Streaming Results

This comparison shows the difference between callback-based and Promise-based result streaming.

Without this library: Use callbacks for query execution, leading to nested callback coordination and unpredictable execution order.

With this library: Use async/await for query execution, enabling clean sequential code flow. This example also demonstrates modern for await streaming instead of traditional event handlers.

Examples

tip

Click "WITHOUT Helper Library" to see the original code
Click "WITH Helper Library" to see the improved code using this library

WITHOUT Helper Library
WITH Helper Library

Based on an example from the Snowflake SDK documentation.

// Not using the Promise Helper Library

connection.execute({
  sqlText:
    "SELECT L_COMMENT FROM SNOWFLAKE_SAMPLE_DATA.TPCH_SF100.LINEITEM LIMIT 100000",
  streamResult: true,
  complete: function (err, stmt) {
    if (err) {
      console.error("Query failed:", err);
      return;
    }

    const stream = stmt.streamRows();
    // Complex event-based streaming
    stream
      .on("readable", function (row) {
        while ((row = this.read()) !== null) {
          console.log(row);
        }
      })
      .on("end", function () {
        console.log("done");
      })
      .on("error", function (err) {
        console.error("Stream error:", err);
      });
  },
});

// This executes immediately, before streaming completes!
console.log("This will likely execute before completion due to async behavior!");

// Using the Promise Helper Library

const { statement } = connection.execute({
  sqlText:
    "SELECT L_COMMENT FROM SNOWFLAKE_SAMPLE_DATA.TPCH_SF100.LINEITEM LIMIT 100000",
  streamResult: true,
});

try {
  const stream = statement.streamRows();
  // Using modern `for await` iteration
  for await (const row of stream) {
    console.log(row);
  }
  console.log("done");
} catch (error) {
  console.error("Stream error:", error);
}

// This executes after streaming completes - predictable order!
console.log("This will execute after streaming completes.");

Examples​

Examples