What I'm Thinking

Dummy VSM Dataset in JCL
20 January 2012

In general we use DUMMY datasets in JCL instead of a actual file for some requirements. But how can we specify dummy VSAM dataset in a JCL? The parameter AMP=‘AMORG’ tells the OS to treat the file as VSAM file. //NOVSAMIO DD DUMMY,AMP=‘AMORG’

20 January 2012

In Temporary Storage Queues Data is read randomly, while in Transient Data Queues data must be read sequentially. In a TSQ data can be read any number of times as it remains in the queue until the entire Queue is deleted. In TDQ data item can be read once only. To reuse the TDQ it must be closed and reopened. Data can be changed in TSQ, but not in TDQ. ... Read More
The Easiest and Coolest way to locate bad data is thru File-Aid’s FIND command. OPEN the file in FILE-AID (in either browse or edit mode). XREF with COPYBOOK. Use FMT mode. Then issue the below command. F /field-name INVALID or F /field-number INVALID The control will take you to the first invalid data record for the given field. Example: The FILE has 3 fields namely NAME,AGE,COUNTRY. ... Read More
NULLs can present problems because they are handled differently by different computers and the collating sequence is inconsistent with regard to NULLs. Unless you specify NOT NULL, the default is to allow for NULLs. It’s easy for us to get lazy and allow columns to contain NULLs when it would be better to specify NOT NULL. Allowing for NULLs will create UNKNOWN logical values. Always test your code with NULLs in all possible places. ... Read More

Explanation on DB2 Explain
19 January 2012

When an SQL is executed against or bound to a DB2 database, DB2 Optimizer tool defines the access path used to access the data. This access path is defined according to tables’ statistics generated by DB2 Runstats tool. The Explain command details the access path defined by DB2 and allows you to analyze how the data will be accessed and how you can improve the command’s performance. A table called PLAN_TABLE which has your user id as its owner is required for working on DB2 Explain. ... Read More