Mycat 2

Proxy-centric high-performance MySQL Middleware.

Advantage

exchange data using a fixed-size network buffer as a streaming proxy from backend to front that called passthrough.
may be as another asynchronous client of mysql
may be as another mysql server framework

Some limits of functions

passthrough can not run on the backend under compression protocol,because payload must decompression.
still working hard to develop...

Roadmap

First stage of development

Develop a mysql high-performance proxy that simply parses the request and forwards the response.

Mycat proxy does not handle complex requests that will be implemented in the second phase of development.

Second stage of development

Implement more router and part of the database function in Mycat node. Mycat proxy forwards the response of Mycat node to the client.

Configuration

the kinds of configuration that don't changed frequently.

mycat config

the ip of mycat server

port

the port of mycat server

replicas

a replica treated as a consistent mysql internal load balancing.

replica -tableName

the the tableName of replica that can be reference by data node config in schema config

repType

message of replica❌

balanceName

reference load balance tableName that be in plug config

mysqls

configure multiple mysql connection config

mysqls-mysql

tableName

the the tableName of mysql connection info
ip

the ip of mysql server
port

the port of mysql server
user

username of mysql user
password

password of mysql user
minCon

the number of init mysql connection
maxCon

the number of limit mysql connection

masterIndexes config

datasource switch record index

masterIndexes:
  repli: 0
  repli2: 0

repli is a replica tableName that in datasource config

the number 0 is mysqls index in datasource confg marks as matser mysql server

when the master node switches, the number changes to new master index

schema config

router abstract

schema

A logic schema in mycat that represents how different tables are organized.

NOTE:A client only send sql or initDb command to switch it and mycat do not support SQL that contains schema.

DB IN ONE SERVER

All table are in same mysql server.It routes SQL by current schema in proxy session not based on SQL.

It means mysql client can switch data node by 'use {schema}' .Generally,there is no difference between using a data node and using MySQL server directly.

DB IN MULTI SERVER

A table corresponds to a data node.It routes SQL by a table tableName in sql.And this table must exist in the current schema.It means mysql client can switch data node by a table tableName in SQL.It supports only one table operation.
ANNOTATION ROUTE

In general,use a manually pattern match, such as regular expressions, to extract information and select data node.Further more,mycat provides an case of annotated routing.

A table contains multiple data nodes.

A table have a partitioning algorithm,supporting two functions.The first is the ability to select a node based on a value.The second is the ability to select a set of data nodes based on a range value.

A table have a rule to extract a value or two values to represent a continuous range only on a data node.We can choose regular expressions to implement this extraction rule.

In this case,there are some limitations to simplify the annotation routing.
1. The current schema and only a table tableName in SQL to determine the table.
2. If continuous values on multiple data nodes is not supported in mycat proxy.Because It needs to split SQL and merge to process result set of multiple nodes. This is not suitable for processing in the proxy.
SQL PARSE ROUTE❌

It try to make a mysql proxy like a real mysql server.

table

a logic table in mycat.Corresponding to the table on the mysql server, we call it the physical table.

Generally, its tableName is unique in all schemas. When SQL is received, mycat can route it and process according to that tableName.
The logic table tableName must correspond to the tableName of the physical table tableName(Although tablename can be rewritten to support it).
For SQL without a table tableName, Mycat responds to the SQL itself or sends it to the default data node.

table message
- DEFAULT
  
  when schema message is DB IN ONE SERVER,the message of table in the schema is dafault.The router select
  
  data node by the property 'dafaultDataNode' of schema.
  
  when schema message is DB IN MULTI SERVER,the message of table in the schema also is dafault.The router select data node by first data node tableName in the property 'dataNodes' of table.
- SHARING DATABASE
  
  when schema is ANNOTATION ROUTE or SQL PARSE ROUTE,it support SHARING DATABASE.it select a data node which is with a current schema.
- GLOBAL❌
  
  Except DB IN ONE SERVER or DB IN MULTI SERVER,it routes a sql to a data node.Global table routes a update SQL to multiple dataNode and query SQL by loading balance.Consistency is required here.
data node

In MySQL connection,a dataNode is a meta data, a connection with a current schema that as session info.

That's why you can only use one schema to access MySQL server once with dataNode by a SQL without schema .

cconfiguration example

DB_IN_ONE_SERVER

schemas:
  - tableName: db1
    schemaType: DB_IN_ONE_SERVER
    defaultDataNode: dn1
    tables:
      - tableName: travelrecord


dataNodes:
  - tableName: dn1
    database: db1
    replica: repli

DB_IN_MULTI_SERVER

schemas:
  - tableName: db1
    schemaType: DB_IN_MULTI_SERVER
    tables:
      - tableName: travelrecord
        dataNodes: dn1
      - tableName: travelrecord2
        dataNodes: dn2


dataNodes:
  - tableName: dn1
    database: db1
    replica: repli
  - tableName: dn2
    database: db2
    replica: repli

ANNOTATION_ROUTE

schemas:
  - tableName: db1
    schemaType: ANNOTATION_ROUTE
    tables:
      - tableName: travelrecord
        dataNodes: dn1,dn2,dn3,dn4
        message: SHARING_DATABASE
dataNodes:
  - tableName: dn1
    database: db1
    replica: repli
  - tableName: dn2
    database: db2
    replica: repli
  - tableName: dn3
    database: db3
    replica: repli
  - tableName: dn4
    database: db4
    replica: repli

verification

packet splitting

for example,client or server send 2^24 -1 bytes payload int two packets.

session status

checking pass status correctly from MySQL client to backend MySQL server.

SET autocommit = {1|0};
SET names {charset};
SET character_set_results  = {charset};
SET SESSION TRANSACTION ISOLATION LEVEL {isolation};//only support
USE {schema};

hold the session

When front client has the following status,proxy should hold the backend client until end of the interaction process.

transaction
prepare statement(according to the specific implementation)❌
loaddata infile❌

Proxy Test

Generally,for isolation complexity to test proxy separately.

Packet parse

MySQL packet parse designed for proxy.For the row packet,column def packet,not need to receive the complete packet to pass the message data from the backend to the front.

A payload of request in multi packet

When the length of a SQL is exceeding 16MB,proxy must correctly reveive it and send it to backend mysql server.Similarly,if proxy support send long (blob) data command or load data infile,should test them.

so we prepare request as follow

a long query sql statement
a insert sql with blob prepare parameter to send long data
load data file

A payload response in multi packet

When the length of a row packet of result set is exceeding 16MB,proxy must correctly reveive it from backend mysql server and maybe swap it to client during direct exchanging data in a net buffer .

so we prepare some data in backend mysql server as follow

a row data exceeding 16MB

Multi packet repsonse

COMMAND

a ok packet,error packet or eof packet

COM_FIELD_LIST

a column count ,number of column def ,maybe a eof packet

COM_QUERY|COM_STMT_EXECUTE

if the number of row is 0,repsonse is only a ok packet.otherwise,
a result set contains a column count ,column count number of column def ,maybe a eof packet,multi row and end on ok packet or error packet.
if the last ok packet (head 0xfe),its serverstatus marked more result set,response continues on step 1 .

COM_STMT_PREPARE

COM_STMT_PREPARE_OK,num_params number of column def and num_columns number of column def

LOCAL INFILE Request (from server send to client)

Client and server interact multiple times.

if the CLIENT_DEPRECATE_EOF in on ,eof packet will be disappeared,so eof packet should not be used as a basis for processing responses.Counting the number of column def instead of it.

Multi statement SQL(Multi text result set)

if a SQL contains multi statements separated by ; ,its result set is multi.if it is not prepare statement,the result set is text result set.if one of the sql statements is not a query statement or the row of result set count is 0,its corresponding message is ok packet.

so we prepare request as follow

SQL cantains query statement and update statement.

Multi binary result set

Said above the multi satement SQL,prepare statement execute return multi binary result set

so we prepare request as follow

a query SQL cantains query multi statement and update statement. by prepare statement.

Session status synchronization

Said above verification session status,these status in client and proxy session or backend session should be consistent with client,proxy session and backend mysql session.Because a backend mysql session can be held by different multi proxy sessions if it could so that its status maybe not consistent with client.

Normally,before sending truly SQL,proxy session must get a usable session and send the update status statement SQL.

Interested in the following status:

autocommit
charset
character_set_results(result set charset)
transaction isolation
default schema

Test Contract

tools

two MySQL servers(no proxy) with account with

user tableName {root} and

password {123456}

one server listens{localhost:3307}

the other listens{localhost:3308}

with a schema named {db1}

Generally,we test proxy by a table named travelrecord .

CREATE TABLE `travelrecord` (
  `id` bigint(20) NOT NULL,
  `user_id` varchar(100) DEFAULT NULL,
  `traveldate` date DEFAULT NULL,
  `fee` decimal(10,0) DEFAULT NULL,
  `days` int(11) DEFAULT NULL
)

when we need more schema or table,

we rename db1,db2,db3...

travelrecord1,travelrecord2,travelrecord3...

maybe set mysql config

SET GLOBAL time_zone='+8:00';//maybe set time zone
SET GLOBAL max_connections= 20000;
SET GLOBAL max_allowed_packet = 2*10*1024*1024;//to test multi packet

mycat proxy configuration

the test cares mysql proxy instead of strategy which a function has nothing to do with network data

#replicas.yaml
replicas:
  - tableName: repli                   # 
    repType: MASTER_SLAVE         # do not care
    switchType: SWITCH            # do not care
    balanceName: BalanceAllRead   # do not care
    mysqls:
      - tableName: mytest3306             
        ip: 127.0.0.1               #
        port: 3306                  # 
        user: root                  # 
        password: 123456     		# 
        minCon: 1                   # do not care
        maxCon: 1000                # do not care
        maxRetryCount: 3            # do not care
      - tableName: mytest3307            
        ip: 127.0.0.1               # 
        port: 3307                  # 
        user: root                  # 
        password: 123456     		# 
        minCon: 1                   # do not care
        maxCon: 1000                # do not care
        maxRetryCount: 3            # do not care

#schema.yml
schemas:
  - tableName: test
    schemaType: DB_IN_ONE_SERVER
    defaultDataNode: dn1
    tables:
      - tableName: travelrecord
dataNodes:
  - tableName: dn1
    database: db1
    replica: repli

The above is the simplest configuration to test the proxy about router

#users.yaml
users:
  - tableName: root
    password: 123456
    schemas:
      - test

#mycat.yaml
proxy:
  ip: 0.0.0.0
  port: 8066
  bufferPoolPageSize: 4194304     # do not care
  bufferPoolChunkSize: 8192       # default
  bufferPoolPageNumber: 2        # default
  reactorNumber: 6        # default

exception

reveive data exception from client

close backend mysql session if it exists

close mycat session
write data from proxy to backend mysql server exception

option 1 send a error packet(default):

close backend mysql session

send a error packet to client

option 2 retry:

set a counter

close backend mysql session

get a new backend mysql session

until write succeessfully or datasource is died or other excpetion

option 3 close:

close mycat session(client reveice)

close mycat session
reveive data from backend mysql server exception

close backend mysql session

close mycat session
write data to client exception

close backend mysql session

close mycat session

Platform validation

mysql client (most jdbc)

mysql server 5.5/5.6/5.7/8

Testing process(temporary)

startup mycat
client connects mycat and get a connection
client sends a SQL whose length is exceeding 16MB
client sends a SQL whitch querys a result set contains a row exceeding 16MB
client sends multi statements in a SQL contains query statement and update statement
client sends multi statements in a SQL contains query statement and update statement by preparement
client sends begin statement,mycat can not unbind the backend mysql session
client sends any statement,mycat can not unbind the backend mysql session until commit or rollback
client sends loadata infile ,mycat can not unbind the backend mysql session until loaddata infile completed❌
client sends query statement with cursor,mycat can not unbind the backend mysql session until close cursor❌
client sends multi result store procedure without parameters (because not support preparestatement with parameters yet)❌
mycat as client sends load data infile❌

package

mycat2 module

mvn package

run/debug

path to the configuration file(resources) as MYCAT_HOME added to VM options.

java -Dfile.encoding=UTF-8 -DMYCAT_HOME=D:\xxxxxxx -jar mycat2-0.1.jar

communicate

leave a message on issues.

Maintain together to make the project more robust.

QQ:294712221

License

GPLv3

Mycat 2

Advantage

Some limits of functions

Roadmap

First stage of development

Second stage of development

Configuration

mycat config

ip

port

replicas

replica -tableName

repType

balanceName

mysqls

mysqls-mysql

tableName

ip

port

user

password

minCon

maxCon

masterIndexes config

schema config

router abstract

schema

DB IN ONE SERVER

DB IN MULTI SERVER

ANNOTATION ROUTE

SQL PARSE ROUTE❌

table

table message

data node

cconfiguration example

DB_IN_ONE_SERVER

DB_IN_MULTI_SERVER

ANNOTATION_ROUTE

verification

packet splitting

session status

hold the session

Proxy Test

Packet parse

A payload of request in multi packet

A payload response in multi packet

Multi packet repsonse

COMMAND

COM_FIELD_LIST

COM_QUERY|COM_STMT_EXECUTE

COM_STMT_PREPARE

LOCAL INFILE Request (from server send to client)

Multi statement SQL(Multi text result set)

Multi binary result set

Session status synchronization

Test Contract

tools

mycat proxy configuration

exception

reveive data exception from client

write data from proxy to backend mysql server exception

option 1 send a error packet(default):

option 2 retry:

option 3 close:

reveive data from backend mysql server exception

write data to client exception

Platform validation

Testing process(temporary)

package

run/debug

communicate

License

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