Memory issues on knex.js when using streams - node.js

Question

I'm trying to export a whole sqlite3 database table to CSV using knex.js. As the table can up to 300000 rows, i use streams to don't have memory issues. But if i look the memory usage of my app it up to 800MB or i have an "out of memory" error.
How can i handle a large query result with knex.js on sqlite3 database?
Below a sample of code :
knex.select().from(table).stream(function (stream) {
var stringifier = stringify(opts);
var fileStream = fs.createWriteStream(file);
var i = 0;
stringifier.on('readable', function() {
var row;
while (row = stringifier.read()) {
fileStream.write(row);
console.log("row " + i++); //debug
}
});
fileStream.once('open', function(fd) {
stream.pipe(stringifier);
});
});
EDIT
Seems knex.js streams for sqlite3 database are "fake" streams.
Below the source code of the stream function for sqlite3 in knex :
Runner_SQLite3.prototype._stream = Promise.method(function(sql, stream, options) {
/*jshint unused: false*/
var runner = this;
return new Promise(function(resolver, rejecter) {
stream.on('error', rejecter);
stream.on('end', resolver);
return runner.query(sql).map(function(row) {
stream.write(row);
}).catch(function(err) {
stream.emit('error', err);
}).then(function() {
stream.end();
});
});
});
We see that it waits for the request to be executed before create the stream
from the result array.
VERSION:
Knex.Js 0.7.5
node 0.12
Thx for your help.

Answer 1

I think there are no solutions. I use limit and offset to get all data step by step with knex.js and i write each row in a write stream.
An implementation example for those who wants :
exportTable: function(table, writeStream) {
var totalRows;
var rowLimit = _config.ROW_LIMIT;
return DatabaseManager.countAll(table).then(function(count) {
totalRows = count[0]['count(*)'];
var iterations = new Array(Math.ceil(totalRows / rowLimit));
return Promise.reduce(iterations, function(total, item, index) {
return _knex.select().from(table).limit(rowLimit).offset(index * rowLimit).map(function(row) {
writeStream.write(row);
}).catch(function(err) {
return Promise.reject(err);
});
}, 0).then(function() {
return Promise.resolve();
}).catch(function(err) {
return Promise.reject(err);
});
}).catch(function(err) {
console.log(err);
return Promise.reject(err);
});
}