The Jacana Collection
  . December 17th 2002 - Issue 4  
. . . . . . . . .


Welcome to the final edition of Jacana eNews for 2002. In this edition we look at how subset design can affect the performance of your report run-times and provide some tips for improving subset design. Our FAQ looks at how you can generate and print a sequence number for your print lines. Once you know how, this is a simple task and is also good background to understanding creation of 'Top-10 Ranking' reports - a topic that will be covered in the New Year.

Don't forget to refer to the Archive for any back issues and let us have your feedback on topics or issues you'd like us to cover in 2003.

To all of our readers we wish you every happiness this Holiday Season and prosperity and good health in the New Year.

Rachel Brooks
Editor, Jacana eNews
Momentum Utilities

In this Issue
Something for the festive season!
We thank all our customers for working with us during 2002 and invite you to click on the link below to view our humorous Christmas Greeting! 

We know many of you have already visited our special Christmas web page and from the emails we've received you all seem to have taken it in the spirit that it was intended. We have had a few requests to publish the original recipe upon which the cartoon was based. This can now be found on the Christmas web page ... if you only have access to a slow line then this is an alternative fun piece!

Link to the Christmas Web Page!


Effective data subsets improve report run times 
One of the areas where our Professional Services team has been able to assist clients is in optimising the way subsets are designed. We have had a couple of cases where we have been able to review subset design and, as a result, have managed to show the client how to cut run times from several hours to a few minutes - just through better subset design! 

In one recent case, we looked at a Subset which was based on a very low volume file, linked one-to-many to another very low volume file and from there, linked one-to-many to a relatively high volume file. There were a number of other less significant links. 

In this instance, we were able to achieve a major performance improvement by "inverting" the structure. The replacement Subset we provided used the above high volume file as its based-on-file and linked one-to-one to the two low volume files. 

This technique will usually deliver a significant performance benefit while imposing some restrictions on the range of possible reports. In most cases, it is fair to estimate that the second structure will facilitate most, but not all, of the reporting possible from the first. However, for those reports that the Subset can support, the performance benefit is often dramatic - in this review we achieved a saving in run time of over 90%. There is, of course, no problem in having both Subset structures available - providing that some user information (eg. user notes attached to each Subset) is in place to encourage the correct choice, on the part of the Jacana user, of the data source for a given report. 

Click here for some tips on Subset design

If you are concerned that any of your OPEN/DB based reports seem to take a long time to run why not contact us? For no cost we will investigate a report of your choosing and, hopefully, make suggestions on how to improve it's performance. For a modest fee we can help you with an audit of your reports and subsets. You could be in for a pleasant surprise!


Ask the expert - Jacana Tips

If there's anything you'd like to know how to do in Jacana but aren't 100% sure how, ask us. We will respond to you immediately and look to share your question in a future newsletter. 

Jacana Tip 11: Although Jacana let's you save reports locally while you are working on their definition, you must save a report to the iSeries server before you will be able to run the report. The report name that you use when you save a report locally does not have to be the same as the name of the report on the iSeries server. To change the name of the report on the server, choose Properties from the Report menu. 

Jacana Tip 12: You can condition lines in the layout to print only under specified circumstances. From the Layout menu, choose Line Properties and then select the Conditioning tab.

Jacana Tip 13: A quick way to invoke help about Jacana is to double-click in the left-hand pane of the status bar.

Jacana Tip 14: You can view statistics about a report you loaded from the server, such as the average time it takes to run the report. Choose Properties from the Report menu and then select the Statistics tab.


Technical FAQs

Generating and printing a sequence number for your print lines

As a "stand-alone" feature, this is not a common requirement, but it does arise. More importantly, generating a number for each successive detail print line on the page has application as a component in building such reports as "Top-10-Ranking" reports. 

In our next feature, we will be showing you how to build a "Top-10-Ranking" report. The ability to generate a number for your detail print lines will be "assumed knowledge" in that article.

Before we start, it is important to be sure that you understand what a "data-group" is in the context of the report writer. If you are quite sure that you do, read on. If not, perhaps you have heard the term but are not quite sure what it means - maybe you've never heard it,  for an explanation of Data Groups click here - it will make it easier to understand the following explanation.

The report writer does not "count" print lines as such. However, you can build a counter over one or more particular fields and print this on your report layout. For this example, we're using the training Subset supplied as part of all report writer installations - "DEMOINVENT". For more about the DEMOINVENT Data Group structure click here 

Our example report is going to print the products, and their stock values, within each warehouse. We will number each warehouse in the report and, within each warehouse, each product will be numbered. So, let's get started. 

Start the Jacana new report wizard and choose DEMOINVENT as your data source. Add the fields: "Warehouse Identifier" (WHID), "Product Number"(PRON) and "Extended Selling Price" (EXSP) to your working list. 

In the wizard sort dialog, choose "Warehouse Identifier" and then "Product Number" for your sorting and then click on "Finish". Jacana will design the report and show you the layout. We are now ready to define the counters that will enable us to print sequence numbers for each Warehouse and each Product. 

Open the report specifications dialog and add a new calculation (with Properties of Signed Numeric 3,0 with text "Warehouse Rank"). Condition the calculation WHY? as follows: 

*IF &WHID = ' '. Click OK then set the expression to 1. Now click on the "else" case, and set the expression there to 1 also. Now, you have a calculation that will hold the value 1 in all circumstances (i.e. when the Warehouse Identifier is blank and also when it is not). A Running total of this calculation field will give us the sequence we want to see on the report. 

Now create a second calculation, like the first, but testing "Product Number" in the condition (instead of Warehouse Identifier). Set the text to, "Product Rank". 

Now, via the Report Specifications dialog and the 'Summarize' tab, specify a "Running Total" for both these calculations then click on the "Summary Fields" button on the Data Crafter tool bar. You will see 6 running totals defined - one for each calculation at each sort level ("Report Level", "Change of Warehouse" and "Change of Product").

Drag, "Running total of Warehouse Rank for Report" and drop it beside the Warehouse Identifier field on the print line (Tip: Use the right-mouse to drop both the field and its column headings). Next, drag the, "Running total of Product Rank by Warehouse ID" WHY? and drop it beside the Product Number. Finally, use the "Format field" dialog to format the "Running total of Product Rank by Warehouse ID" to "Always Print" WHY?. Save and run this report and view the output. 

Note the sequence numbering beside warehouse and product.

NB: Dependent on the preferences you have set in Jacana your field names may appear differently in the Data Crafter. The field name WHID for Warehouse Identifier for example may appear as t00.FACIDN

Do you have any specific questions you'd like answered? Let us know 




We hope you enjoy this and future issues of Jacana eNews. Please send us your feedback and any suggestions or contributions for future issues.

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