Re: SQL/JSON: JSON_TABLE

Attached 40th version of the patches.

On 19.10.2019 18:31, Pavel Stehule wrote:
> This patch is still pretty big - it is about 6000 lines (without any
> documentation). I checked the standard - and this patch try to implement
>
> JSON_TABLE as part of T821
> Plan clause T824
> Plan default clause T838.
>
> Unfortunately for last two features there are few documentation other
> than standard, and probably other databases doesn't implement these
> features (I didn't find it in Oracle, MySQL, MSSQL and DB2) . Can be
> this patch divided by these features? I hope so separate review and
> commit can increase a chance to merge this code (or the most
> significant part) in this release.
>
> It is pretty hard to do any deeper review without documentation and
> without other information sources.
>
> What do you think?

I think it is a good idea. So I have split JSON_TABLE patch into three
patches, each SQL feature. This really helped to reduce the size of the
main patch by about 40%.

On 30.09.2019 19:09, Pavel Stehule wrote:
> Regress tests fails on my comp - intel 64bit Linux, gcc 9.2.1
>
Unfortunately, this is still not reproducible on my computer with 64bit
Linux and gcc 9.2.1.

> Comments:
>
> * +<->/* Only XMLTABLE and JSON_TABLE are supported currently */
>
> this comment has not sense more. Can be removed. Probably long time
> there will not be new format like XML or JSON
Fixed.

> * there are new 600 lines to parse_clause.c, maybe this code can be
> placed in new file parse_jsontable.c ? parse_clause.c is pretty long
> already (json_table has very complex syntax)
Ok, the code was moved to parse_jsontable.c.

> *
> +<->if (list_length(ci->passing.values) > 0)
> +<->{
> +<-><-->ListCell   *exprlc;
> +<-><-->ListCell   *namelc;
> +
>
> It's uncommon usage of list_length function. More common is just "if
> (ci->passing.values) {}". Is there any reason for list_length?
>
Fixed.

> * I tested some examples that I found on net. It works very well.
> Minor issues are white chars for json type. Probably json_table should
> to trim returned values, because after cutting from document, original
> white chars lost sense. It is not a problem jsonb type, that reduce
> white chars on input.
>
> I did only simple tests and I didn't find any other issues than white
> chars problems for json type. I'll continue in some deeper tests.
> Please, prepare documentation. Without documentation there is not
> clean what features are supported. I have to do blind testing.
>
I have added some documentation to the patches which has simply been
copied from [1], but It still needs some work.

[1]
https://www.postgresql.org/message-id/732208d3-56c3-25a4-8f08-3be1d54ad51b%40postgrespro.ru

--
Nikita Glukhov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company