Using Apache Ignite from a Scala Agent

The Scala SDK already wraps golem:rdbms/ignite2@1.5.0 in golem.host.Rdbms.

Imports


import golem.host.Rdbms
import golem.host.Rdbms._

Open a Connection

Ignite uses thin-client URLs like ignite://host:10800.


Rdbms.Ignite.open("ignite://127.0.0.1:10800")

open, query, execute, commit, and rollback all return Either[DbError, T] instead of throwing.

If the user asks for a method that returns a plain String, keep the public method signature as String and handle host errors inside the method (e.g. with .fold(e => throw new RuntimeException(e.toString), identity)) rather than changing the signature to Either[DbError, _].

Query Data

Ignite placeholders use ?.


val message =
  for {
    conn   <- Rdbms.Ignite.open("ignite://127.0.0.1:10800")
    result <- conn.query("SELECT ?", List(IgniteDbValue.DbString("hello")))
    row    <- result.rows.headOption.toRight(DbError.Other("query returned no rows"))
    value  <- row.values.headOption.toRight(DbError.Other("query returned no columns"))
    text   <- value match {
                case IgniteDbValue.DbString(value) => Right(value)
                case other                         => Left(DbError.Other(s"Unexpected Ignite value: $other"))
              }
  } yield text

Execute Statements


conn.execute(
  """CREATE TABLE IF NOT EXISTS notes (
    |    id INT PRIMARY KEY,
    |    body VARCHAR
    |) WITH "CACHE_NAME=notes"""".stripMargin,
  List.empty,
)

When creating Ignite tables through SQL, include WITH "CACHE_NAME=...".

Transactions


for {
  conn <- Rdbms.Ignite.open(url)
  tx   <- conn.beginTransaction()
  _    <- tx.execute(
            "INSERT INTO notes (id, body) VALUES (?, ?)",
            List(IgniteDbValue.DbInt(1), IgniteDbValue.DbString("hello")),
          )
  _    <- tx.commit()
} yield ()

If you need transactional tables, create them with ATOMICITY=TRANSACTIONAL in the table options.