Heap Order Countersignature with airSlate SignNow

Heap save countersignature

Hey guys, I am Venkat and in this video, we'll  discuss what is a heap table? How to create and   when to use it? Along the way, we'll understand  the concept of table scan as well. We'll also look   at a simple example in action where a full table  scan is much better from performance standpoint   than using a table index. Finally, we'll also  discuss, how to force the database query engine   to use a specific index to find the data we  are looking for. Now, understanding all these   concepts is very important when you're tuning sql  queries for better performance. There's a quite a   bit of ground to cover, so let's get started.  Consider this Employees table. EmployeeId   is the primary key, so by default, a clustered  index on this column is created. This means,   the data rows that are physically stored in this  Employees table are sorted by EmployeeId column.   Now, before we understand what is a heap table,  let's first understand, what happens if we don't   have a clustered index on a table? Well, it is  the clustered index that determines the order   in which data rows are physically stored in a  table. Without a clustered index, the data rows   are not guaranteed to be in any specific order in  the table. This kind of a table is called a heap.   It may have one or more non-clustered indexes  but if it doesn't have a clustered index then   such a table is called a heap table or just heap.  So, in short, a table without a clustered index   is called heap. Now, what do you think is going  to happen when we select data from a heap? Will   the database engine use index seek, index scan or  table scan? Well, it depends really, we already   know, a heap is a table without a clustered index  but it may have one or more non-clustered indexes,   but for this example, let's assume, the heap  does not have any non-clustered indexes as well.   If there are no non-clustered indexes on the heap,  the search query uses table scan to find the data   that we are looking for. What is a table scan?  Well, as the name implies, a table scan scans   every row in the table to find the data that we  are looking for. Let's look at this in action.   We have a very simple sql script here. The first  part of the script creates the Gender table with   two columns - GenderId and GenderName, and the  second part of the script inserts three rows   into the Gender table. So, let's quickly execute  the script. Now, here's the important bit to keep   in mind, notice the create table script, we  did not mark any of the columns as a primary   key and we also did not create a clustered index  on this table explicitly. So, the physical order   in which data rows are stored in this table is not  guaranteed. In a nutshell, this Gender table is a   heap....