Retain batch concept and return lines in groups of 1000

lib/zxystream.js

@@ -12,7 +12,7 @@ function ZXYStream(source, options) {
     options = options || {};
 
     this.source = source;
-    this._afterGet = this._afterGet.bind(this);
+    this.batch = options.batch || 1000;
 
     stream.Readable.call(this);
 }
@@ -38,14 +38,29 @@ ZXYStream.prototype._read = function() {
         return;
     }
 
-    stream.statement.get(stream._afterGet);
-};
+    var lines = '';
+    var error;
+    var remaining = stream.batch;
+    for (var i = 0; i < stream.batch; i++) stream.statement.get(afterGet);
 
-ZXYStream.prototype._afterGet = function(err, row) {
-    if (err && err.code === 'SQLITE_ERROR' && /no such table/.test(err.message)) return this.push(null);
-    if (err) return this.emit('error', err);
-    if (!row) return this.push(null);
-    this.push(toLine(row));
+    function afterGet(err, row) {
+        if (err && err.code === 'SQLITE_ERROR' && /no such table/.test(err.message)) {
+            // no-op
+        } else if (err) {
+            error = err;
+        } else if (!row) {
+            // no-op
+        } else {
+            lines += toLine(row);
+        }
+        if (!--remaining) {
+            if (error) {
+                stream.emit('error', error);
+            } else {
+                stream.push(lines || null);
+            }
+        }
+    }
 };
 
 function toLine(row) {