Oops, Sorry but I lost part of the discussion that had already been made. Please ignore my previous answer.
Kostas > On Sep 17, 2018, at 4:37 PM, Kostas Kloudas <k.klou...@data-artisans.com> > wrote: > > Hi all, > > Flink does not provide any guarantees about the order of the elements in a > list and it leaves it to the state-backends. > > This means that semantics between different backends may differ, and even if > something holds now for one of them, if > RocksDB or a filesystem decides to change its semantics, then any assumptions > will not hold anymore. > > So I would recommend to program under the assumption that no order guarantees > are provided. > > Cheers, > Kostas > >> On Sep 14, 2018, at 4:30 AM, vino yang <yanghua1...@gmail.com >> <mailto:yanghua1...@gmail.com>> wrote: >> >> Hi Aljoscha, >> >> Regarding window merging, as you said, it's not clear, because Flink does >> some internal work. >> But if it's just for the user, isn't it clear without any internal >> operations? I think if the user explicitly uses it, it should conform to the >> basic List semantics. Otherwise why define it instead of using SetListState >> directly? >> >> Thanks, vino. >> >> Aljoscha Krettek <aljos...@apache.org <mailto:aljos...@apache.org>> >> 于2018年9月13日周四 下午10:42写道： >> Hi, >> >> this is not clearly defined anywhere, and I was always working under the >> assumption that the order is not preserved. This potentially allows more >> optimizations by the system, and for example in case of merging windows we >> don't know the order of elements in a ListState after a merge. >> >> Best, >> Aljoscha >> >>> On 6. Sep 2018, at 08:19, vino yang <yanghua1...@gmail.com >>> <mailto:yanghua1...@gmail.com>> wrote: >>> >>> Hi Alexey, >>> >>> The answer is Yes, which preserves the semantics of the List's order of >>> elements. >>> >>> Thank, vino. >>> >>> Alexey Trenikhun <yen...@msn.com <mailto:yen...@msn.com>> 于2018年9月6日周四 >>> 上午10:55写道： >>> Hello, >>> Does keyed managed ListState<T> preserve elements order, for example if I >>> call listState.add(e1); listState.add(e2); listState.add(e3); , does >>> ListState<T> guarantee that listState.get() will return elements in order >>> they were added (e1, e2, e3) >>> >>> Alexey >>> >>> >> >
