Thursday, May 28, 2020

Define a new Data Structure from one that is nested

using nested data structures in likeds

In the past I have written about nesting data structures, a way to contain data structure(s) within another data structure. And there are times I have wanted to define a new data structure to be identical to another using the LIKEDS keyword.

01  dcl-ds One qualified ;
02    OneSF1 char(1) ;
03    dcl-ds Two ;
04      TwoSF char(5) ;
05    end-ds ;
06    OneSF2 char(1) ;
07  end-ds ;

08  dcl-ds Test1DS likeds(One) ;

Wednesday, May 27, 2020

Improvements to RPG's timestamps

improvements to rpg timestamp

Ever since timestamps were introduction to RPG I have always felt aggrieved that they never contained the entire timestamp. Timestamps have six decimal places following the seconds and only the first three positions, milliseconds, were filled. The last three positions were always zero. Occasionally I have found in timestamp fields in two records with same value. I would unable to determine which record is older, without using other fields or the file's relative record number.

The latest round of new Technology Refreshes, IBM i 7.4 TR2 and 7.3 TR8, brought improvements to the way RPG does timestamps.

Some of what I am going to describe here may have been available in earlier releases or TRs.

Tuesday, May 26, 2020

Key data structure big improvement

change to RPG %kds

I do not use the Keyed data structure, but I can appreciate this change that occurred as part of the latest new Technology Refreshes, IBM i 7.4 TR2 and 7.3 TR8, was significant.

Before the latest TRs the second parameter of the %KDS built function had to be a number to denote how many of the key fields were to be used. The change in the new TRs now allows for that second parameter to also allow a variable.

The old way would look something like this:

01    if (NbrKeyFlds = 1) ;
02      chain %kds(FileKeys:1) TESTFILER ;
03    elseif (NbrKeyFlds = 2) ;
04      chain %kds(FileKeys:2) TESTFILER ;
06    endif ;

Wednesday, May 20, 2020

Retrieving information about a library using SQL

new table function library_info to get library data using sql

As part of the new Technology Refreshes, 7.4 TR2 and 7.3 TR8, came a table function to return information about a single library. I have to admit that I don't really care about some of the information returned in the results, but there are three columns I am going to find very useful.

The new table function LIBRARY_INFO is found in the library QSYS2. It combines data elements from the RTVLIBD and DSPOBJD commands. When calling this table function there are two parameters, one mandatory and the other is optional:

  1. Library name:  No surprise that this is the mandatory parameter
  2. Ignore errors?  What to do when an error is encountered. This is the optional parameter. Valid values are: YES and NO

In these examples I am not going to use the second parameter.

Right, let's jump right in and see what information we can retrieve about one of my libraries:

Friday, May 15, 2020

Today is 7.4 TR2 and 7.3 TR8 day

today 7.4 tr2 and 7.3 tr8 ptf are available

Today is the day the PTFs for the latest Technology Refreshes are available for download, IBM i 7.4 TR2 and 7.3 TR8.

The relevant PTFs are:

You can find links to what are in these Technology Refreshes here.

I am now going to generate a support ticket asking RZKH to load these TRs on their partitions. When they have I can start sharing how to use these enhancements.

Wednesday, May 13, 2020

Discovering the database's limits

using sql to see the maximum sizes of the ibm i database

Every so often I stumble across something in Db2 for i that I may not have a practical use for, but I find interesting. The SQL table SQL_SIZING is a good example of this. It contains one row for each limit of the IBM i Db2 database manager.

The table contains just four columns:

  1. SIZING_ID:  The ANSI, and ISO, number that defines the database sizing id
  2. SIZING_NAME:  The ANSI, and ISO, database sizing id name
  3. SUPPORTED_VALUE:  Sizing limit (value). If null the sizing limit is not applicable for IBM i
  4. COMMENTS:  Even though the sizing name is big enough to contain an adequate description of the sizing id this column gives a more detailed description

Wednesday, May 6, 2020

Adding RPG compiler parameters into the SQL Option statement

sql option compileopt in sql rpgle program

This feature was brought to my attention by someone who was converting a fixed format SQLRPGLE program to modern all free RPG code, and wondered the purpose of this code snippet.

03  C+             COMPILEOPT = 'DBGVIEW(*ALL)'

She understood the purpose of line 2. It was line 3 she had not seen before. Neither had I, and was intrigued as to what its purpose was and how else could it be used.

Tuesday, May 5, 2020

IBM performance FAQ update

The latest updated version of IBM's "IBM i on Power – Performance FAQ" was published at the beginning of this month, May 1.

While it includes the usual system information, in the latter half it contains advice for:

  • Db2 for i
  • RPG
  • Cobol
  • C
  • Java

To view the guide, which is a PDF, click here.