Common Examples of SSIS Expressions and Variables

Introduction

This article helps to enrich the functionality of SSIS. It is possible for example to set properties in tasks using expressions and we can assign values and create code to enrich the SSIS functionality.

This article is oriented to SSIS developers who have experience with basic tasks, but are not familiar with variables, scripts to enrich the functionality of the SSIS and to provide dynamic functionality.

This time we will talk about SSIS expressions, variables, and loops in SSIS. We will use expressions to set values in tasks using variables. We will also learn to create Script code in C#.

We will first talk about SSIS expressions and then we will use SSIS with the script task. Finally, we will work with Loop containers and the script task.

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Comparing Objects by Value. Part 2. Implementation Notes of the Equals Method

In the previous article, we have reviewed a general concept of implementing a minimum set of required modifications that include overriding the Object.Equals(Object) and Object.GetHashCode() methods in order to compare class objects by value on a standard .NET framework.

Let’s consider the implementation features of the Object.Equals(Object) method so that it meets the following documentation requirement:

x.Equals(y) returns the same value as y.Equals(x).

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Everything you should know about SQL Server JOINS

The focus of this article is going to be on utilizing JOINs. We will start off by talking a bit about how JOINs are going to happen and why you need to JOIN data. Then we will take a look at the JOIN types that we have available to us and how to use them.

JOIN BASICS

JOINs in TSQL are typically going to be done on the FROM line.

JOIN-Starts-Here

Before we are getting to anything else, the real big question becomes — “Why do we have to do JOINs, and how are we actually going to perform our JOINs?” (more…)

Comparing Objects by Value. Part 1. Beginning

It is a common fact that the .NET object model, as well as other software program platforms, allow comparing objects by reference and by value.

By default, two objects are equal if the corresponding object variables have the same reference. Otherwise, they are different.

However, in some cases, you may need to state that two objects belonging to the same class are equal if their content match in a certain way.

Assume we have the Person class, which contains some personal data – First Name, Last Name, and Birth date.

Consider the following points:

  1. What is the minimum required number of class modifications to assure comparing class objects by values with the help of the standard .NET architecture?
  2. What is the minimum required number of class modifications to assure comparing class objects by values (every time, if not explicitly stated that objects may be compared by a reference) with the help of the standard .NET architecture?

For each case, we will see the best way to compare objects by value to get a consistent, compact, copy-paste free, and productive code. It is not as trivial as it may seem for the first time.

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Extended Events for SSAS

Cubes require frequent monitoring since their productivity decreases quite often (slowdowns during query building, processing time increment). To find out the reason of decrease, we need to monitor our system. For this, we use SQL Server Profiler. However, Microsoft is planning to exclude this SQL tracing tool in subsequent versions. The main disadvantage of the tool is resource intensity, and it should be run on a production server carefully, since it may cause a critical system productivity loss.

Thus, Extended Events is a general event-handling system for server systems. This system supports the correlation of data from SQL Server which allows getting SQL Server state events. (more…)

Composition and Interfaces in OOP World

In the object-oriented programming world, the concept of inheritance has been criticized for a long time.

There are quite a lot of arguments:

  • A derived class inherits all the parent’s data and behavior that is not always necessary. When modifying a parent class, some data and behavior that are not supposed to be in the derived class get into it;
  • Virtual methods are less productive. If a language allows declaring a non-virtual method, what would you do when you need to override one in an inherited method? You can mark the method with the new keyword, however, in this case, polymorphism will not work. The consequent use of this object may cause unexpected behavior, depending on the type the object is going to be converted to.
  • The vast majority of languages do not allow multiple inheritance.
  • There are tasks where inheritance is helpless. Consider the case, when you need to create a container (array, list, or set) and implement the same behavior for elements with different types. In addition, you need to provide static typing. In this case, generics will come to help.

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Sorting in .NET

Sorting is a typical task each programmer should be aware of. That’s why this article is dedicated to the implementation of sorting in .NET. I will describe how array sorting works in .NET, its aspects, and make a small comparison with sorting in Java.

Let’s begin with the fact that the first versions of .NET use the quicksort algorithm by default. So, let’s consider pros and cons of the quicksort.

Pros

  1. One of the most high-performance algorithms(on a practical level) of general-purpose internal sorting.
  2. Easy implementation.
  3. Requires just O(logn) of additional memory for its operation.
  4. Can be easily combined with caching and internal memory mechanisms.

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Aspects of Strings in .NET

The string data type is one of the most significant data types in any programming language. You can hardly write a useful program without it. Nevertheless, many developers do not know certain aspects of this type. Therefore, let’s consider these aspects.

Representation of strings in memory

In .Net, strings are located according to the BSTR (Basic string or binary string) rule. This method of string data representation is used in COM (the word ‘basic’ originates from the Visual Basic programming language in which it was initially used). As we know, PWSZ (Pointer to Wide-character String, Zero-terminated) is used in C/C++ for representation of strings. With such location in memory, a null-terminated is located in the end of a string. This terminator allows to determine the end of the string. The string length in PWSZ is limited only by a volume of free space. (more…)

StringBuilder: the Past and the Future

In the previous article, I elaborated on peculiarities of string concatenation. In this article, I would like to consider the StringBuilder class in detail.

As we all know, strings in .Net are immutable (without use of unsafe). Therefore, it is not a good idea to perform concatenation frequently. It means that the following code has quite serious problems with memory load:

So, what is wrong with this code?
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The origin of GetHashCode in .NET

This article is devoted to the GetHashCode method and the GetHashCode implementation in the .NET Framework. The article also discusses the different behavior of the method for reference types and value types. The topic is quite interesting and any self-respecting .NET developer needs to know it. So let’s go!

What’s stored in reference-type objects apart from their field?

Let’s begin our story with learning what is stored in reference-type objects in addition to their fields.

Each reference type object has the so-called header, which consists of two fields: a pointer to the type of the object (MethodTablePointer), as well as a synchronization index (SyncBlockIndex).

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