GeorgSchneider / PostgresDoc

Unit of work + document database on Postgresql

PostgresDoc

PostgresDoc is a unit of work + document database on Postgresql. There are many reasons why Postgres makes a good document store including speed, stability, ecosystem, ACID transactions, mixing with relational data and joins.

As your program runs, record a series of data updates (the unit of work). At the end of the unit of work persist all the changes in a transaction. Changes can be inserts, updates or deletes. PostgresDoc also provides a querying API.

PostgresDoc is written in F# but provides APIs for F# (PostgresDoc) and C# (PostgresDocCs). The C# version simply translates to the F# API.

Unit of Work API

CSharp

public class Person 
{
    public Guid _id { get; set; }
    public string Name { get; set; }
    public int Age { get; set; }
    public string[] FavouriteThings { get; set; }
}

var ernesto = new Person
        {
            _id = Guid.NewGuid(),
            Name = "Ernesto",
            Age = 31,
            FavouriteThings = new[] { "Pistachio Ice Cream", "Postgresql", "F#" }
        };
var connString = "Server=127.0.0.1;Port=5432;User Id=******;Password=*****;Database=testo;";

var unitOfWork = new Queue<Operation<Guid>>();

// insert a document
unitOfWork.Enqueue(Operation.Insert(ernesto._id, ernesto));

// modify a document
ernesto.Age = 32;
unitOfWork.Enqueue(Do.Update(ernesto._id, ernesto));

// persist the changes in a transaction
UnitOfWork.Commit(connString, unitOfWork)

Querying

var ernesto = Query<Person>.For(
            connString, 
            "select data from Person where id = :id", 
            new Dictionary<string, object> { {"id", ernesto._id} });

FSharp

type Person = 
    { _id: System.Guid; age: int; name: string }

let store = { connString = "Server=127.0.0.1;Port=5432;User Id=*******;Password=*****;Database=testo;" }

let julio = { _id = System.Guid.NewGuid(); age = 30; name = "Julio" }
let timmy = { _id = System.Guid.NewGuid(); age = 3; name = "Timmy" }

// newer operations are prepended
let uow = [ 
    delete timmy._id timmy;
    update julio._id { julio with age = 31 };
    insert julio._id julio;
    insert timmy._id timmy;
    ]
commit store uow

Querying

let peopleWhoAreThirty = 
    [ "age", box (30) ] 
    |> query<Person> store "select data from people where data->>'age' = :age"

Expected Schema

The database table should have the same name as the type, an id column matching the type used for identifiers, and a json or jsonb data column. The table name should be lowercase.

In the example above I have used Guid (uuid) identifiers and a type called Person so:

create table "person" ( 
	id uuid NOT NULL PRIMARY KEY,
	data json NOT NULL 
);