Re: [PATCH] Fix null pointer dereference in PG19

On Tue, Apr 21, 2026 at 11:24 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
> * contain_volatile_functions_after_planning is utterly wrong
> to apply here. That should happen somewhere in the planner,
> where it'd be cheaper as well as not premature.
>

typedef struct ForPortionOfExpr
{
NodeTag type;
Var *rangeVar; /* Range column */
char *range_name; /* Range name */
Node *targetFrom; /* FOR PORTION OF FROM bound, if given */
Node *targetTo; /* FOR PORTION OF TO bound, if given */
Node *targetRange; /* FOR PORTION OF bounds as a
range/multirange */
Oid rangeType; /* (base)type of targetRange */
bool isDomain; /* Is rangeVar a domain? */
Node *overlapsExpr; /* range && targetRange */
List *rangeTargetList; /* List of TargetEntrys to set the time
* column(s) */
Oid withoutPortionProc; /* SRF proc for old_range -
target_range */
ParseLoc location; /* token location, or -1 if unknown */
ParseLoc targetLocation; /* token location, or -1 if unknown */
} ForPortionOfExpr;

targetFrom and targetTo is only for deparsing purpose, skip
eval_const_expressions should be fine.

RewriteQuery, we have:
``````
AddQual(parsetree, parsetree->forPortionOf->overlapsExpr);
/* Update FOR PORTION OF column(s) automatically. */
foreach(tl, parsetree->forPortionOf->rangeTargetList)
{
TargetEntry *tle = (TargetEntry *) lfirst(tl);
parsetree->targetList = lappend(parsetree->targetList, tle);
}
``````
rangeTargetList and overlapsExpr will go through eval_const_expressions.
Only ForPortionOfExpr->targetRange really needs to be dealt with.

In ExecInitModifyTable, we already did
ExecPrepareExpr(forPortionOf->targetRange),
which will do eval_const_expressions(forPortionOf->targetRange).

moving contain_volatile_functions_after_planning to
ExecInitModifyTable should be fine.

In ExecInitModifyTable, we can't just
```
exprState = ExecPrepareExpr((Expr *) forPortionOf->targetRange, estate);
if (contain_volatile_functions_after_planning(exprState->expr)
```

Because of the comments below in execnodes.h:

typedef struct ExprState
/* original expression tree, for debugging only */
Expr *expr;

While at it, add errcode to the surrounding code.

--
jian
https://www.enterprisedb.com/