DB2/400: ArgumentException Column 'SQL_TYPE_NAME' does not belong to table DataTypes

[shessane]

Using NHibernate to access DB2 AS400 database. When upgrading to NHibernate 5.3.13 from 5.2.7, we face a regression in the FluentConfiguration.BuildSessionFactory() :

FluentNHibernate.Cfg.FluentConfigurationException : An invalid or incomplete configuration was used while creating a SessionFactory. Check PotentialReasons collection, and InnerException for more detail.

---- System.ArgumentException : Column 'SQL_TYPE_NAME' does not belong to table DataTypes.

Stack Trace: 
FluentConfiguration.BuildSessionFactory()

----- Inner Stack Trace -----
DB2MetaData.GetReservedWords()
SchemaMetadataUpdater.GetReservedWords(Dialect dialect, IConnectionHelper connectionHelper)
SchemaMetadataUpdater.UpdateDialectKeywords(Dialect dialect, IConnectionHelper connectionHelper)
SchemaMetadataUpdater.Update(ISessionFactoryImplementor sessionFactory)
SessionFactoryImpl.ctor(Configuration cfg, IMapping mapping, Settings settings, EventListeners listeners)
Configuration.BuildSessionFactory()
FluentConfiguration.BuildSessionFactory()

The problem seems the same as #fluent-nhibernate/504

Here's the line that create the problem :

nhibernate-core/src/NHibernate/Dialect/Schema/DB2MetaData.cs

Line 39 in 4dac4ca

result.Add(row["SQL_TYPE_NAME"].ToString());

In a debug session I can see that there's no colomn named "SQL_TYPE_NAME". I have instead a column named "TypeName".

The workaround consists of disabling IncludeDataTypesInReservedWords :

// ...
fluentConfiguration.Database(DB2400Configuration.Standard.ShowSql().ConnectionString(connectionString)
    .Dialect<CustomDB2As400Dialect>())
//...

public class CustomDB2As400Dialect : DB2400Dialect
{
    public override IDataBaseSchema GetDataBaseSchema(DbConnection connection)
    {
        return new CustomAs400MetaData(connection);
    }

    private class CustomAs400MetaData : DB2MetaData
    {
        public CustomAs400MetaData(DbConnection connection) : base(connection)
        {
        }

        public override bool IncludeDataTypesInReservedWords => false;
    }
}

I'll try to submit a fix that returns if the column "SQL_TYPE_NAME" is not found.

[hazzik]

I'm not entirely sure how this was working in 5.2.x for you, because, in 5.2.7 both DB2Dialect and DB2400Dialect were not implementing GetDataBaseSchema method, and dialect is (still) throwing a NotSupportedException:

nhibernate-core/src/NHibernate/Dialect/Dialect.cs

Lines 491 to 494 in 40779f9

	public virtual IDataBaseSchema GetDataBaseSchema(DbConnection connection)
	{
	throw new NotSupportedException();
	}

[hazzik]

Ok, found how, which is really bad:

nhibernate-core/src/NHibernate/Impl/SessionFactoryImpl.cs

Lines 213 to 228 in ac14311

	try
	{
	if (settings.IsKeywordsImportEnabled)
	{
	SchemaMetadataUpdater.Update(this);
	}
	if (settings.IsAutoQuoteEnabled)
	{
	SchemaMetadataUpdater.QuoteTableAndColumns(cfg, Dialect);
	}
	}
	catch (NotSupportedException ex)
	{
	// Ignore if the Dialect does not provide DataBaseSchema
	log.Warn(ex, "Dialect does not provide DataBaseSchema, but keywords import or auto quoting is enabled.");
	}

In short, you were using incorrect configuration in the first place. This is not a regression per se.

[bahusoid]

This is not a regression per se.

So now DB2400Dialect uses wrong metadata. Still looks like regression to me (as it's caused by #2058)

Your suggestion Restore previous behavior for DB2400Dialect, eg, throwing NotSupportedException; looks like the way to go.

[hazzik]

Sounds good

[fredericDelaporte]

This is fixed in 5.3.20 by #3451 (not yet released) by removing the metadata support for DB2/400. Feel free to recycle your current PR #3439 as a new feature, supporting the metadata for DB2/400. (Better wait for the fix to be merged back to master, which will have to wait for 5.3.20 then 5.4.x release, or merge it in your branch and work over it.)

[shessane]

I'll close this one and wait for master merge. Thanks

[fredericDelaporte]

That is now merged on master.