Node + SQL Server : Get row data as stream - sql-server

Question

I try to use Node.Js connector with Microsoft driver to communicate with a SQL Server. In the connector docs I've found a good option named 'stream'. It add ability to asynchronously obtain row objects.
My data have some specific - some columns have large binary data (> 100 Mb). So even one row may be really large. I'm looking for ability to get each row data as a stream. It is possible in .NET driver (CommandBehavior.SequentialAccess enumeration). Is it possible in Node.js?
UPDATED
Here is a code to demonstrate the problem:
Custom writable stream module:
var stream = require('stream');
var util = require('util');
function WritableObjects() {
stream.Writable.call(
this,
{
objectMode: true
}
);
}
util.inherits( WritableObjects, stream.Writable );
WritableObjects.prototype._write = function( chunk, encoding, doneWriting ) {
console.log('write', chunk, encoding);
doneWriting();
};
module.exports = {
WritableObjects: WritableObjects
};
and database query code:
var sw = new wstream.WritableObjects();
var request = new sql.Request(connection);
request.stream = true;
request.pipe(sw);
request.query('SELECT DataId, Data FROM ds.tData WHERE DataId in (1)');
sw.on('error', function(err) {
console.log('Stream err ', err)
});
sw.on('pipe', function(src) {
console.log('Stream pipe ')
});
sw.on('finish', function(data) {
console.log('Stream finish')
});
I this example chunk parameter of _write method contains the whole data of db record, not a stream. Because Data field contains a big varbinary data memory of node process also grows huge.

Answer 1

Yes you can stream query with the node-mssql package as stated here: https://github.com/patriksimek/node-mssql
stream - Stream recordsets/rows instead of returning them all at once as an argument of callback (default: false). You can also enable streaming for each request independently (request.stream = true). Always set to true if you plan to work with large amount of rows.