slackerdb: 使用标准PostgresSQL通讯协议封装DuckDB，使得DuckDB可以支持多人并发访问、查询、更新。也可以通过TCPIP协议访问。

![机器人小懒](robotslacker.jpg)

# SlackerDB (DuckDB Postgres proxy)

## Quick Note
This is an agile DuckDB extension that provides Java-based connectivity with network access and multi-process support capabilities.

### What we can do:
Based on the description, this tool achieves the following capabilities:

* Enables remote access to DuckDB via TCP/IP from multiple locations, instead of local-only limitations. 
* Supports multi-process access to DuckDB instead of single-process restrictions. 
* Provides PostgreSQL wire protocol compatibility (JDBC, ODBC, etc.), allowing DuckDB to function like a PostgreSQL database.
* Offers a dedicated access client within the tool that delivers:
  1. Advanced features
  2. Comprehensive data dictionary access support
* You can use COPY syntax to quickly import data, compatible with PG's CopyManager.

You have multiple ways to connect to our database:
*  Directly connect to the server
*  Connect through a proxy. Based on the proxy, you can connect to multiple servers through one proxy.
*  Connect through the WEB Service (to be implemented)
*  Embed the compiled jar package into your own application, so you don't need a separate database service program.

## Usage
### Build from source:
```
    # Download JDK17 and maven 3.6+, and install them.
    # Download source code
    git clone ...
    # compile it
    cd slackerdb
    mvn clean compile package
    
    # All compiled results will be placed in the dist directory.
    #    compiled Jar packages, 
    #    default configuration files.
```

### Start db server
``` 
    java -jar dbserver/target/slackerdb-dbserver-0.1.5-standalone.jar start
```
### Stop db server
``` 
    java -jar dbserver/target/slackerdb-dbserver-0.1.5-standalone.jar stop
```
### Check db status
``` 
    java -jar dbserver/target/slackerdb-dbserver-0.1.5-standalone.jar status
```
### Start db proxy
``` 
    java -jar dbproxy/target/slackerdb-dbproxy-0.1.5-standalone.jar start
```
### Stop db proxy
``` 
    java -jar dbproxy/target/slackerdb-dbproxy-0.1.5-standalone.jar stop
```
### Check proxy status
``` 
    java -jar dbproxy/target/slackerdb-dbproxy-0.1.5-standalone.jar status
```

### Server configuration file template
``` 
# Database name
data=slackerdb

# Path where data files are saved
# Empty means it is placed in memory (i.e.: memory:) , after db restart, all data will lost.
data_dir=:memory:

# The location of temporary files during database operation.
# Disk mode:   If not set, it defaults to the same as data_dir.
# Memory mode: If not set, it defaults to system temporary setting.
# It is strongly recommended to use a high-performance disk as a temporary directory.
temp_dir=

# Location of system extension plugin files.
# If not set, it defaults to $HOME/.duckdb/extensions
extension_dir=

# Whether the program is started in the background. If true, it will run in the background
daemonMode=

# PID file. Used to describe the process id of running server process.
# When server is running, the file will be exclusively locked.
# If this file is locked by other process, server will abort and not continue start.
# If not configured, this file will not be generated and the lock will not be checked.
pid=

# The location where the log file is saved
# CONSOLE means output to the console, and others mean output to a file
# Multiple logs can be output at the same time, separated by commas, for example, “console, logs/xx.log”
log=CONSOLE,logs/slackerdb.log

# Log level
log_level=INFO

# Service port
# 0 means the system will randomly assign a port
# -1 means no port will be opened
# default is 0, means random port.
port=0

# Service binding host
bind=0.0.0.0

# Client idle timeout (in seconds)
client_timeout=600

# This service will be automatically registered to the specified external listener.
# Used to  forward user requests after a unified external listener.
# Example:  192.168.1.100:2000
remote_listener=

# Database opening mode
access_mode=READ_WRITE

# The maximum number of client that can connect to server at the same time
# The default is 256
max_connections=

# The maximum number of threads that the service layer can process at the same time
# The default is the number of CPU cores
max_workers=

# Maximum number of threads used on the DB side
# Default is 50% of the number of cores
# Best Practice: Aim for 5-10 GB memory per thread
threads=

# Maximum memory size used. Format:  ....(K|M|G)
# Default is 60% of available memory
# If memory resources are sufficient, you can also configure memory_limit to -1.
# -1 means all temporary files will exist only in the memory (only valid for memory mode)
memory_limit=

# Template file. When database is launched for the first time,
# a copy of this template file will be used.
template=

# Initialization script. Maybe file or directory.
# If it is a file, the file will be used.
# If it is a directory, all files with the .sql suffix in the directory will be used.
# The script(s in the directory) will be executed only when the in-memory database or file database is opened first time.
init_script=

# Startup script. Maybe file or directory.
# If it is a file, the file will be used.
# If it is a directory, all files with the .sql suffix in the directory will be used.
# The script(s in the directory) will be executed every time when database is opened.
startup_script=

# locale. The default language set of the program.
# If not set, it will be marked as the system default
locale=

# sql_history.  used to enable or disable the SQL history feature.
# Possible values:
# - ON: Enables SQL history tracking.
# - OFF: Disables SQL history tracking (default).
# When set to OFF (default), SQL execution history will not be recorded.
sql_history=OFF

# Specifies the minimum number of idle database connections that the connection pool maintains at any time.
# These connections are pre-established and kept available to handle incoming requests, helping to reduce latency during operations.
# Default Value: 3
connection_pool_minimum_idle=3

# Defines the maximum number of idle database connections that the connection pool can retain.
# Connections exceeding this limit will be closed to conserve system resources.
# Default Value: 10
connection_pool_maximum_idle=10

# Determines the maximum lifecycle time (in milliseconds) for a connection in the pool, regardless of whether it is active or idle.
# Once the lifecycle time is exceeded, the connection is closed and removed from the pool.
# Default Value: 900000 (15 minutes)
connection_pool_maximum_lifecycle_time=900000

```
### Proxy configuration file template
``` 
# PID file. Used to describe the process id of running server process.
# When server is running, the file will be exclusively locked.
# If this file is locked by other process, server will abort and not continue start.
# If not configured, this file will not be generated and the lock will not be checked.
pid=

# The location where the log file is saved
# CONSOLE means output to the console, and others mean output to a file
# Multiple logs can be output at the same time, separated by commas, for example, “console, logs/xx.log”
log=CONSOLE,logs/slackerdb-proxy.log

# Log level
log_level=INFO

# Service port
# 0 means the system will randomly assign a port
# -1 means no port will be opened
# default is 0, means random port.
port=0

# Service binding host
bind=0.0.0.0

# Client idle timeout (in seconds)
client_timeout=600

# The maximum number of threads that the service layer can process at the same time
# The default is the number of CPU cores
max_workers=

# locale. The default language set of the program.
# If not set, it will be marked as the system default
locale=

```

Note: All parameters are optional.   
You can keep only the parameters you need to modify.   
For parameters that are not configured, means default values will be used.

### Embed the db server in your code
``` 
  // create configuration,  and update as your need
  ServerConfiguration serverConfiguration = new ServerConfiguration();
  serverConfiguration1.setPort(4309);
  serverConfiguration1.setData("data1");
  
  // init database
  DBInstance dbInstance= new DBInstance(serverConfiguration1);
  
  // startup database
  dbInstance1.start();
  
  // shutdown database
  dbInstance.stop();
  
  // We currently supports starting multiple instances running at the same time.
  // But each instance must has his own port and instance name.

```

### Embed the db proxy in your code
``` 
    ServerConfiguration proxyConfiguration = new ServerConfiguration();
    proxyConfiguration.setPort(dbPort);
    ProxyInstance proxyInstance = new ProxyInstance(proxyConfiguration);
    proxyInstance.start();

// Waiting for server ready
    while (!proxyInstance.instanceState.equalsIgnoreCase("RUNNING")) {
        Sleeper.sleep(1000);
    }

```

### Jdbc program example with postgres client
``` 
    // "db1" is your database name in your configuration file.
    // 3175  is your database port in your configuration file.
    // If you are connecting for the first time, there will be no other users except the default main
    String  connectURL = "jdbc:postgresql://127.0.0.1:3175/db1";
    Connection pgConn = DriverManager.getConnection(connectURL, "main", "");
    pgConn.setAutoCommit(false);
   
    // .... Now you can execute your business logic.
```

### Jdbc program example with slackerdb client
``` 
    // "db1" is your database name in your configuration file.
    // 3175  is your database port in your configuration file.
    // If you are connecting for the first time, there will be no other users except the default main
    String  connectURL = "jdbc:slackerdb://127.0.0.1:3175/db1";
    Connection pgConn = DriverManager.getConnection(connectURL, "main", "");
    pgConn.setAutoCommit(false);
   
    // .... Now you can execute your business logic.
```

### Odbc and python program
``` 
    It also support ODBC and Python connection. 
```

## Use IDE tools to connect to the database
Since native Postgres clients often use some data dictionary information that duckdb doesn't have,   
We do not recommend that you use the PG client to connect to our database(That works, but has limited functionality).     
Instead, we suggest use the dedicated client provided in this project.

## Known Issues
### 1. User and password authorization
We do not support user password authentication, just for compatibility, keep these two options.  
you can fill in the password part as you like, it doesn't make sense.  
The user part will be used by the default schema of the user connection.

### 2. Limited support for duckdb datatype
Only some duckdb data types are supported, mainly simple types, such as int, number, double, varchar, ...
For complex types, some are still under development, and some are not supported by the PG protocol, such as blob, list, map...
You can refer to sanity01.java to see what we currently support.

### 3. postgresql-fdw
fdw will use "Declare CURSOR" to fetch remote data, while duck doesn't support this.

## Roadmap

...

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