In the early days of DB2 for z/OS, pretty much every change to a table would result in an unload-drop-recreate-load of the table. This article will talk about how the ALTER table in DB2 12 for z/OS has evolved from DB2 11 for z/OS and what you need to know from a practical point of view.
In DB2 11
In Part 1, I talked about some of the first steps that a developer should go through when it comes to tuning queries. In this article, I will go through the initial steps in evaluating a SQL query using the Db2 explain output.
Vamos a comenzar esta discusión de manera sincera – Soy un gran fan de la cláusula de SQL FETCH FIRST n ROWS ONLY. Esta sentencia requiere un poco de clarificación debido a que existen varios casos de uso y otros que no hacen mucho sentido. De cualquier manera, voy a intentar el no complicar la disc
When it comes to tuning a query, program, or even an application that most developers are not sure where to begin or what may be causing response time issue(s). This article is here to help!
Locking and latching are both key mechanisms employed by relational database management systems to ensure data integrity, consistency, and the serialization of resources. In the Db2 for z/OS IRLM manages the locks, but both Db2 and IRLM have internal latches.