## Cursors and streaming

By default prepared query execution fetches all rows, you can use a `Cursor` to control the amount of rows you want to read:

    connection.prepare("SELECT * FROM users WHERE age > ?", { ar1 ->
      if (ar1.succeeded()) {
        def pq = ar1.result()

        // Create a cursor
        def cursor = pq.cursor(Tuple.of(18))

        // Read 50 rows
        cursor.read(50, { ar2 ->
          if (ar2.succeeded()) {
            def rows = ar2.result()

            // Check for more ?
            if (cursor.hasMore()) {
              // Repeat the process...
            } else {
              // No more rows - close the cursor
              cursor.close()
            }
          }
        })
      }
    })

Cursors shall be closed when they are released prematurely:

    cursor.read(50, { ar2 ->
      if (ar2.succeeded()) {
        // Close the cursor
        cursor.close()
      }
    })

A stream API is also available for cursors, which can be more convenient, specially with the Rxified version.

    connection.prepare("SELECT * FROM users WHERE age > ?", { ar1 ->
      if (ar1.succeeded()) {
        def pq = ar1.result()

        // Fetch 50 rows at a time
        def stream = pq.createStream(50, Tuple.of(18))

        // Use the stream
        stream.exceptionHandler({ err ->
          println("Error: ${err.getMessage()}")
        })
        stream.endHandler({ v ->
          println("End of stream")
        })
        stream.handler({ row ->
          println("User: ${row.getString("last_name")}")
        })
      }
    })

The stream read the rows by batch of `50` and stream them, when the rows have been passed to the handler, a new batch of `50` is read and so on.

The stream can be resumed or paused, the loaded rows will remain in memory until they are delivered and the cursor will stop iterating.