Add REGEXP_EXTRACT built-in function

[hjafarpour]

This built-in function will help extracting a string using the pattern.

[big-andy-coates]

Hi @hjafarpour - given that these are internal functions, not user-defined, it might be clearer to give them another name... KDFs! (Well, that's one option anyway).

[apurvam]

How is this different from #881 ? cc @rmoff

[rmoff]

I'd +1 not calling it a UDF

From my point of view both INSTR and REGEXP_EXTRACT are useful. The former is simpler and more accessible (and more familiar to more SQL users). The latter is more powerful but requires knowledge of regex, and for simple stuff is thus overkill.

[hjafarpour]

@big-andy-coates I changed it to build-in functions :)

[bluemonk3y]

Built-in would be the presumed standard. I.e Cassandra etc

On 13 Mar 2018 18:49, "Hojjat Jafarpour" notifications@github.com wrote:

We can call them build in functions :)

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[blueedgenick]

+1 for a regexp_extract function

[stevenpyzhang]

What exactly is the behavior we want for this function? I've been looking through other example of REGEXP_EXTRACT and there's slight variance in all their behaviors.

https://docs.data.world/documentation/sql/reference/functions/regexp_extract.html https://www.ibm.com/support/knowledgecenter/SS5FPD_1.0.0/com.ibm.ips.doc/postgresql/sqltk/r_sqlext_regexp_extract.html

cc @confluentinc/ksql

[blueedgenick]

As usual, the Presto team has a well thought out approach to this (family of) function: https://prestodb.io/docs/current/functions/regexp.html. I'd look there for inspiration.

On Thu, Mar 5, 2020, 1:02 PM Steven Zhang notifications@github.com wrote:

What exactly is the behavior we want for this function? I've been looking through other example of REGEXP_EXTRACT and there's slight variance in all their behaviors.

https://docs.data.world/documentation/sql/reference/functions/regexp_extract.html

https://www.ibm.com/support/knowledgecenter/SS5FPD_1.0.0/com.ibm.ips.doc/postgresql/sqltk/r_sqlext_regexp_extract.html

cc @confluentinc/ksql https://github.com/orgs/confluentinc/teams/ksql

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[vcrfxia]

This was implemented in https://github.com/confluentinc/ksql/pull/4728 and will be released with ksqlDB 0.8.0