[jira] [Created] (SPARK-39937) Substring

["Daniel Davies (Jira)" <ji...@apache.org>]

Daniel Davies created SPARK-39937:
-------------------------------------

             Summary: Substring
                 Key: SPARK-39937
                 URL: https://issues.apache.org/jira/browse/SPARK-39937
             Project: Spark
          Issue Type: New Feature
          Components: Spark Core
    Affects Versions: 3.2.2
            Reporter: Daniel Davies


Hello,

We hit a potential limitation of the substring function today that we think might be useful to contribute back to spark, relating to that fact that [substring |https://github.com/apache/spark/blob/775b5ced70c87d6a8709f44eb4a5de48c286a51d/sql/core/src/main/scala/org/apache/spark/sql/functions.scala#L2952] only takes integers for it's pos and len parameters.

Consider the case where you have a list of ID's, and you need to find substrings in these IDs that are dependent on another column (for example, a column expressing the kind of product that the ID represents).

e.g.

{{Table:}}

{{}}

{{}}

ID                  | Type
+-----------+--------+
ABCD12345 |   Water
+-----------+--------+
ABCD12        |  Soda
+-----------+--------+

{{}}

Desired:

ID                  | Type
+-----------+--------+
12345           |   Water
+-----------+--------+
12                  |  Soda
+-----------+--------+

At the moment, you can only extract substrings of fixed position and length- but if IDs have a variable suffix, it may be desirable to run a substring of different lengths based on the 'Type' column.

In this case, it's fairly straightforward to solve with a chain of .when statements; but if there are thousands of types, it may not be as easy.

This seems fairly niche, but I'd be happy to give the implementation a go if this is something that the community would find useful/ has been seen before.



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