Tuesday, October 19, 2021

How Do You Store Boolean Data in Db2?

Recently, I was reading an article written by Ben Brumm on using Boolean data in SQL and it got me thinking about Db2 and Boolean data. You see, if you click over to the article, you'll see that Ben talks about several popular database systems, but not Db2!

So first of all, what is Boolean data? Sometimes all you want to do is to be able to store a Yes/No, True/False, 1/0 value in a column of a Db2 table. But that can be problematic. What data type should you choose? How should you model that column? Does it matter?

Well, up until recently, Db2 did not support a Boolean data type. But I guess I should be more clear: Db2 LUW offers Boolean support, but Db2 for z/OS does not have a built-in Boolean data type.

As of V9.7, you can use a Boolean data type for local variables, global variables, parameters, or return types in compound SQL (compiled) statements. So it is really only a viable option for SQL PL. As of V11.1, you can use the Boolean data type for a column in a Db2 table.

OK, so what should you do if you do not have Boolean support in the Db2 you are currently using? In my opinion, the best approach is to use a numeric solution with 1 as TRUE and 0 as FALSE. You might want to consider using a Character column with YES/NO or TRUE/FALSE, but there are several issues with that approach. Firstly, it will likely consume more storage, secondly without a constraint on the column users might specify “YES” or “Yes” or “y” or “Y”… or other variations to mean the same thing, and finally, if English is not your first language then users may have the urge to specify “Si” or “Da” or… well, you get the idea.

A good choice for a Boolean data type could be BINARY(1) which only stores binary data, so no constraint is needed. Or you might want to specify SMALLINT with a check constraint only allowing 0 and 1 as options.

If you want to allow "Unknown" as an option, then you can make the column nullable.


So, share your experiences with us here on the blog. Tell us, have you implemented Boolean data in your Db2 tables? How did you do it? And how is it working out for you? 

Monday, October 11, 2021

What is Db2?

For regular readers of this blog the title of this particular post might seem to be a bit odd. After all, why visit the Db2Portal blog if you don't know what Db2 is, right?

Well, the purpose of this short post is to refer my regular readers to an article I wrote for TechTarget, a website that regularly posts "What Is" type of articles.

So, you guessed it, I wrote the latest, updated "What is Db2?" article for TechTarget... and I figured I'd share it with my blog readers. 

Now whenever somebody asks a high-level question about Db2, like "what is it?" or "what are the advantages and disadvantages of Db2" or even "where can I run Db2?" you now have a place to send them...

Here ---> What is Db2?

Monday, August 30, 2021

What Type of Changes Cause Db2 Packages to Get Invalidated?

Db2 DBAs are constantly working with database objects such as Databases, Tablespaces, Tables, and Indexes. And many requirements cause DBAs to have to modify these objects. Some modifications may be simple, such as just issuing an ALTER statement. Others may be more in-depth, even to the point of having to DROP and re-CREATE the object.

Now I've blogged here before about the many different types of Db2 database changes and how to manage them. For reference, here is a blog post that summarizes the posts I've made on this topic.

My purpose today is not to rehash all of that information again, but to discuss one aspect of change management that probably causes DBAs the most grief: package invalidation. 

Packages can be invalidated by Db2 for many reasons. For example, when a privilege that is required by a package is revoked, the package is invalidated by Db2. 

When a package is invalidated it cannot be executed until it has been rebound. This can be automatic, but it is usually better to be proactive and to Rebind packages when you take an action that invalidates packages. 

And as we all know, rebinding can cause access paths to change. Hopefully for the better... but not always. If access paths always got better then there would be no DBA grief, right? Whenever DBAs perform Rebinds they are always dreading that call from the developer or end-user that says "Hey, this transaction (or job) that used to run quickly is now taking forever."

So it makes sense that DBAs need to be aware of what changes cause packages to be invalidated. Of course, if you have to DROP an object that the package accessed it is obvious that a Rebind is required. But there are many other types of changes that will invalidate packages.

Fortunately, the IBM Db2 documentation is good and easy to find. Here is a link to the Db2 12 for z/OS documentation for Changes that invalidate packages. If you are a DBA, I recommend that you click on that link and bookmark that page!

I'm not going to copy and paste all of the information from the manual here (no reason to and over time it could change). But here are some of the things to keep in mind that you may not at first think will affect packages, but can:

  • Altering, dropping, or renaming a column
  • Adding date/time columns with defaults
  • Adding a constraint
  • Adding, changing, or rotating partitions in a partitioned or partition-by range UTS tablespace
  • Temporal and transparent archiving changes
  • Adding, altering, or dropping a materialized query table (MQT) 
  • Activating or deactivating row-level or column-level access control
  • Enabling or disabling masks if column access control is in effect
  • Increasing a table space's MAXPARTITIONS attribute
  • Changing a table space's SEGSIZE or DSSIZE
  • Changing the buffer pool for a tablespace (with a different page size)
  • Altering indexes to add a column, change the PADDED attribute, or changing the limit key value of a partitioning index
  • Regenerating an index
  • Running the REORG utility with the REBALANCE keyword
  • Running the REPAIR utility on a database with the DBD REBUILD option

Again, these are just some of the admin changes that can invalidate packages. There are others and you should always refer to the current Db2 documentation for the list of things that will invalidate packages before you make any changes. Failing to do so might mean that you will have to run a mass Rebind... maybe at a time when you'd rather not!

Finally, I'll leave you with a couple of helpful queries you can run to help as you manage changes.

To identify all packages that will be invalidated by a change to a specific object, run the following query:

AND      BNAME = ?
AND      BTYPE = ?

Simply plug in the qualifier and name of the object, along with type of the object (appropriate values can be found in the Catalog table documentation in the appendix of the IBM Db2 SQL Reference manual).

And if you want to identify all invalid packages, try running this query:


Monday, August 16, 2021

SQL to Return the nth Maximum Value

Sometimes what seems like a simple request might take a little bit of thinking to devise and implement a solution. Recently, I was asked how to write SQL that returns the nth maximum value from a column. If you think about it, it isn't too difficult.

Assume that you have a table with 10 rows, and there is a column in that table that holds the values 1 through 10. The idea is to create a query that for the 7th maximum value would return a 7, the 8th an 8, and so on.

This can be accomplished with a common table expression (CTE) and the following query:


Simply change the value of FETCH FIRST from 7 to whatever you wish n to be.

If there are duplicate values and you want to eliminate them from consideration, just change the SELECT to SELECT DISTINCT in the TOPN common table expression.

This should work for any type of values (numeric, character, date/time) that you wish to query.

Thursday, July 29, 2021

New IBM Storage Systems Boost Ability to Gain Value from Your Mainframe Data

Gain more value from your mainframe data with IBM Storage

Every year the amount of data that is created continues to expand. Analysts at IDC estimate that data will grow at a compound annual growth rate of 23 percent through the year 2025Furthermore, efficient access to critical business data can mean the difference between success and failure, yet we sometimes forget about the crucial role that storage systems play in our everyday business transactions.

While storage systems have gotten more intelligent and fault-tolerant over the years, there’s always room for advances that can deliver an improved user experience. This can be seen by IBM’s latest storage announcements. The announcement highlights new and improved storage capabilities including cloud-like consumption models, data resiliency, and mainframe storage. This post will focus on the mainframe aspects of the announcement.

Why mainframe? Well, the platform continues to prosper and grow. According to the latest BMC Mainframe Survey, 90 percent of the IT leaders surveyed see the mainframe as a long-term platform for growth. The world’s largest organizations rely on the mainframe to deliver superior performance, reliability, and security. Mainframes are being used not just for traditional transaction processing and batch workloads, but also for new workloads running business analytics and AI applications on structured data. Not to mention that these large shops store most of their data on the mainframe!

What’s New

On July 20, 2021, IBM announced the next generation of its Storage for the IBM Z, the IBM DS8980F analytics class storage system. Engineered to excel for modern workloads that span transaction processing, analytical processing, and AI for native cloud and on-premises computing. The DS8980F offers high-speed and high availability as a single all-flash storage solution.

As part of this announcement, IBM is introducing improvements in Safeguarded Copy to the entire family of IBM DS8900F systems – including DS8910F, DS8950F and the new DS8980F – to greatly reduce the recovery time from a remote location to the production environment. Additionally, IBM is bringing the Safeguarded Copy function in IBM Spectrum Virtualize software to the IBM FlashSystem family and IBM SAN Volume Controller. 

Bringing the focus back to the mainframe: the new IBM DS8980F storage system has been developed by IBM with its z15 mainframe hardware in mind. That means it is optimized for mainframe-class workloads. Organizations are continually looking for ways to improve the performance of their mainframe applications, and the DS8980F provides the fastest mainframe application response times. Therefore, a key method of improving performance can be to upgrade your storage system. Indeed, the new IBM DS8980F, compared to the last generation of IBM storage systems (DS8888F series), can improve response time by up to 25 percent. 

Minimizing downtime is another critical requirement of modern business applications, especially for those that run on mainframes. The new IBM DS8980F delivers 7 nines of availability (99.99999 percent), an improvement of 10x over the previous generation.

Additional improvements include more than twice the amount of system cache and greater bandwidth capacity, all while requiring less energy consumption and in a lighter-weight box.

At the same time, IBM also announced a new tape library system, the IBM TS7770, with all flash cache. The most significant new feature of the TS7770 is that it provides better performance with only 1 flash drawer than the previous 10 SAS HDDs drawers, delivering faster data protection with less infrastructure.

Finally, it is possible to combine the TS7770 tape library and the IBM DS8910F  (the entry version within the DS8900F family) into a single 19-inch industry-standard rack. This enables smaller and medium-sized organizations to deploy an end to end storage solution for mainframe environments, into a smaller amount of floor space with important savings in operating costs.


Data growth continues unabated, and organizations continue to use mainframes expecting them to deliver unparalleled performance and availability for their mission-critical workloads of all types.

To achieve this level of performance and availability, while managing data growth, organizations need the latest and greatest storage technology. And IBM’s latest DS8980F and TS7770 will help organizations achieve the performance and availability they require for all their application workloads.

If you’d like to learn more about the latest from IBM storage, you can read the full details in the IBM announcement.