Can GZip compression (via .net) increase file size?

问题

I keep track of the original size of the files that I'm compressing using .Net's GZipStream class, and it seems like the file that I thought I was compressing has increased in size. Is that possible?

This is how I'm doing the compression:

Byte[] bytes = GetFileBytes(file);

using (FileStream fileStream = new FileStream("Zipped.gz", FileMode.Create))
{
    using (GZipStream zipStream = new GZipStream(fileStream, CompressionMode.Compress))
    {
        zipStream.Write(bytes, 0, bytes.Length);
    }
}

回答1:

Yes, it can. It has been fixed in .NET 4.

The compression algorithms for the System.IO.Compression..::.DeflateStream and System.IO.Compression..::.GZipStream classes have improved so that data that is already compressed is no longer inflated. This results in much better compression ratios. Also, the 4-gigabyte size restriction for compressing streams has been removed.

Check: GZipStream/DeflateStream increase file size on compression

Also check here SO: GZipStream and DeflateStream produce bigger files

回答2:

Another reason could be that you include .git folder when you compress, which inflates as you develop and use git.

For me, excluding .git solved the problem.

来源：https://stackoverflow.com/questions/3973485/can-gzip-compression-via-net-increase-file-size