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SQL/JSON: Fix some oversights in commit b6e1157e7

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The decision in b6e1157e7 to ignore raw_expr when evaluating a
JsonValueExpr was incorrect.  While its value is not ultimately
used (since formatted_expr's value is), failing to initialize it
can lead to problems, for instance,  when the expression tree in
raw_expr contains Aggref nodes, which must be initialized to
ensure the parent Agg node works correctly.

Also, optimize eval_const_expressions_mutator()'s handling of
JsonValueExpr a bit.  Currently, when formatted_expr cannot be folded
into a constant, we end up processing it twice -- once directly in
eval_const_expressions_mutator() and again recursively via
ece_generic_processing().  This recursive processing is required to
handle raw_expr. To avoid the redundant processing of formatted_expr,
we now  process raw_expr directly in eval_const_expressions_mutator().

Finally, update the comment of JsonValueExpr to describe the roles of
raw_expr and formatted_expr more clearly.

Bug: #18657
Reported-by: Alexander Lakhin <exclusion@gmail.com>
Diagnosed-by: Fabio R. Sluzala <fabio3rs@gmail.com>
Diagnosed-by: Tender Wang <tndrwang@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/18657-1b90ccce2b16bdb8@postgresql.org
Backpatch-through: 16
This commit is contained in:
Amit Langote
2024-10-20 12:20:55 +09:00
parent 52475b4d30
commit 11c87216d1
5 changed files with 92 additions and 11 deletions
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24
src/backend/optimizer/util/clauses.c
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@ -2915,13 +2915,25 @@ eval_const_expressions_mutator(Node *node,
case T_JsonValueExpr:
{
JsonValueExpr *jve = (JsonValueExpr *) node;
Node *formatted;
Node *raw_expr = (Node *) jve->raw_expr;
Node *formatted_expr = (Node *) jve->formatted_expr;
formatted = eval_const_expressions_mutator((Node *) jve->formatted_expr,
context);
if (formatted && IsA(formatted, Const))
return formatted;
break;
/*
* If we can fold formatted_expr to a constant, we can elide
* the JsonValueExpr altogether. Otherwise we must process
* raw_expr too. But JsonFormat is a flat node and requires
* no simplification, only copying.
*/
formatted_expr = eval_const_expressions_mutator(formatted_expr,
context);
if (formatted_expr && IsA(formatted_expr, Const))
return formatted_expr;
raw_expr = eval_const_expressions_mutator(raw_expr, context);
return (Node *) makeJsonValueExpr((Expr *) raw_expr,
(Expr *) formatted_expr,
copyObject(jve->format));
}
case T_SubPlan: