Re: [Mssqlcompressed-users] GZIP Compression level

[Robert E. <re...@co...>]

Just a follow up for anyone interested:

I've been digging through the code for the gzip compressor and it turns out
the compression level on the gzip is never set so its always defaulting to
9:

In GzipTransform.cs:

return new GZIPOutputStream(writeToStream, level);

should be something like this:

var compressedOutputStream = new GZipOutputStream(writeToStream);
compressedOutputStream.SetLevel(level);
return compressedOutputStream;

I imagine the same is true of the bzip2 plugin etc.

Once that's done and built etc it works like a charm!

On 8 January 2013 10:29, Robert Emery <re...@co...> wrote:

> Hi,
>
> We are testing msbp with gzip compression against a test db (3.5GB) on
> SQL Server 2005 SP4, Server 2008 Standard using the following commands
>
> msbp.exe backup "db(database=VehicleData)" "gzip(level=1)"
> "local(path=F:\SQLDumps\VehicleData\VehicleData_backup_20130104_l1.bak.gz)"
> msbp.exe backup "db(database=VehicleData)" "gzip(level=9)"
> "local(path=F:\SQLDumps\VehicleData\VehicleData_backup_20130104_l9.bak.gz)"
>
> We've found that changing the gzip level makes no difference as to the
> size or amount of time taken to perform the backup?
> uncompressed: 3530221KB, approx 55 seconds
>
> level=1 400,515KB Approx 4 mins
> level=9 400,514KB Approx 4 mins
>
> For us, we are looking to get *some* compression (even 8:10 would be
> enough) without a large decrease in speed.
>
> Two questions: does the gzip level definitely get applied and is there
> a way for me to verify this?
> Secondly: does anyone have any recommendations how to decrease the
> duration for gzip level=1?
>
> Something I also noticed, when I gunzipped the files and then re-gzipped
> them
> with the gzip command on our linux server, the file sizes came out larger
> for
> level=1.
>
> Many Thanks,
>
> --
> Robert Emery
> Database Administrator
>