sijie commented on issue #774: Open should run recovery by default URL: https://github.com/apache/bookkeeper/pull/774#issuecomment-346891627 @ivankelly as I said in my previous comment, I am -0 for this. that means I wouldn't block the change making recovery as default. I don't like splitting the builder into two. the different views on LAC exactly reflects the views on how bookkeeper would look like and can be used for. LAC is not an optimization (it might be an optimization when you guys initially developed it for hdfs namenode). However, LAC is the most beautifully thing when you comes from streaming and tailing world. And it is the key differentiator how bookkeeper is different from a traditional storage system like filesystem, blobstore. LAC is the mechanism for propagating how your length of a stream grow and provides the consistency boundary for simple repeatable read consistency. while fencing and recovery can't. fencing and recovery are the mechanism for preventing split brain, which is more on writer side. Many other storage systems have fencing and recovery mechanism. It is just a way to prevent split brain. They might do it in many different ways. However in a bytes-orient storage system, like blob store, filesystem, you can't have LAC. LAC is unique to bookkeeper, because it is record-orient storage system. LAC makes bookkeeper so unique for streaming and tailing. That is something I would like us to emphasize and educate people to use bookkeeper. The reason why do you think fencing and recovery is cool in bookkeeper, is exactly because the way how you use bookkeeper. Most of the use cases like hdfs namenode, hedwig, pulsar are only use bookkeeper for writes. You need fencing and recovery to prevent split brain when ownership or leadership change. But this category of use cases is so limited. in distributedlog, at Twitter, we use bookkeeper in a lot of streaming and tailing use cases, where LAC is the soul. It guarantees TOAB and simple repeatable consistency while you do streaming and tailing. That's where bookkeeper is so unique from other storage systems. If we want bookkeeper to grow into a large community, we have to educate people in a way that people will realize this uniqueness.
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