testparquet.cs

using System;
using System.Collections.Generic;
using ParquetSharp;
void Main()
{
	SaveToParquet();
}
public static void SaveToParquet()
{
	var objectIds = new Entity[3];
	objectIds[0] = new Entity { Id = 1, ElementId = 1 };
	objectIds[1] = new Entity { Id = 2, ElementId = 2 };
	objectIds[2] = new Entity { Id = 3, ElementId = 3 };

	var columns = new ParquetSharp.Column[]
	{
			new Column<int>("Id"),
			new Column<int>("ElementId"),
	};
	string  path = @"C:\Users\vho2\OneDrive - Exyte\Documents\LINQPad Queries\float_timeseries.parquet";
	using var file = new ParquetFileWriter(path, columns);
	using var rowGroup = file.AppendRowGroup();

	using (var timestampWriter = rowGroup.NextColumn().LogicalWriter<int>())
	{
		timestampWriter.WriteBatch(objectIds.Select(x => x.Id).ToArray());
	}
	using (var timestampWriter = rowGroup.NextColumn().LogicalWriter<int>())
	{
		timestampWriter.WriteBatch(objectIds.Select(x => x.ElementId).ToArray());
	}
	file.Close();
	Console.WriteLine("Done");
}
public class Entity
{
	public int Id { get; set; }
	public int ElementId { get; set; }
}
// You can define other methods, fields, classes and namespaces here