Re: SQL:2023 JSON simplified accessor support

> On Aug 29, 2025, at 15:22, Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com> wrote:
>
> +static bool
> +jsonb_check_jsonpath_needed(List *indirection)
> +{
> + ListCell *lc;
> +
> + foreach(lc, indirection)
> + {
> + Node *accessor = lfirst(lc);
> +
> + if (IsA(accessor, String))
> + return true;
>
> Like I mentioned in my previous comment, if we convert String (dot notation) to Indices in rewritten phase, then jsonpath might be no longer needed, and the code logic is much simplified.
>

Taking back this comment. As Alex explained in the other email, dot notation and indices accessor are different.

>
> --- a/src/backend/parser/parse_node.c
> +++ b/src/backend/parser/parse_node.c
> @@ -244,7 +244,7 @@ transformContainerSubscripts(ParseState *pstate,
> Node *containerBase,
> Oid containerType,
> int32 containerTypMod,
> - List *indirection,
> + List **indirection,
> bool isAssignment)
> {
> SubscriptingRef *sbsref;
> @@ -280,7 +280,7 @@ transformContainerSubscripts(ParseState *pstate,
> * element. If any of the items are slice specifiers (lower:upper), then
> * the subscript expression means a container slice operation.
> */
> - foreach(idx, indirection)
> + foreach(idx, *indirection)
> {
> A_Indices *ai = lfirst_node(A_Indices, idx);
>
> Should this foreach be pull up to out of transformContainerSubscripts()? Originally transformContainerSubscripts() runs only once, but now it’s placed in a while loop, and every time this foreach needs to go through the entire indirection list, which are duplicated computation.

After revisiting the code, I think this loop of checking is_slice should be removed here.

It seems only arrsubs cares about this is_slice flag.

hstore_subs can only take a single indirection, so it can do a simple check like:

```
ai = initial_node(A_Indices, *indirection);
If (list_length(*indirection) != 1 || ai->is_slice)
{
ereport(…)
}
```

jsonbsubs doesn’t need to check is_slice flag as well, I will explain that in my next email tougher with my new comments.

So that, “bool isSlace” can be removed from SubscriptTransform, and let every individual subs check is_slice.

Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/