As you probably know, online schema evolution (sometimes referred to as “online schema change”) was one of the key new features of DB2 V8. But, as its name implies, its capabilities continue to evolve. With V9, online schema evolution expands to simplify more types of database definition changes. The new term IBM is using for this in V9 is Database Definition On Demand (DDOD). One of the nice new components provided by DDOD in V9 is that online table space reorganization is significantly improved. Today, when reorganizing just a couple of partitions...
Monday, 30 April 2007
Thursday, 19 April 2007
SELECT from DELETE, UPDATE, and MERGE [DB2 9 for z/OS]
Posted on 13:50 by Unknown
Another nice new SQL feature provides the ability to SELECT from DELETE, UPDATE, and MERGE statements.This capability is similar to the SELECT from INSERT feature that was introduced with DB2 V8. So, before looking at the new V9 feature, let’s review the V8 feature.The ability to SELECT from an INSERT statement is an intriguing feature. To understand why this is so, we need to review some background details. In some cases, it is possible to perform actions on an inserted row before it gets saved to disk. For example, a BEFORE TRIGGER might change...
Tuesday, 17 April 2007
Free DB2 Access Paths Webinar - April 18, 2007
Posted on 09:37 by Unknown
Just a quick note to inform my readers that I will be conducting a webinar tomorrow - Wednesday, April 18, 2007 - on the topic of Change Control for DB2 Access Path Selection. The session will start at 10:30 Central time and will last about an hour. To register, click on the link above.Here is a short description of what I'll discuss: Most changes are strictly controlled in the mainframe environment. But that is not the case for DB2 access paths. When we BIND or REBIND a program, DB2 formulates access paths “on the fly” and we do not have any control...
Tuesday, 10 April 2007
MERGE and TRUNCATE [DB2 9 for z/OS]
Posted on 11:21 by Unknown
Two additional new SQL statements available in DB2 Version 9 are the MERGE and TRUNCATE statements.MERGEThe MERGE statement basically takes two “tables” and merges the data into one table. The table that will contain the merged results is referred to as the target; the other participating table is called the source. Rows in the target that match the source are updated and rows that do not exist in the target are inserted from the source to the target.If you use other DBMSs you may be somewhat familiar with MERGE functionality. It is sometimes called...
Monday, 9 April 2007
New DB2 9 Security Redbook
Posted on 07:09 by Unknown
Just a quick entry today to alert everyone that there is a new DB2 for z/OS redbook available on the topics of regulatory compliance, security, and audit. The redbook is titled Securing DB2 and Implementing MLS on z/OS and you can download it for free today over the web.The redbook is 360 pages (including index) and covers the plethora of new security features in DB2 for z/OS. If you haven't looked at DB2's authorization and security functionality in awhile there is much to learn... and this redbook will be very illuminating.That's all for tod...
Thursday, 5 April 2007
Native XML Support in DB2 Databases [DB2 9 for z/OS]
Posted on 12:24 by Unknown
One of the biggest technological advances in DB2 V9 is the ability to combine the management of structured and unstructured data. Basically, V9 will allow you to store data as native XML. This capability has already been introduced into V9 of DB2 for Linux, Unix, and Windows.Many of you may well ask “Hey, what’s the big deal here? Can’t we already use the XML Extender and store XML data in DB2 prior to V9?” Yes, but V9 changes the game. You will be able to search and analyze structured data in a relational data repository and unstructured data...
Wednesday, 4 April 2007
ORDER BY and FETCH FIRST in Subselects [DB2 9 for z/OS]
Posted on 14:06 by Unknown
Here is another quick post in my series on new features in DB2 9 for z/OS.Today, we will look at the additional flexibility gained in how the ORDER BY and FETCH FIRST n ROWS ONLY clauses can be specified in V9. Prior to the V9, the only place you could specify these clauses was at the statement level. Indeed, this has been a source of confusion for many DB2 SQL programmers.A discussion of DB2 SELECT should be broken down into three topics:fullselect, subselect, and select-statement. The select-statement is the form of a query that can be directly...
Tuesday, 3 April 2007
INTERSECT and EXCEPT [DB2 9 for z/OS]
Posted on 11:14 by Unknown
With this blog entry I am introducing a new series in which I will briefly blog about the new feature of DB2 9 for z/OS. Today's entry will cover the new INTERSECT and EXCEPT keywords.DB2 for Linux, Unix, and Windows has supported INTERSECT and EXCEPT in SQL SELECT statements for quite some time now, and with V9 the z/OS platform catches up. These two set operations can be used to simplify some SQL statements. Think of them as being similar to the UNION operation.INTERSECT is used to match result sets between two tables. If the data is the same...
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