Re: SQL/JSON features for v15 - Mailing list pgsql-hackers

From Amit Langote
Subject Re: SQL/JSON features for v15
Date
Msg-id CA+HiwqFhOswXBiP+edzZ9Z49nVJJA5-ADHqND6+vF9uSiKu-sw@mail.gmail.com
Whole thread Raw
In response to Re: SQL/JSON features for v15  (Amit Langote <amitlangote09@gmail.com>)
List pgsql-hackers
On Tue, Aug 23, 2022 at 4:48 PM Amit Langote <amitlangote09@gmail.com> wrote:
> On Thu, Aug 18, 2022 at 12:46 PM Nikita Glukhov <n.gluhov@postgrespro.ru> wrote:
> > The desciprion of the v7 patches:
> >
> > 0003 Add EEOP_SUBTRANS executor step
> >   v6 + new recursive JIT
> >
> > 0004 Split JsonExpr execution into steps
> >   simply rebase of v6 + used LLMBuildSwitch() in EEOP_JSONEXPR
>
> Will need to spend more time looking at these.

0004 adds the following to initJsonItemCoercions():

+   /* When returning JSON types, no need to initialize coercions */
+   /* XXX domain types on json/jsonb */
+   if (returning->typid == JSONBOID || returning->typid == JSONOID)
+       return NULL;

But maybe it's dead code, because 0001 has this:

+           if (jsexpr->returning->typid != JSONOID &&
+               jsexpr->returning->typid != JSONBOID)
+               jsexpr->coercions =
+                   initJsonItemCoercions(pstate, jsexpr->returning,
+                                         exprType(contextItemExpr));

+               /* We need to handle RETURNING int etc. */

Is this a TODO and what does it mean?

+ *     "JsonCoercion == NULL" means no cast is available.
+ *         "JsonCoercion.expr == NULL" means no coercion is needed.

As said in my previous email, I wonder if these cases are better
handled by adding JSON_COERCION_ERROR and JSON_COERCION_NONE
coercions?

+/* Skip calling ExecEvalJson() on a JsonExpr? */

ExecEvalJsonExpr()

Will look more.

-- 
Thanks, Amit Langote
EDB: http://www.enterprisedb.com



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