Andrey, IGNITE-4554 is about compressed bit sets, not standart bit sets.
Currently I'm implementing data structure based on [1] It should efficiently handle sparse bit sets. [1] http://roaringbitmap.org/ 2017-01-21 16:28 GMT+03:00 Sergi Vladykin <[email protected]>: > I'd suggest to have a single abstract class `Partitions` with protected > constructor and static factory method. This will allow to add different > optimized for any particular case implementations transparently. > > Sergi > > 2017-01-21 15:26 GMT+03:00 Andrey Mashenkov <[email protected]>: > > > Hi Guys > > > > Alexei Scherbakov report a ticket few time ago [1]. The solution look > > promissing. > > > > Alexei, you wrote that this can save some memory. More over replacing > > linked Set structure to array based bit-set > > can give a speed-up due to array based structures are cache friendly. > > > > But one thing is not clear for me how we will handle sparsed bit-sets? > For > > example, if we have 1024 partiotions (as it is by default) > > and have much nodes, e.g. 512. In this case, bit-set will occupy 256 > bytes > > that seem to be more than Set<Integer>. > > > > What do you mean exactly to use bit-set as more compact structure then > > Set<Integer> or bit-set with some additional compression? > > > > I would thought, we can use hash-set with open addressing in some cases > > like that to get gain of array bases structures over linked structures > and > > save memory? > > For example, we could use such hash-set for small data (64bytes as cache > > line size) and use bit-sets for bigger data, if it's possible of course. > > > > > > Thoughts? > > > > [1] https://issues.apache.org/jira/browse/IGNITE-4554 > > > -- Best regards, Alexei Scherbakov
