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Henric_Cronström

Today, the Qlik engine has some bugs in the area of a search and a subsequent select. These affect both interactive searches and searches in Set Analysis expressions. We are working on fixing them. However, one of these coming bug fixes may cause some backward incompatibility. This post explains what the bug fix will mean, and what you can do to avoid future problems.

When you use Set analysis, you can choose to have a condition in the form of a list of values in the Set expression, or you can choose to have a rule-based definition - a search for field values.

Examples of hard coded lists:

Sum( {$<Year = {2013,2014,2015}>} Sales)
Sum( {$<Country = {'Australia','Canada','France'}>} Sales)

Examples of searches:

Sum( {$<Year = {">=2013"}>} Sales)
Sum( {$<Country = {"Austr*"}>} Sales)
Sum( {$<Customer = {"=Sum(Sales)>100000"}>} Sales)

All the above constructions work today, and they will work correctly also after the bug fix.

Note the double quotes in the search expressions. These define the search strings, and between them you can write any search string – the same way as you would in a list box search.

However, you should not use single quotes to define a search string.

Single quotes are reserved for literals, i.e. exact matches. Hence they should be used when you want to make a list of valid field values, like the above list of explicit countries. But they should not be used for searches. Single quotes imply a case sensitive match with a single field value.

This difference between single and double quotes has been correctly described in the reference manual that states that searches are “always defined by the use of double quotes”. Also, all examples with literal field values in the documentation use single quotes.

Now to the bug: QlikView and Qlik Sense currently do not respect the above difference between single and double quotes. Instead, strings enclosed in single quotes are interpreted as search strings. As a consequence, it is not possible to make case sensitive matches with field values, something which you sometimes want to do.

This bug will be fixed in the coming November releases of Qlik Sense and QlikView. Then, wildcards in strings enclosed by single quotes will no longer be considered as wildcards. Instead, the strings will be interpreted as literals, i.e. the engine will try to match the string with a field value containing the ‘*’ character. The same logic will apply also to relational operators and equals signs.

Unfortunately, this bug has been incorrectly utilized by some developers: I have seen Set Analysis expressions with correct search strings, but erroneously enclosed in single quotes; for example

Sum( {$<Country = {'Austr*'}>} Sales)

This search should instead have been written

Sum( {$<Country = {"Austr*"}>} Sales)

Hence, there are documents with expressions that will not work in the corrected algorithm. However, the bug fix will be implemented in such a way that old documents will use the old logic, and new documents will use the new logic. In addition, it will be possible to force the new logic for all documents by using a parameter in Settings.ini.

You can of course also change the single quotes in existing search strings to double quotes, and the expression will continue to do what it always has done.

This post is mainly to give you a heads-up on a coming change, and give you a chance to make a quality control of your own documents. We will publish more information as we get closer to the release.

HIC

 

Further information related to Set Analysis and Searches:

The Search String

Introduction to Set Analysis (video) - Part 1

Set Analysis - Part 2 - Cool Stuff You Can Do (video)

61 Comments
rajareddyjkl
Contributor III
Contributor III

Thanks Henric ...

0 Likes
6,323 Views
Anonymous
Not applicable

, ... really great!

0 Likes
6,323 Views
sunny_talwar

Wow, this will make our life somewhat difficult in a way that we might need to go back to fix a lot of places .... I totally didn't think about this

6,310 Views
vgutkovsky
Master II
Master II

Thanks, Henric. Can you please expand on this:

However, the bug fix will be implemented in such a way that old documents will use the old logic, and new documents will use the new logic

Is an "old" document one that was originally created with an earlier version of QlikView, even if it is subsequently modified with QlikView 12.10? Under what circumstances would the old syntax in "old" documents stop working? What about user-created expressions that are housed in Shared files, would those always be considered "new" even if the Shared file belongs to an "old" document?

I'm particularly concerned with the functionality break that Gysbert mentioned above. I probably have thousands of expressions in production among my various clients that use simple nested single-quote searches.

Thanks,

Vlad

6,310 Views
Henric_Cronström

gwassenaar , vgutkovsky and stalwar1 :

You will not need to change old documents.

Each document contains information about which version that created it. And this information will be used to determine which logic to use. It will not matter if you modify it, change expressions or add collaboration objects. An "old" document will remain old.

6,310 Views
Henric_Cronström

gwassenaar

You are absolutely right that if you have nested quotations, you may need to use all three quoting possibilities: "..", [..] and `..`. All three can be used to define a search.

6,310 Views
tresesco
MVP
MVP

That's a big relief.

Each document contains information about which version that created it.

Wow! Thanks Henric; thanks Qlik.

6,310 Views
sunny_talwar

Oh wow!! this is a huge relief!! Thanks for the clarification hic

0 Likes
6,310 Views
godfreydaniels
Contributor III
Contributor III

Each document contains information about which version that created it. And this information will be used to determine which logic to use. It will not matter if you modify it, change expressions or add collaboration objects. An "old" document will remain old.

Besides the forthcoming bug fix, how else is this version info used?  If I add the same expression to two documents on the same day--one old, one new--it seems I cannot expect it to behave the same in both.

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vgutkovsky
Master II
Master II

That's a relief thanks! When you wrote that the purpose of this post was to "give you a chance to make a quality control of your own documents" I got a little scared.

Follow-up questions:

1. What does "old" mean? Docs created in version 11.20? Or even earlier releases of 12?

2. Since QlikView clearly has the ability to decide which syntax to apply to which documents, does that mean we can use settings.ini to force even new documents to the old syntax?

Thanks,

Vlad

0 Likes
6,234 Views