Good questions:
*I agree that `auto.offset.reset="earliest"` would be a better default. However, I am a little worried about backwardcompatibility. * Keep in mind that existing mirrormaker instances will *not* be affected for topics they are currently consuming because they will already have saved offsets. This will only affect mirrormakers that start consuming new topics, for which they don't have a saved offset. In those cases, they will stop seeing data loss when they first start consuming. My guess is the majority of those new topics are going to be newly-created topics anyway, so most of the time starting from the earliest simply prevents skipping the first few seconds/minutes of data written to the topic. *What I am also wondering thought is, does this only affect MirrorMaker or also MirrorMaker 2? * I checked and MM2 already sets `auto.offset.reset = 'earliest'` <https://github.com/apache/kafka/blob/d63eaaaa0181bb7b9b4f5ed088abc00d7b32aeb0/connect/mirror/src/main/java/org/apache/kafka/connect/mirror/MirrorConnectorConfig.java#L233> . *Also, is it worth to change MirrorMaker now that **MirrorMaker 2 is available?* Given that it's 1-line of code, doesn't affect existing instances, and prevents data loss on new regex subscriptions, I think it's worth setting... I basically view it as a bugfix rather than a feature change. I realize MM1 is deprecated, but there's still a lot of old mirrormakers running, so flipping this now will ease the future transition to MM2 because it brings the behavior of MM1 in line with MM2. Thoughts? On Sat, Apr 11, 2020 at 11:59 AM Matthias J. Sax <mj...@apache.org> wrote: > Jeff, > > thanks for the KIP. I agree that `auto.offset.reset="earliest"` would be > a better default. However, I am a little worried about backward > compatibility. And even if the current default is not idea, users can > still change it. > > What I am also wondering thought is, does this only affect MirrorMaker > or also MirrorMaker 2? Also, is it worth to change MirrorMaker now that > MirrorMaker 2 is available? > > > -Matthias > > > On 4/10/20 9:56 PM, Jeff Widman wrote: > > > https://cwiki.apache.org/confluence/display/KAFKA/KIP-592%3A+MirrorMaker+should+replicate+topics+from+earliest > > > > It's a relatively minor change, only one line of code. :-D > > > > > > > > -- *Jeff Widman* jeffwidman.com <http://www.jeffwidman.com/> | 740-WIDMAN-J (943-6265) <><
