Re: [PATCH] Fix ouside scope t_ctid (ItemPointerData)

> On May 14, 2020, at 11:34 AM, Ranier Vilela <ranier(dot)vf(at)gmail(dot)com> wrote:
>
> htup->t_ctid = target_tid;
> htup->t_ctid = newtid;
> Both target_tid and newtid are local variable, whe loss scope, memory is garbage.

Ok, thanks for the concrete example of what is bothering you.

In htup_details, I see that struct HeapTupleHeaderData has a field named t_ctid of type struct ItemPointerData. I also see in heapam that target_tid is of type ItemPointerData. The

htup->t_ctid = target_tid

copies the contents of target_tid. By the time target_tid goes out of scope, the contents are already copied. I would share your concern if t_ctid were of type ItemPointer (aka ItemPointerData *) and the code said

htup->t_ctid = &target_tid

but it doesn't say that, so I don't see the issue.

Also in heapam, I see that newtid is likewise of type ItemPointerData, so the same logic applies. By the time newtid goes out of scope, its contents have already been copied into t_ctid, so there is no problem.

But maybe you know all that and are just complaining that the name "ItemPointerData" sounds like a pointer rather than a struct? I'm still unclear whether you believe this is a bug, or whether you just don't like the naming that is used.

—
Mark Dilger
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