Hi Kannar, Just interested in what exactly your case.
Why do you need to read messages in a reversed order? What is your case? Best, Yong On Mon, 6 Mar 2023 at 23:37, Alexandre DUVAL <kanna...@gmail.com> wrote: > Hi, > > I'm wondering if it is possible to introduce a new feature on Pulsar > which will enable users to read topic from a defined MessageId to > previous messages until the begin of the topic. > > I tried to use Pulsar SQL but it requires so much RAM even for little > queries (due to Presto design). > > Currently, every read in Pulsar are expected to be going forward. So it > might be a bit tricky to prevent every weird behavior by introducing the > feature. > > I'm currently tried to make an MVP/POC by introducting a readReverse > field in the CommandSubscribe that is used by ReaderAPI and currently > looking for to create a getFirstMessageId() on ManagedLedger > (https://github.com/CleverCloud/pulsar/pull/3). I also removed > startPosition < endPosition sanity checks in BookKeeper locally > (https://github.com/CleverCloud/bookkeeper/pull/2). > > We definitely prefer a readPrevious(), hasPreviousMessageAvailable() in > the ReaderAPI. > > I'm not familiar with these internals such as NonDurableCursor, > RangeEntryCache, ManagedCursor so it's a bit tricky. > > So I wondering someone to help/guide me or even directly handle the > subject (or the discuss). > > Regards, > > Kannar > > >
