Feature Request

Is your feature request related to a problem? Please describe:

This is a really minor nit, but the EXPLAIN output on binary strings is different from what I expected:

CREATE TABLE t1 (
 id INT NOT NULL PRIMARY KEY auto_increment,
 b varchar(255) not null,
 c varbinary(255) not null,
 index (b),
 index (c)
);


INSERT INTO t1 (b,c) VALUES ('a', 'a'),('b

Throw NullPointException when INSERT column and values mismatch.
It is better to throw suitable SQLException for JDBC-driver and proxy.

The tasks are:

• Throw suitable SQLException for JDBC-driver.
• Report suitable error packet with MySQL proxy.
• Report suitable error packet with PostgreSQL proxy.

Bug Report

What version of TiKV are you using?

I think the description of config max-tasks-per-worker-high in the document is wrong:https://github.com/tikv/tikv/blob/master/docs/V2.1/op-guide/coprocessor-config.md#max-tasks-per-worker-high
https://github.com/tikv/tikv/blob/master/docs/refer

我看到可以通过Prometheus搭建监控环境，如果有图文，更容易理解．

Just tried installing the client (3.12.2) with our app, and it's crashing trying to do sql queries. Sequelize is version 3.30.4, Mysql is version 2.13.0.

TypeError: Cannot read property 'setMaxListeners' of undefined
at [...] node_modules/sequelize/lib/dialects/mysql/query.js:53:7
at Promise.cancellationExecute [as _execute] ([...] node_modules/bluebird/js/release/debuggability.js:32