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Posted to dev@calcite.apache.org by Zhe Hu <il...@163.com> on 2023/06/15 15:18:13 UTC

PR 3258 Review Request

Hi, community.
I’ve submitted a PR for applying two different NULL semantics for CONCAT function, because this function now returns NULL when any of the arguments is NULL, however Postgresql and MSSQL have different behavior(they treat NULL as empty string).
BTW, CONCAT enabled in Oracle(we call it CONCAT2 in Calcite) has been resolved in CALCITE-5745, if anyone needs to refer to.


https://github.com/apache/calcite/pull/3258


Best,
ZheHu

Re: PR 3258 Review Request

Posted by Julian Hyde <jh...@gmail.com>.

Nice work.

(The hardest thing we do, as software engineers, is to make our work easy for others to understand. The fact that several databases have functions called CONCAT, with subtly different behaviors, made this task particularly challenging. You produced a solution that makes the differences really clear.)

I left one comment on the PR but it’s really close.

Julian

> On Jun 15, 2023, at 8:18 AM, Zhe Hu <il...@163.com> wrote:
> 
> Hi, community.
> I’ve submitted a PR for applying two different NULL semantics for CONCAT function, because this function now returns NULL when any of the arguments is NULL, however Postgresql and MSSQL have different behavior(they treat NULL as empty string).
> BTW, CONCAT enabled in Oracle(we call it CONCAT2 in Calcite) has been resolved in CALCITE-5745, if anyone needs to refer to.
> 
> 
> https://github.com/apache/calcite/pull/3258
> 
> 
> Best,
> ZheHu
> 
> 
>