# Pillar
Clickhouse elixir driver via HTTP connection
# Features
- [Direct Usage with connection structure](#direct-usage-with-connection-structure)
- [Pool of workers](#pool-of-workers)
- [Async insert](#async-insert)
- [Buffer for periodical bulk inserts](#buffer-for-periodical-bulk-inserts)
- [Migrations](#migrations)
## Usage
### Direct Usage with connection structure
```elixir
conn = Pillar.Connection.new("http://user:password@localhost:8123/database")
# params are passed in brackets {} in sql query, and map strtucture does fill query by values
sql = "SELECT count(*) FROM users WHERE lastname = {lastname}"
params = %{lastname: "Smith"}
{:ok, result} = Pillar.query(conn, sql, params)
result
#=> [%{"count(*)" => 347}]
```
### Pool of workers
Recommended usage, because of limited connections and supervised workers
```elixir
defmodule ClickhouseMaster do
use Pillar,
connection_strings: [
"http://user:password@host-master-1:8123/database",
"http://user:password@host-master-2:8123/database"
],
name: __MODULE__,
pool_size: 15
end
ClickhouseMaster.start_link()
{:ok, result} = ClickhouseMaster.select(sql, %{param: value})
```
### Async insert
```elixir
connection = Pillar.Connection.new("http://user:password@host-master-1:8123/database")
Pillar.async_insert(connection, "INSERT INTO events (user_id, event) SELECT {user_id}, {event}", %{
user_id: user.id,
event: "password_changed"
}) # => :ok
```
### Buffer for periodical bulk inserts
For this feature required [Pool of workers](#pool-of-workers)
```elixir
defmodule BulkToLogs do
use Pillar.BulkInsertBuffer,
pool: ClickhouseMaster,
table_name: "logs",
interval_between_inserts_in_seconds: 5
end
```
```elixir
:ok = BulkToLogs.insert(%{value: "online", count: 133, datetime: DateTime.utc_now()})
:ok = BulkToLogs.insert(%{value: "online", count: 134, datetime: DateTime.utc_now()})
:ok = BulkToLogs.insert(%{value: "online", count: 132, datetime: DateTime.utc_now()})
....
# all this records will be inserted with 5 second interval
```
### Migrations
Migrations can be generated with mix task `mix pillar.gen.migration migration_name`
```bash
mix pillar.gen.migration events_table
```
But for launching them we have to write own task, like this:
```elixir
defmodule Mix.Tasks.MigrateClickhouse do
use Mix.Task
def run(_args) do
connection_string = Application.get_env(:my_project, :clickhouse_url)
conn = Pillar.Connection.new(connection_string)
Pillar.Migrations.migrate(conn)
end
end
```
And launch this via command
```bash
mix migrate_clickhouse
```
# Contribution
Feel free to make a pull request. All contributions are appreciated!
