vinokurov < >> [email protected]> wrote: >> >>> Hi, >>> >>> In case of rebalance the reserves aren't recalculated. So the next >>> values will be in the range [1001,1000+reserveSize]. >>> After the local reserve exceeds, the node reserves a new range >>> starting from the global last sequence number. >>> The main idea IgniteAtomicSequence is to generate unique numbers but it >>> doesn't guarantee ordering. >>> If you need ordering you could set the reserve size to 1 or use >>> IgniteAtomicLong. >>> >>> Thanks, >>> Pavel >>> >>> вс, 25 окт. 2020 г. в 05:00, narges saleh <[email protected]>: >>> >>>> Hi All, >>>> What is the consequence of data rebalancing across nodes as far as >>>> IgniteAtomicSequence and the reserve on each node is concerned? For >>>> example, if the last sequence number is 6000 in one node and the record >>>> moves to a node whose last sequence number is 1000? Do the reserves on both >>>> nodes get recalculated? >>>> >>>> Are there best practices for generating and using these sequences? >>>> >>>> Is IgniteAtomicSequence the right approach if I want to keep track of >>>> the records on each node for a partitioned cache? >>>> >>>> thanks. >>>> >>> >>> >>> -- >>> >>> Regards >>> >>> Pavel Vinokurov >>> >> -- Regards Pavel Vinokurov
