beliefer opened a new pull request #29891:
URL: https://github.com/apache/spark/pull/29891
### What changes were proposed in this pull request?
`REGEXP_REPLACE` could replace all substrings of string that match regexp
with replacement string.
But `REGEXP_REPLACE` lost some flexibility. such as: converts camel case
strings to a string containing lower case words separated by an underscore:
AddressLine1 -> address_line_1
If we support the parameter position, we can do like this(e.g. Oracle):
```
CopyWITH strings as (
SELECT 'AddressLine1' s FROM dual union all
SELECT 'ZipCode' s FROM dual union all
SELECT 'Country' s FROM dual
)
SELECT s "STRING",
lower(regexp_replace(s, '([A-Z0-9])', '_\1', 2)) "MODIFIED_STRING"
FROM strings;
STRING MODIFIED_STRING
-------------------- --------------------
AddressLine1 address_line_1
ZipCode zip_code
Country country
```
There are some mainstream database support the syntax.
**Oracle**
https://docs.oracle.com/en/database/oracle/oracle-database/19/sqlrf/REGEXP_REPLACE.html#GUID-EA80A33C-441A-4692-A959-273B5A224490
**Vertica**
https://www.vertica.com/docs/9.2.x/HTML/Content/Authoring/SQLReferenceManual/Functions/RegularExpressions/REGEXP_REPLACE.htm?zoom_highlight=regexp_replace
**Redshift**
https://docs.aws.amazon.com/redshift/latest/dg/REGEXP_REPLACE.html
### Why are the changes needed?
The parameter position for `REGEXP_REPLACE` is very useful.
### Does this PR introduce _any_ user-facing change?
'Yes'.
### How was this patch tested?
Jenkins test.
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