Re: speedup COPY TO for partitioned table.

On Oct 10, 2025, at 10:54, jian he <jian.universality@gmail.com> wrote:

5
```
+static void
+CopyRelTo(CopyToState cstate, Relation rel, Relation root_rel,
+  uint64 *processed)
```

Instead of using a pointer to pass out processed count, I think it’s better to return the process count. I understand the current implementation allows continuous increment while calling this function in a loop. However, it’s a bit error-prone, a caller must make sure “processed” is well initialized. With returning a unit64, the caller’s code is still simple:

```
processed += CopyRelTo(cstate, …);
```

pgstat_progress_update_param was within CopyRelTo.
so we have to pass (uint64 *processed) to CopyRelTo.
Am I missing something?


Make sense. I didn’t notice postage_progress_update_param. So, “processed” is both input and output. In that case, I think the comment for parameter “processed” should be enhanced, for example:

if your function is:

static processed CopyRelationTo(CopyToState cstate, Relation rel,
Relation root_rel, uint64 *processed);

where function return value is also passed as function argument,
I think it will lead to more confusion.