[GitHub] [couchdb] skeyby opened a new issue #3369: $begins Mango Operator

[GitBox <gi...@apache.org>]

skeyby opened a new issue #3369:
URL: https://github.com/apache/couchdb/issues/3369


   
   ## Summary
   
   It would be cool to have a sugar-operator called $begins that is internally implemented as an AND of $gte a $lt to find any value starting with a desired pattern.
   
   ## Desired Behaviour
   
   The usage il something like this: let's suppose we want to find all people with surname starting with "Branca" either for autocompletition purpose or just because the user may have a second surname. Actually one could only do:
   
   ```
   "Surname": {
    $eq: "Branca" 
   }
   ```
   
   That wouldn't find either "Brancatelli" nor "Branca SecondSurname"
   
   The only solution would be to:
   
   ```
   "Surname": { 
     $regex: "Branca"
   }
   ```
   
   That is unindexed.
   
   
   ## Possible Solution
   
   
   As in summary a solution could be to implement a sugar-operator called $begins that internally gets mapped to an AND-combination of $gte and $lt with an upper character as an upper bound. So, calling:
   
   ```
   "Surname": {
    $begins: "Branca" 
   }
   ```
   
   would be translated in
   
   ```
   $and: [
    { "Surname": { $gte: "Branca" } },
    { "Surname": { $lt: "Branca\ufff0" } }
   ]
   ```
   
   That would use the index as expected.
   
   


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