linq to sql batch delete

Question

I have the following DB: Posts which have an Id, Tags also with Id, and TagsToPosts table which have T

Answer 1

My solution which lets you make deletions determined by a class field:

public static void DeleteByPropertyList(List listToDelete, Expression> getField, DataContext context) where T : class {
    List> partitionedDeletes = listToDelete.Select(d => string.Format("'{0}'", getField.Compile()(d).ToString())).ToList().Partition(2000).ToList();
    Func>, string> GetFieldName = propertyLambda => ((MemberExpression)propertyLambda.Body).Member.Name;
    MetaTable metaTable = context.Mapping.GetTable(typeof(T));
    string tableName = string.Format("{0}.{1}", metaTable.Model.DatabaseName, metaTable.TableName);
    foreach (List partitionDelete in partitionedDeletes) {
        string statement = "delete from {0} where {1} in ({2})";
        statement = string.Format(statement, tableName, GetFieldName(getField), string.Join(",", partitionDelete));
        context.ExecuteCommand(statement);
    }
}

public static IEnumerable> Partition(this IList source, int size) {
    for (int i = 0; i < Math.Ceiling(source.Count / (double)size); i++)
    yield return new List(source.Skip(size * i).Take(size));
}

Usage:

    List deletions = new List();
    // populate deletions
    LinqToSqlHelper.DeleteByPropertyList(deletions, oi => oi.OrderItemId, context);

It only works with a single field, but it could be extended to composite fields easily enough.