[Clickhouse] Too many simultaneous queries

1 Overview

According to the flink clickhouse sink of Git: https://github.com/ivi-ru/flink-clickhouse-sink.git
, this method is written in http, so there will be some problems with writing.

First explain

1. ck's http interface, not only can write data, but also a port used to query data
2. The tcp interface of ck is stateless and the write rate is very fast

At present, I have only found a way to write to flink http. TCP did it by myself. The speed is really fast, but I haven't found how to support json format insertion.

When I tested, I increased the write rate, which caused the write and query to exceed the limit, as follows.

The operation of the live network environment suddenly appears:DB::Exception: Too many simultaneous queries. Maximum: 200

The reason for the problem should be that a large amount of data is stored in the database, which causes the tree merge frequency to be too high, the query speed decreases, and there are many slow queries.

ease