[Couchdb Wiki] Update of "View collation" by BrianCandler

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The following page has been changed by BrianCandler:
http://wiki.apache.org/couchdb/View_collation

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+ Comparison of strings is done using [http://site.icu-project.org/ ICU] which implements the [http://www.unicode.org/unicode/reports/tr10/ Unicode Collation Algorithm]. This can give surprising results if you were expecting ASCII collation. Note that:
+ 
+ * All symbols sort before numbers and letters (even the "high" symbols like tilde, 0x7e)
+ * Differing sequences of letters are compared without regard to case, so a < aa but also A < aa
+ * Identical sequences of letters are compared with regard to case, with lowercase *before* uppercase, so a < A
+ 
+ You can demonstrate the collation sequence like this:
+ 
+ {{{
+ require 'rubygems'
+ require 'restclient'
+ require 'json'
+ 
+ DB="http://127.0.0.1:5984/collator"
+ 
+ RestClient.delete DB rescue nil
+ RestClient.put "#{DB}",""
+ 
+ (32..126).each do |c|
+   RestClient.put "#{DB}/#{c.to_s(16)}", {"x"=>c.chr}.to_json
+ end
+ 
+ RestClient.put "#{DB}/_design/test", <<EOS
+ {
+   "views":{
+     "one":{
+       "map":"function (doc) { emit(doc.x,null); }"
+     }
+   }
+ }
+ EOS
+ 
+ puts RestClient.get("#{DB}/_design/test/_view/one")
+ }}}
+ 
+ Results:
+ {{{
+ {"total_rows":95,"offset":0,"rows":[
+ {"id":"20","key":" ","value":null},
+ {"id":"60","key":"`","value":null},
+ {"id":"5e","key":"^","value":null},
+ {"id":"5f","key":"_","value":null},
+ {"id":"2d","key":"-","value":null},
+ {"id":"2c","key":",","value":null},
+ {"id":"3b","key":";","value":null},
+ {"id":"3a","key":":","value":null},
+ {"id":"21","key":"!","value":null},
+ {"id":"3f","key":"?","value":null},
+ {"id":"2e","key":".","value":null},
+ {"id":"27","key":"'","value":null},
+ {"id":"22","key":"\"","value":null},
+ {"id":"28","key":"(","value":null},
+ {"id":"29","key":")","value":null},
+ {"id":"5b","key":"[","value":null},
+ {"id":"5d","key":"]","value":null},
+ {"id":"7b","key":"{","value":null},
+ {"id":"7d","key":"}","value":null},
+ {"id":"40","key":"@","value":null},
+ {"id":"2a","key":"*","value":null},
+ {"id":"2f","key":"/","value":null},
+ {"id":"5c","key":"\\","value":null},
+ {"id":"26","key":"&","value":null},
+ {"id":"23","key":"#","value":null},
+ {"id":"25","key":"%","value":null},
+ {"id":"2b","key":"+","value":null},
+ {"id":"3c","key":"<","value":null},
+ {"id":"3d","key":"=","value":null},
+ {"id":"3e","key":">","value":null},
+ {"id":"7c","key":"|","value":null},
+ {"id":"7e","key":"~","value":null},
+ {"id":"24","key":"$","value":null},
+ {"id":"30","key":"0","value":null},
+ {"id":"31","key":"1","value":null},
+ {"id":"32","key":"2","value":null},
+ {"id":"33","key":"3","value":null},
+ {"id":"34","key":"4","value":null},
+ {"id":"35","key":"5","value":null},
+ {"id":"36","key":"6","value":null},
+ {"id":"37","key":"7","value":null},
+ {"id":"38","key":"8","value":null},
+ {"id":"39","key":"9","value":null},
+ {"id":"61","key":"a","value":null},
+ {"id":"41","key":"A","value":null},
+ {"id":"62","key":"b","value":null},
+ {"id":"42","key":"B","value":null},
+ {"id":"63","key":"c","value":null},
+ {"id":"43","key":"C","value":null},
+ {"id":"64","key":"d","value":null},
+ {"id":"44","key":"D","value":null},
+ {"id":"65","key":"e","value":null},
+ {"id":"45","key":"E","value":null},
+ {"id":"66","key":"f","value":null},
+ {"id":"46","key":"F","value":null},
+ {"id":"67","key":"g","value":null},
+ {"id":"47","key":"G","value":null},
+ {"id":"68","key":"h","value":null},
+ {"id":"48","key":"H","value":null},
+ {"id":"69","key":"i","value":null},
+ {"id":"49","key":"I","value":null},
+ {"id":"6a","key":"j","value":null},
+ {"id":"4a","key":"J","value":null},
+ {"id":"6b","key":"k","value":null},
+ {"id":"4b","key":"K","value":null},
+ {"id":"6c","key":"l","value":null},
+ {"id":"4c","key":"L","value":null},
+ {"id":"6d","key":"m","value":null},
+ {"id":"4d","key":"M","value":null},
+ {"id":"6e","key":"n","value":null},
+ {"id":"4e","key":"N","value":null},
+ {"id":"6f","key":"o","value":null},
+ {"id":"4f","key":"O","value":null},
+ {"id":"70","key":"p","value":null},
+ {"id":"50","key":"P","value":null},
+ {"id":"71","key":"q","value":null},
+ {"id":"51","key":"Q","value":null},
+ {"id":"72","key":"r","value":null},
+ {"id":"52","key":"R","value":null},
+ {"id":"73","key":"s","value":null},
+ {"id":"53","key":"S","value":null},
+ {"id":"74","key":"t","value":null},
+ {"id":"54","key":"T","value":null},
+ {"id":"75","key":"u","value":null},
+ {"id":"55","key":"U","value":null},
+ {"id":"76","key":"v","value":null},
+ {"id":"56","key":"V","value":null},
+ {"id":"77","key":"w","value":null},
+ {"id":"57","key":"W","value":null},
+ {"id":"78","key":"x","value":null},
+ {"id":"58","key":"X","value":null},
+ {"id":"79","key":"y","value":null},
+ {"id":"59","key":"Y","value":null},
+ {"id":"7a","key":"z","value":null},
+ {"id":"5a","key":"Z","value":null}
+ ]}
+ }}}
+