Apache Druid

you can use some CDC tool to import into kafka, then ingest in 'real-time'

there's also some option to import via jdbc_connector, but there's always some issues doing that way

Druid is opinionated when it comes to ingestion.
Maybe one day, when multi-stage-query is matured enough, it can ingest directly using SQL.

<https://druid.apache.org/docs/latest/ingestion/native-batch-input-sources.html#sql-input-source> - This might work too

Thanks for your responds.
My point is why we have to push data to csv or tsv first then indexing them?
<@U031A9D19NU> it is great to have this new solution now. But, this tool still will store data into disk then it will read data from local disk on druid to segment them. The following phrase from druid documentation:
&gt; During indexing, each sub-task would execute one of the SQL queries and the results are stored locally on disk. The sub-tasks then proceed to read the data from these local input files and generate segments.

all batch ingestion do generate intermediate data though some thinking will be needed to write a list of queries that lets you parallelize the execution.