Ecto ClickHouse Adapter

Uses Ch as driver.

Installation

defp deps do
  [
    {:chto, github: "plausible/chto"}
  ]
end

Usage

In your config/config.exs

config :my_app, ecto_repos: [MyApp.Repo]
config :my_app, MyApp.Repo, url: "http://username:password@localhost:8123/database"

In your application code

defmodule MyApp.Repo do
  use Ecto.Repo,
    otp_app: :my_app,
    adapter: Ecto.Adapters.ClickHouse
end

Caveats

Ecto schemas

For automatic RowBinary encoding some schema fields need to use custom types:

defmodule MyApp.Example do
  use Ecto.Schema

  @primary_key false
  schema "example" do
    field :numeric_types_need_size, Ch.Types.UInt32
    field :no_custom_type_for_strings, :string
    field :datetime, :naive_datetime
    field :maybe_name, Ch.Types.Nullable, type: :string
    field :country_code, Ch.Types.FixedString, size: 2
    field :price, Ch.Types.Decimal32, scale: 2
  end
end

MyApp.Repo.insert_all(MyApp.Example, rows)

Schemaless inserts

For schemaless inserts :types is required

types = [
  numeric_types_need_size: :u32,
  no_custom_type_for_strings: :string,
  datetime: :datetime,
  maybe_name: {:nullable, :string},
  country_code: {:string, _size = 2},
  price: {:decimal, _size = 32, _scale = 2}
]

MyApp.Repo.insert_all("example", rows, types: types)

Settings

:settings option can be used to enable asynchronous inserts, lightweght deletes, and more

MyApp.Repo.insert_all(MyApp.Example, rows, settings: [async_insert: 1])
MyApp.Repo.delete_all("example", settings: [allow_experimental_lightweight_delete: 1])

ARRAY JOIN

:inner_lateral and :left_lateral join types are used for ARRAY JOIN and LEFT ARRAY JOIN until Ecto adds :array_join types.

ARRAY JOIN example:

"arrays_test"
|> join(:inner_lateral, [a], r in "arr", on: true)
|> select([a, r], {a.s, r.arr})

SELECT a0."s", a1."arr"
FROM "arrays_test" AS a0
ARRAY JOIN "arr" AS a1

NULL

DEFAULT expressions on columns are ignored when inserting RowBinary.

See Ch for more details and an example.

UTF-8

Both :binary and :string Ecto types are decoded as UTF-8 since Ecto doesn't call adapter's loaders for base types.

See Ch for more details and an example.

Benchmarks

See Ch for benchmarks.