What type is guid

What is GUID? We use GUID for unique identifier. Why do we use GUID? A GUID makes a great primary key in the back-end database. While each generated GUID is not guaranteed to be unique, the total number of unique keys 3. For an application using 10 billion random GUIDs, the probability of a coincidence is approximately 1 in a quintillion.

A common approach is to create an auto-incrementing integer; another way would be to create a GUID for your products. Find centralized, trusted content and collaborate around the technologies you use most. Connect and share knowledge within a single location that is structured and easy to search. Is it a number or string?

Also, is there a big performance hit when using GUID as primary key? Besides the problem with clustering mentioned here: What are the best practices for using a GUID as a primary key, specifically regarding performance? I think it should be bit number as described here , but I cannot find mode details on how is it implemented in SQL server.

If you plan to use GUID , use uniqueidentifier instead of varchar as data type. Microsoft did not mention how they implement it, there is some speed optimization when you use uniqueidentifier as the data type. If you must store it as a string, the length really comes down to how you choose to encode it. As hex AKA base encoding without hyphens it would be 32 characters two hex digits per byte.

Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Ask Question. It is easier to make operations and references to this text field using the GUID data type than it is using the textual representation.

The GUID data type is compatible with the existing textual representation. The GUID data type is useful when you want to uniquely identify some data, so that it can be exchanged with external applications.

For example, if you want to transfer an item catalog to an external application, you add a GUID field to the record in the table and use this as the primary reference when you communicate with the external application. This function creates a new unique GUID value. This function is a convenient way to check if a value has already been assigned to a GUID. When you create a new record, a valid GUID is created and assigned automatically.

If the result is assigned to a TEXT variable or field, the value is converted to a string and follows the syntax explained earlier. This function does not accept a Text value as an argument. It nullifies the GUID value in the same way as it resets any other value. AutoSplitKey is a property, not a function and can be applied to pages.