Thanks Xiaoxiang,
Very good questions! Please see my comments started with [Gang]:


1.      Is it possible to use Yarn as cluster manager for index task. 
Coordinator process will set up them at specificed period. 
[Gang] I think it is possible, but in current design,  the indexing task is 
designed as long running task, it also can provide query service, this makes 
the whole system very simple and efficiency, I don't think we need to 
stop/start indexing task time by time. But use yarn to manage the resource is 
possible, we need to redesign the existing coordinator, to make it easy to 
deploy to Yarn, Kubernetes, etc. Hope this can be done after contribution to 
community.

2.      As I know, ebay’s New Kylin Streaming Solution use replica Set to 
ensure that income messages wouldn’t lost if some processes  lost. I think 
replica set is a set of kafka cosumer processes which is responsible for ingest 
message and build base cuboid in memory. Could you please show me some detail 
about how replica Set provide HA guarantee? How to configure it? A link / paper 
is OK.  I found one but I don’t know if it same meaning for your replica Set.


[Gang] Yes, it is similar as the MongoDB replication, but currently we don't 
replicate data from Primary node, just assign the same Kafka topic/partitions 
to the receivers in a ReplicaSet, all receivers in a ReplicaSet will consume 
data from Kafka, so if one receiver is down, other receivers in the ReplicaSet 
are still consuming the same Kafka data, so the consume/query will not be 
impact. And We don't guarantee that the receivers in a ReplicaSet have the same 
consuming rate, but we can guarantee that the user can view data consistently 
by stick to the query to one receiver for one cube. 
The HA implementation is a little bit naive, but simple and worked. Maybe in 
the future, we can do HA by replication to support other streaming sources that 
don't support multiple consumers and don't have persistent store.

3.      How to add or remove node of replica Set in production env? How to 
monitor the health/pressure of replica Set cluster ?
[Gang] Currently we have UI/restful api to let admin to add/remove node to/from 
a ReplicaSet, and have a simple ui to let admin monitor the health, consuming 
rate for each receiver/cube. Also all metrics are collected using yammer 
metrics framework, it is easy to exposed to other monitor system.

4.      Does all measure are supported in ebay’s New Kylin Streaming Solution? 
What about count distinct(bitmap)?
[Gang] Most measures are supported, but precise count distinct(bitmap) is not 
support in case that the distinct dimension is not int type. As you know, to 
support precise count distinct for not-int type dimension, it needs to build 
global dictionary, it is not possible in the streaming env.


5.      It seems ebay’s New Kylin Streaming Solution use a custom columnar 
storage, why not use a open source mature columnar storage  solution ? Have 
your ever compare the performance of your custom columnar storage to open 
source columnar storage  solution ?

[Gang] Most open source columnar format like Parquet, ORC are designed to use 
in Hadoop env, the streaming data are in local disk, so I didn't consider them 
at the beginning. It is not very hard to define columnar format to store Kylin 
specific data, use a customize columnar storage, you can use mmap file to scan 
data, add row-level invert index for all dimensions, so I think the performance 
will be better compared to using common columnar format. I didn't compare the 
performance, but the storage engine is pluggable, you may contribute a parquet 
storage if you are interesting.






At 2018-11-01 12:42:25, "Xiaoxiang Yu" <xiaoxiang...@kyligence.io> wrote:
>Hi gang, I am so glad to know that eBay has a solution for realtime olap on 
>kylin. I have some small question:
>
>
>1.      Is it possible to use Yarn as cluster manager for index task. 
>Coordinator process will set up them at specificed period. Yarn will manage :
>
>a)       retry these task if some failed
>
>b)       resource allocation
>
>c)       log collection
>
>2.      As I know, ebay’s New Kylin Streaming Solution use replica Set to 
>ensure that income messages wouldn’t lost if some processes  lost. I think 
>replica set is a set of kafka cosumer processes which is responsible for 
>ingest message and build base cuboid in memory. Could you please show me some 
>detail about how replica Set provide HA guarantee? How to configure it? A link 
>/ paper is OK.  I found one but I don’t know if it same meaning for your 
>replica Set.
>
>a)       [Mongodb replication](https://docs.mongodb.com/manual/replication/).
>
>3.      How to add or remove node of replica Set in production env? How to 
>monitor the health/pressure of replica Set cluster ?
>
>4.      Does all measure are supported in ebay’s New Kylin Streaming Solution? 
>What about count distinct(bitmap)?
>
>5.      It seems ebay’s New Kylin Streaming Solution use a custom columnar 
>storage, why not use a open source mature columnar storage  solution ? Have 
>your ever compare the performance of your custom columnar storage to open 
>source columnar storage  solution ?
>
>
>
>----------------
>Best wishes,
>Xiaoxiang Yu
>
>
>发件人: Ma Gang <mg4w...@163.com>
>答复: "dev@kylin.apache.org" <dev@kylin.apache.org>
>日期: 2018年10月30日 星期二 15:24
>收件人: "dev@kylin.apache.org" <dev@kylin.apache.org>
>主题: [DISCUSS] New Kylin Streaming Solution From eBay
>
>Hi all,
>
>eBay Kylin team has developed a new Kylin streaming solution, the basic idea 
>is to build a streaming cluster to ingest data from streaming source(Kafka), 
>and provide query for real-time data, the data preparation latency is 
>milliseconds, which means the data is queryable almost when it is ingested, 
>attach is the architecture design doc.
>We would like to contribute the feature to community, please let us know if 
>you have any concern.
>
>Thanks,
>Gang(Allen) Ma
>
>
>
>
>

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