Slick 3.0 bulk insert or update (upsert)

There are several ways that you can make this code faster (each one should be faster than the preceding ones, but it gets progressively less idiomatic-slick):

• Run insertOrUpdateAll instead of insertOrUpdate if on slick-pg 0.16.1+

  await(run(TableQuery[FooTable].insertOrUpdateAll rows)).sum
  

• Run your DBIO events all at once, rather than waiting for each one to commit before you run the next:

  val toBeInserted = rows.map { row => TableQuery[FooTable].insertOrUpdate(row) }
  val inOneGo = DBIO.sequence(toBeInserted)
  val dbioFuture = run(inOneGo)
  // Optionally, you can add a `.transactionally`
  // and / or `.withPinnedSession` here to pin all of these upserts
  // to the same transaction / connection
  // which *may* get you a little more speed:
  // val dbioFuture = run(inOneGo.transactionally)
  val rowsInserted = await(dbioFuture).sum
  

• Drop down to the JDBC level and run your upsert all in one go (idea via this answer):

  val SQL = """INSERT INTO table (a,b,c) VALUES (?, ?, ?)
  ON DUPLICATE KEY UPDATE c=VALUES(a)+VALUES(b);"""
  
  SimpleDBIO[List[Int]] { session =>
    val statement = session.connection.prepareStatement(SQL)
    rows.map { row =>
      statement.setInt(1, row.a)
      statement.setInt(2, row.b)
      statement.setInt(3, row.c)
      statement.addBatch()
    }
    statement.executeBatch()
  }