Remove columns from Azure Table Storage

问题

Here is a snippet of code I am using to read entities from Table storage:

public void OnReadingEntity(object sender, ReadingWritingEntityEventArgs args)
    {
        XNamespace AtomNamespace = "http://www.w3.org/2005/Atom";
        XNamespace AstoriaMetadataNamespace = "http://schemas.microsoft.com/ado/2007/08/dataservices/metadata";

        GenericEntity entity = args.Entity as GenericEntity;
        if (entity == null)
        {
            return;
        }

        // read each property, type and value in the payload   
        var properties = args.Entity.GetType().GetProperties();
        var q = from p in args.Data.Element(AtomNamespace + "content")
                                .Element(AstoriaMetadataNamespace + "properties")
                                .Elements()
                where properties.All(pp => pp.Name != p.Name.LocalName)
                select new
                {
                    Name = UnescapePropertyName(p.Name.LocalName),
                    IsNull = string.Equals("true", p.Attribute(AstoriaMetadataNamespace + "null") == null 
                        ? null 
                        : p.Attribute(AstoriaMetadataNamespace + "null").Value, StringComparison.OrdinalIgnoreCase),
                    TypeName = p.Attribute(AstoriaMetadataNamespace + "type") == null 
                        ? null 
                        : p.Attribute(AstoriaMetadataNamespace + "type").Value,
                    p.Value
                };

        foreach (var dp in q)
        {
            entity[dp.Name] = GetTypedEdmValue(dp.TypeName, dp.Value, dp.IsNull);
        }
    }

Unfortunately this piece of code will return some properties that existed in entities I've deleted.

Can someone explain why is that?

回答1:

Azure table storage doesnt have columns as you're used to in relational databases. Each row can have completely different properties other than the mandatory columns.

When you say "still shows Up" I'm assuming this is just the way the tool you are using is presenting the data that is making you think its like a relational table.

See http://msdn.microsoft.com/en-us/magazine/ff796231.aspx for some good technical background.

来源：https://stackoverflow.com/questions/10750026/remove-columns-from-azure-table-storage