Hi Jason and Colin, Thanks for the feedback. I agree that having filtering support to the Metadata API would be useful and solves the scalability issues.
But to implement specific use case of "describe all topics", regex support won't help. In any case user needs to call listTopics() to get topic list, and then make describeTopics() calls with a subset of the topics set. This leads to improving existing listTopics() API performance. Colin already raised a KIP for this: KIP-142 <https://cwiki.apache.org/confluence/display/KAFKA/KIP-142%3A+Add+ListTopicsRequest+to+efficiently+list+all+the+topics+in+a+cluster> . May be we should consider implementing KIP-142. Since we have support wildcard ACLs, Initially, I can explore prefixed/wildcards patterns support to Metadata API. We can later extend support for regular expressions. Thanks On Sat, Jul 14, 2018 at 2:42 PM Ted Yu <yuzhih...@gmail.com> wrote: > What if broker crashes before all the pages can be returned ? > > Cheers > > On Sat, Jul 14, 2018 at 1:07 AM Stephane Maarek < > steph...@simplemachines.com.au> wrote: > > > Why not paginate ? Then one can retrieve as many topics as desired ? > > > > On Sat., 14 Jul. 2018, 4:15 pm Colin McCabe, <cmcc...@apache.org> wrote: > > > > > Good point. We should probably have a maximum number of results like > > > 1000 or something. That can go in the request RPC as well... > > > Cheers, > > > Colin > > > > > > On Fri, Jul 13, 2018, at 18:15, Ted Yu wrote: > > > > bq. describe topics by a regular expression on the server side > > > > > > > > Should caution be taken if the regex doesn't filter ("*") ? > > > > > > > > Cheers > > > > > > > > On Fri, Jul 13, 2018 at 6:02 PM Colin McCabe > > > > <cmcc...@apache.org> wrote:> > > > > > As Jason wrote, this won't scale as the number of partitions > > > > > increases.> > We already have users who have tens of thousands of > > > topics, or > > > > > more. If> > you multiply that by 100x over the next few years, you > > > end up with > > > > > this API> > returning full information about millions of topics, > > which > > > clearly > > > > > doesn't> > work. > > > > > > > > > > We discussed this a lot in the original KIP-117 DISCUSS thread > > > > > which added> > the Java AdminClient. ListTopics and DescribeTopics > > > were > > > > > deliberately kept> > separate because we understood that > eventually a > > > single RPC would > > > > > not be> > able to return information about all the topics in the > > > cluster. So > > > > > I have> > to vote -1 for this proposal as it stands. > > > > > > > > > > I do agree that adding a way to describe topics by a regular > > > > > expression on> > the server side would be very useful. This would > > > also fix a major > > > > > scalability problem we have now, which is that when > > > > > subscribing via a> > regular expression, clients need to fetch the > > > full list of all > > > > > topics in> > the cluster and filter locally. > > > > > > > > > > I think a regular expression library like re2 would be ideal > > > > > for this> > purpose. re2 is standardized and language-agnostic > (it's > > > not tied > > > > > only to> > Java). In contrast, Java regular expression change with > > > different > > > > > releases> > of the JDK (there were some changes in java 8, for > > > example). > > > > > Also, re2> > regular expressions are linear time, never exponential > > > time. See > > > > > https://github.com/google/re2j > > > > > > > > > > regards, > > > > > Colin > > > > > > > > > > > > > > > On Fri, Jul 13, 2018, at 05:00, Andras Beni wrote: > > > > > > The KIP looks good to me. > > > > > > However, if there is willingness in the community to work on > > > > > > metadata> > > request with patterns, the feature proposed here > and > > > filtering by > > > > > > '*' or> > > '.*' would be redundant. > > > > > > > > > > > > Andras > > > > > > > > > > > > > > > > > > > > > > > > On Fri, Jul 13, 2018 at 12:38 AM Jason Gustafson > > > > > > <ja...@confluent.io>> > wrote: > > > > > > > > > > > > > Hey Manikumar, > > > > > > > > > > > > > > As Kafka begins to scale to larger and larger numbers of > > > > > topics/partitions, > > > > > > > I'm a little concerned about the scalability of APIs such as > > > > > > > this. The> > API > > > > > > > looks benign, but imagine you have have a few million > > > > > > > partitions. We> > > > already expose similar APIs in the > producer > > > and consumer, so > > > > > > > probably> > not > > > > > > > much additional harm to expose it in the AdminClient, but it > > > > > > > would be> > nice > > > > > > > to put a little thought into some longer term options. We > should > > > > > > > be> > giving > > > > > > > users an efficient way to select a smaller set of the topics > > > > > > > they are> > > > interested in. We have always discussed adding > > > some filtering > > > > > > > support> > to > > > > > > > the Metadata API. Perhaps now is a good time to reconsider > this? > > > > > > > We now> > > > have a convention for wildcard ACLs, so perhaps > we > > > can do > > > > > > > something> > > > similar. Full regex support might be ideal > given > > > the consumer's> > > > subscription API, but that is more challenging. > > What > > > do you > > > > > > > think?> > > > > > > > > > > Thanks, > > > > > > > Jason > > > > > > > > > > > > > > On Thu, Jul 12, 2018 at 2:35 PM, Harsha <ka...@harsha.io> > > wrote:> > > > > > > > > > > > > > > Very useful. LGTM. > > > > > > > > > > > > > > > > Thanks, > > > > > > > > Harsha > > > > > > > > > > > > > > > > On Thu, Jul 12, 2018, at 9:56 AM, Manikumar wrote: > > > > > > > > > Hi all, > > > > > > > > > > > > > > > > > > I have created a KIP to add describe all topics API to > > > > > > > > > AdminClient> > . > > > > > > > > > > > > > > > > > > https://cwiki.apache.org/confluence/display/KAFKA/KIP- > > > > > > > > 327%3A+Add+describe+all+topics+API+to+AdminClient > > > > > > > > > > > > > > > > > > Please take a look. > > > > > > > > > > > > > > > > > > Thanks, > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
