Add regexp_extract func

[SKY-ALIN]

Which issue does this PR close?

Closes #14280.

Rationale for this change

Adding more functions

What changes are included in this PR?

The implementation of regexp_extract based on Spark regexp_extract

Are these changes tested?

Yes

Are there any user-facing changes?

No

[Omega359]

Thanks for your contribution! I've left some comments for your review.

[alamb]

FYI @Omega359 noted this is quite similar to

• feat: Add regexp_substr function #14323

[rluvaton]

FYI Spark regex is not the same as Rust regex and can have different results

[Omega359]

This is looking good.

• I may have missed it but I don't see tests for out of bounds indexes (negative #'s, index larger than match group count).
• The docs do not say whether the index is 0-indexed or 1-indexed.
• I would love to see a benchmark for this but that absolutely could be added as a followup PR
• The returning of Utf8View should be corrected - either just return Utf8/LargeUtf8 or fix the return to actually return utf8view if input is utf8view

My primary concern is there are two PR's for essentially the same functionality. I am not in a position to decide which should be included.

[rluvaton]

Can you implement return_type_from_args with marking nullable true only if the any of the input types are nullable (similiar to this #14841)

[Omega359]

@SKY-ALIN - are you able to look into the above review comments?

[Omega359]

I'll take a look at this later today @SKY-ALIN

[Omega359]

I spent some time today looking at this PR. Here are my thoughts:

• This udf closely mirrors the duckdb functionality but it does not mirror the typical regex substring functionality found in postgres, mysql, sql server nor oracle
• I do not think that datafusion should have both regexp_extract and regexp_substring functionality as the general consensus has been to try and mirror postgresql with respect to functionality if possible. Thus, if I was to choose to include this type of function it would be the regexp_substr, not regexp_extract. That is not to say that there isn't merit with regexp_extract but it may be best to have it in a repo such as datafusion-functions-extra or similar.

As a note the regexp_substr PR (#14323) is about to expire and the author looks to have submitted it and abandoned it. I think there is a number of ideas that you've implemented in this PR that could be incorporated into a new PR perhaps based on the above mentioned PR?

Just a thought if you are interested - I myself really do appreciate the work you've put into this PR ❤️