 Hi there, this is Krishnan from Bitescout and in this video, we will be going to learn about one of the tsql execution plan operator called indexCant which you have might seen in the execution plan. As a developer, many times we are in a situation where some of our query is not performing well. So as a part of troubleshooting process, you will want to look at the execution plan and see if there are any indication as to why the problem is occurring. Well, basically an execution plan is a tree of operators. SQL Server 2014 has more than 100 different operators. So in execution plan, when you see indexCant operator, it indicates that a SQL server has to scan the data or index pages to find the appropriate records. And the second operator in the scan is a clustered indexCant and it is similar to the table scan and it indicates a retrieval of all rows from a table with a clustered index. Now let's perform the demo for this operator. Alright, so let's get started with indexCant for this table. For the demo, I have created a new table called patientMaster and here you can see that I have not defined the primary key for this column. And that means a table without primary key is called a heap. Now let us close this. Now before executing this query, let me enable the execution plan. And now let's execute this query. So here I get nine rows and if I look at the execution plan, we can see that we have a table scan here on patientMaster. And by looking at the table scan tooltip, we can see that we don't have a clustered index on that table. So that would be a noteworthy item to pay an attention to. Now let's create the unique clustered index on patientId column by executing this script. And now when I execute the same select statement again, here we can see that this time we will see a clustered indexCant operator. Now you may have a question that what is the clustered index? Well, a clustered index is the one in which the leaf node of the index is the actual data page itself. There can be only one clustered index per table because it specifies how records are arranged within the data page. A clustered index can means the SQL engine is traversing your clustered index in search for a particular value or a set of values. It is one of the most efficient methods for locating a record bit by a clustered index C. Now stay tuned with us as in the next video we will be going to learn about our next operator index C.