Hi Yong,
The goal is to start from a known MessageId and read the N message
before this MessageId.
Best,
Kannar
On 3/7/23 01:53, Yong Zhang wrote:
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
--
*Alexandre DUVAL*
@KannarFR
/+33 6 12 97 19 70/
