KotgreSQL

A PostgreSQL client library written in pure Kotlin, made for use with Coroutines

Why you should use it

It's made for Kotlin and Coroutines

KotgreSQL's I/O is completely non-blocking (built with NIO) and suspend functions. You can do all interactions with the database from Coroutines without ever blocking the thread.

It's really easy to use

See the examples section below to get started

It's small and simple

Look ma, no Netty, no Reactor framework, no Spring Data! Just plain NIO, no dependencies apart from kotlin-coroutines. Only 127kB Jar File size (as of release 0.1).

It's 100% PostgreSQL

While portable database frameworks are a great thing for management presentations, in practical applications it is much better to focus on the strenghts and features of one particular product, so you can use all its features exactly as intended without additional layers of bloat in between.

If you ever need to switch to a different DB, this will probably be a big migration project anyway, regardless whether or not you use a (theoretically) portable Java framework.

This is why KotgreSQL is built and designed from the ground up for use with PostgreSQL only.

Features

Supports PostgreSQL 12, 13, 14 and 15
Ready for use with Amazon RDS for PostgreSQL
Authentication methods: cleartext password, md5 and SCRAM-SHA256
Simple queries and prepared statements

On the roadmap

Connection Pool (inspired by HikariCP)
Migration tool (inspired by Flyway)

Examples

Create a client

val postgresClient = PostgresClient(
  host = "localhost", 
  database = "mydb", 
  username = "me", 
  password = "XXX"
)

Simple query - map ResultSet to data class

 data class Bicycle(
     val id: Int,
     val name: String,
     val price: Int
 )

 postgresClient.withConnection { connection ->
     val bicycles = connection
         .executeQuery("select id,name,price from bicycles")
         .mapTo<Bicycle>()
 }

Prepared statement with placeholders

postgresClient.withConnection { connection ->
    connection.prepareStatement("""
        select id,name,price from bicycle 
        where name = $1 
        and price < $2
      """.trimIndent()
    ).use { stmt ->
        val bicycles = stmt.executeQuery("Topstone", 2000)
            .mapTo<Bicycle>()
    }
}

FAQ

What is KotgreSQL and why should I use it?

A Kotlin-native PostgreSQL client library made for use with Coroutines. You should use it when when you work with Coroutines and you want to avoid blocking the main thread, but you don't want to use a big bloated framework such as Spring Data / R2DBC

Can I use it with kotlin native?

No, it's made for the JVM platform only, as it relies heavily on NIO.

BastianVoigt/kotgresql