In the past week one of my established jobs has started an "object locked" error. After some quick analysis I discovered that the object in question is a file in the QDLS file system. This left me asking myself a couple of questions
Data structures have always been a useful part of RPG, especially when returning information from a procedure. In CL I can create "Defined Variables", which are the equivalent of a RPG data structure. This becomes useful when I have a CL procedure that is called by RPG procedure, or vice versa. I will explain that in detail in a future post.
I am sure we have all encountered a situation where a data structure is passed to a CL program, and I have seen many programs were the subfields are broken out into individual variables using the Substring command, %SST. While this is easy if the data structure contains only character subfields, it can get messy if there are numeric subfields as I have to determine the start and end positions while considering the packing of the number.
Operation code extenders on a Read operation in RPG are those letters that are follow the operation code in parentheses. I am sure the two most commonly known ones are:
read(e) TESTFILE ; reade(n) (KeyField) TESTFILE ; |
Each one provides a little bit extra functionality that compliments the Read operation. On performing research for this post I found that with free format Read operations a number of additional extenders were added, some are available with only some of the Read operations in V5R4 and later releases.
Almost by accident I have started discussions on how to determine the largest objects on your IBM i server. I have given examples of how:
In last week's post, here, I gave an example of how I determine the 250 biggest objects on my IBM i server. I created the information about the objects by using the Display Object Description command, DSPOBJD, and mentioned if anyone knew of a better way to get the same information to contact me.
There are times when I do not want all of the rows/records from a table/file just, for example, the 100 with the largest value in a variable. I could use a "Copy File" command, CPYF, to copy on the first 100, but I cannot sort with a CPYF to select the largest. Fortunately SQL's Select does offer me a way to do this.
Today did not start well as the development server reached critical storage, 93%+ of DASD was being used. After doing some basic deleting and purging of a few files I was not able to lower the percentage of DASD more than 1%, which was not enough. What I need to do was to identify the largest object on this IBM i and determine if they could be deleted or their contents purged. But how to find those big objects?
Last week I discussed how to use control block size in the "Override with database file" command,OVRDBF, see here. In this post I am going to introduce the SQL procedure OVERRIDE_TABLE. Unlike the OVRDBF command this procedure can only do one thing, set the control block size for a table/file.
The OVERRIDE_TABLE appears to have introduced in IBM i 7.1 TR7. It is not mentioned in the IBM i 7.1 KnowledgeCenter website, but is in the 7.2 site.
This procedure has only three parameters:
IBM i 7.1 TR7 saw an addition to the "Override with data base file" command, OVRDBF, the ability to set the control block size when performing file I/O. By increasing the control block size I can increase the memory allocated to the file's I/O buffer, which will increase the speed of I/O to the file. The enhancement is to the second element of the "Limit to sequential only" parameter, SEQONLY.
Limit to sequential only: Sequential only . . . . . . > ____ *NO, *YES Number of records . . . . . > _________ Number, *BUF32KB, *BUF64KB... |
I know I have written a lot recently about SQL, but IBM has added a lot of great views that allow you to access information easily. A good example is today's post: how to get information from a job log using SQL. Prior to this if you need to get information from the job log you had to use the RCVMSG command or the "List Job Log Messages" API, QMHLJOBL. Now I can get the information I want just using a SQL Select statement.
The JOBLOG_INFO table function was added to IBM i 7.2 and 7.1 TR9. It returns one row for each job log message, and what I really like about it is I can choose what information to return by using a WHERE clause in the Select statement.
This presentation was made by Birgitta Hauser, IBM i SQL expert, to Common Europe on May 28.
The latest Technology Refreshes for IBM i, TR2 for 7.2 and TR10 for 7.1, are available today to download. You can learn more about them from IBM's developerWorks web site here.
You can learn more about what is in these Technology Refreshes from these posts:
We have been given a number of SQL views that allow us to harvest information from our IBM i's, and many are unaware of their existance.
With the move from DDS files to SQL tables, indexes, and views I needed to update my toolset to be able to list information about the last two in a quick to run and easy to read way. Fortunately I can use some of these views to do so: