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.
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.
No quotes: Case insensitive. Asterisk is not allowed.
Single quotes: Case sensitive. Asterisk is interpreted as Char(42).
Double quotes: Case insensitive. Asterisk is interpreted as a wildcard.
Does this also mean that, we still don't have an option to perform direct 'case sensitive wildcard search' in set analysis? That would have been a great plus.
Could anyone clarify one thing please? For the old expressions in the old version of QlikView, after we upgrade the QlikView server to the November 2017 version, will they work or not work.
If they will not work, we will have to check through all the expressions before we upgrade QV, is that correct?
tresesco chr(42) would mean that an asterisk would be interpretted as a literal character. So if you write ={'David*'} that would only return records where the asterisk is part of the field value itself. The asterisk won't be treated as a wildcard.
Will this also fix "parameter parsing" when I want to inject a SET ANALYSIS via $1 into a variable?
Today Qlik always splits parameters with ever comma. Even when I use escape parameters to hand over for example Year={2015},Country={AT} to the variable. See examples below
I'm aware of some workaround to overcome the issue [ Use the (A|B|C) Syntax for multiple values; replace comma, hand over a variable that contains the SET]; but still it would be so much easier to use and maintain if Qlik could come up with a solution here.
In my imagination we can at some point use this feature to hand over parameters to MASTER ITEM expressions. This would help so much to provide "SELF Service Experience", without creating dozens of MASTER ITEMs where just the SET-part is different...
Alternatives are there I agree. With double quotes, we would be able to search, but that is unfortunately case-insensitive. Case sensitive match (read-'no search') would be possible using single quotes. That way, we are left with only 'case sensitive search (read wildcard)'; and that is not there. Yes, indirect solutions are there.
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