Aggregate - On how many attributes can i use a group by


I have 2 entities that I want to join.

The master entity has 20 attributes (Id included) and I need 19 in my reslult. From the detail entity I need the sum of one attribute.

To do this I started to group by the attributes on my master entity. The first 17 attributes worked, but when I add an 18 attribute I get an InvalidZip exception (stacktrace at the bottom). I removed the last group by and the exception dissapears. So I thougth there was a problem with teh attribute. I added the 19th attribute, same exception. Removed this group by, exception dissapears again. Then I tought 2 bad attributes, but they are of a differents type (boolean and decimal).

Then I added one of the 2 again to get the exception. After receiving the exception I removed an other group by and the exception dissapears again. 

The sum of the detail entity could be added without a problem.

My conclusion was, on 1 entity I can't do more then 17 group by's. 

Is my cnclusion correct or am I doeing something wrong?

Kind regards



[1] InvalidZip
at OutSystems.Model.Implementation.Oml.Oml.omi#????????(Stream ?, Stream ?)
at OutSystems.Model.Implementation.Oml.Oml.GetOmlHeader(Stream inputStream)
at OutSystems.Server.Infrastructure.ModelOperations.OmlLoader.LoadOml(Stream oml, Stream partialOml, String productKey, Boolean skipUpgrade)
at OutSystems.Server.Infrastructure.ModelOperations.OmlLoaderExtensions.LoadOml(IOmlLoader omlLoader, Byte[] oml, Byte[] partialOml, String productKey, Boolean skipUpgrade)
at cs#lqcwjvun.cs#fubnaotv(CompilationContext dil, Byte[] dim, Byte[] din, Boolean dio)
at cs#lqcwjvun.cs#ivrkpgtd.cs#ttvufkxt()
at cs#lqcwjvun.cs#fubnaotz(CompilationContext djc, Action djd)
at cs#lqcwjvun.cs#fubnaotq(IMessageBroker dgz, CompilerContextServices dha, ResourcesInManifestCacheRepository dhb, Byte[] dhc, String dhd, Int32 dhe, String dhf, Int32 dhg, Application dhh, IDictionary`2 dhi, String& dhj, String& dhk, String& dhl, String& dhm)
at OutSystems.HubEdition.DeploymentController.Compiler.TestQuery(ICompilerContext ctx, Guid operationId, Byte[] oml, Int32 espaceId, String espaceName, Int32 tenantId, String queryCompoundKey, Int32 maxRecords)

[2] Unexpected EOF
at ICSharpCode.SharpZipLib.Zip.Compression.Streams.InflaterInputStream.Fill()
at ICSharpCode.SharpZipLib.Zip.Compression.Streams.InflaterInputStream.Read(Byte[] buffer, Int32 offset, Int32 count)
at OutSystems.RuntimeCommon.StreamUtils.PumpStream(Stream inputStream, Stream outputStream, Int32 bufferSize)
at OutSystems.Model.Implementation.Oml.Oml.omi#????????(Stream ?, Stream ?)

hi Kevin,

can you present us the entity with its attributes and datatypes including the query?



Hi Kevin,

This seems like a Platform bug, make sure to send it to OutSystems Support as well.

@Kilian Hekhuis and @Hans 

I was building a demo application and I didn't receive the error until I inserted data.

Oml file in attachment


Hi Kevin,

I tried opening the demo application and I didn't get any error while inserting the data :

It seems like there is a bug with your platform? Can you test it on your personal environment and see if it works there?

@Nick Vandebriel 

The error is in the studio, not on the webpage.

Hi Kevin Desmet.

I faced that issue as well, when we have a lot of fields grouped, the aggregate does not give a preview of the data (don't know why... seems some kind of limitation), but in run-time should work properly.


Gonçalo Almeida

hi @Goncalo Almeida 

I know that at runtime everything works fine, but I don't want to have errors in my studio to avoid confusion.


Hi Kevin,

Please use the feedback button in Service Studio to report this, if you haven't already, thanks!

I have already reported this to outsystems


I've talked to OutSystems, and it seems a limitation in some library they are using to retrieve the results. But it's good you reported it, maybe they'll get on with fixing it :).

Problem's still here. Rather annoying I must say.

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