Re: SQL/JSON: JSON_TABLE

Thank you for review.

Attached 45th version of the patches. "SQL/JSON functions" patch corresponds to
v52 patch set posted in the separate thread.

On 27.12.2020 01:16, Zhihong Yu wrote:
> For new files introduced in the patches:
>
> + * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
>
> 2021 is a few days ahead. It would be good to update the year range.

Fixed.

> For transformJsonTableColumn:
>
> +   jfexpr->op =
> +       jtc->coltype == JTC_REGULAR ? IS_JSON_VALUE :
> +       jtc->coltype == JTC_EXISTS ? IS_JSON_EXISTS : IS_JSON_QUERY;
>
> Should IS_JSON_EXISTS be mentioned in the comment preceding the method ?

Added mention of EXISTS PATH column to the comment.

> For JsonTableDestroyOpaque():
>
> +   state->opaque = NULL;
>
> Should the memory pointed to by opaque be freed ?

I think it's not necessary, because FunctionScan, caller of
JsonTableDestroyOpaque(), will free it and also all opaque's fields using
MemoryContextReset().

>
> +   l2 = list_head(tf->coltypes);
> +   l3 = list_head(tf->coltypmods);
> +   l4 = list_head(tf->colvalexprs);
>
> Maybe the ListCell pointer variables can be named corresponding to the
> lists they iterate so that the code is easier to understand.

Variable were renamed, also foreach() loop was refactored using forfour() macro.

>
> +typedef enum JsonTablePlanJoinType
> +{
> +   JSTP_INNER = 0x01,
> +   JSTP_OUTER = 0x02,
> +   JSTP_CROSS = 0x04,
>
> Since plan type enum starts with JSTP_, I think the plan join type
> should start with JSTPJ_ or JSTJ_. Otherwise the following would be a
> bit hard to read:
>
> +   else if (plan->plan_type == JSTP_JOINED)
> +   {
> +       if (plan->join_type == JSTP_INNER ||
> +           plan->join_type == JSTP_OUTER)
>
> since different fields are checked in the two if statements but the
> prefixes don't convey that.

Enumeration members were renames using prefix JSTPJ_.

> +      Even though the path names are not incuded into the
> <literal>PLAN DEFAULT</literal>
>
> Typo: incuded -> included

Fixed.

> +   int         nchilds = 0;
>
> nchilds -> nchildren

Fixed.

>
> +#if 0 /* XXX it' unclear from the standard whether root path name is
> mandatory or not */
> +   if (plan && plan->plan_type != JSTP_DEFAULT && !rootPathName)
>
> Do you plan to drop the if block ?

If it becomes clear, I will drop it.

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