Wildcards in tag filters sometimes show tags twice

Question

When using wildcards in tag filters, the searched tag is shown twice for some patterns.

For example

http://stackoverflow.com/questions/tagged/*facebook*

results in showing the Facebook tag twice:

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Another example showing the searched tag twice:

http://stackoverflow.com/questions/tagged/*magento*

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The issue seems to somehow depend on the tag being searched.

Other patterns, like:

http://stackoverflow.com/questions/tagged/*html*
http://stackoverflow.com/questions/tagged/*http*

work as expected. They do not show the searched tag twice.

Answer 1

This is a minor glitch caused by synonyms, which will be fixed in the next build; basically, after doing the expansion it finds some are synonyms, and does the replacements over the top - this means that some got duplicated. This will be fixed in the next build.

Example:

• "abc-def" is a synonym for the master-tag "abc"
• you search for "abc"
• it expands to "abc-def abc"
• it then applies synonyms, giving "abc abc"

The order "expand wildcards, then apply synonyms" is intentional, and addresses some edge-cases, i.e. if "ghi" is also a synonym of the master-tag "abc", then searching for "gh" will show you the "abc" data.

BTW, the explanation for this is much longer than the fix, which was just "add .Distinct()".

For info, the offending synonyms are shown here.

Answer 2

I believe it is a glitch in the search system (but it makes sense!!!)

Basically (what I think) it is doing is searching for all tags that end with facebook*, which it only found one: facebook, then it finds all that start with *facebook which includes facebook (the same goes for your other searches)

The API should know what the intersections are between those two searches, but it does not seem to be working.