[GitHub] sqoop pull request: [SQOOP-2906] Optimize toAvroIdentifier

[stanleyxu2005 <gi...@git.apache.org>]

Github user stanleyxu2005 commented on a diff in the pull request:

    https://github.com/apache/sqoop/pull/18#discussion_r59360059
  
    --- Diff: src/java/org/apache/sqoop/avro/AvroUtil.java ---
    @@ -114,11 +114,20 @@ public static String toAvroColumn(String column) {
        * Format candidate to avro specifics
        */
       public static String toAvroIdentifier(String candidate) {
    -    String formattedCandidate = candidate.replaceAll("\\W+", "_");
    -    if (formattedCandidate.substring(0,1).matches("[a-zA-Z_]")) {
    -      return formattedCandidate;
    +    char[] data = candidate.toCharArray();
    +    int stringIndex = 0;
    +
    +    for (char c:data) {
    +      if (Character.isLetterOrDigit(c) || c == '_') {
    +        data[stringIndex++] = c;
    +      }
    +    }
    +
    +    char initial = data[0];
    +    if (Character.isLetter(initial) || initial == '_') {
    +      return new String(data, 0, stringIndex);
    --- End diff --
    
    Your code will first create a char array and then eventually update char in the array. As result you will create another copy as a new String. Have you thought about using a `StringBuilder` directly?
    ```
      final StringBuilder sb = new StringBuilder();
      for (char c : candidate) {
        if (Character.isLetterOrDigit(c) || c == '_') {
          sb.append(c);
        }
      }
      ...
        return sb.toString();
    ```


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