Bug in pg_get_aios()

On Mar 23, 2026, at 14:23, cca5507 <cca5507@qq.com> wrote:

Hi,

If I understand correctly, we want to set nulls[0] to true if owner_pid equals to 0:

```
diff --git a/src/backend/storage/aio/aio_funcs.c b/src/backend/storage/aio/aio_funcs.c
index 8997c762062..bcdd82318f7 100644
--- a/src/backend/storage/aio/aio_funcs.c
+++ b/src/backend/storage/aio/aio_funcs.c
@@ -149,7 +149,7 @@ retry:
if (owner_pid != 0)
values[0] = Int32GetDatum(owner_pid);
else
-                       nulls[0] = false;
+                       nulls[0] = true;

/* column: IO's id */
values[1] = Int32GetDatum(ioh_id);
```

--
Regards,
ChangAo Chen

Indeed an obvious bug.

If we looking downwards, there is a correct usage:
```
/* column: raw result (i.e. some form of syscall return value) */
if (start_state == PGAIO_HS_COMPLETED_IO
|| start_state == PGAIO_HS_COMPLETED_SHARED
|| start_state == PGAIO_HS_COMPLETED_LOCAL)
values[9] = Int32GetDatum(ioh_copy.result);
else
nulls[9] = true;
```

Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/

On Mon, Mar 23, 2026 at 02:30:28PM +0800, Chao Li wrote:

On Mar 23, 2026, at 14:23, cca5507 <cca5507@qq.com> wrote:
If I understand correctly, we want to set nulls[0] to true if owner_pid equals to 0:

Indeed an obvious bug.

Or the intention of the code could have been to allow a PID value of 0
to be exposed, but I don't really buy it. Will fix, thanks for the
report.
--
Michael

Hi,

On March 23, 2026 4:44:21 AM EDT, Michael Paquier <michael@paquier.xyz> wrote:

On Mon, Mar 23, 2026 at 02:30:28PM +0800, Chao Li wrote:

On Mar 23, 2026, at 14:23, cca5507 <cca5507@qq.com> wrote:
If I understand correctly, we want to set nulls[0] to true if owner_pid equals to 0:

Indeed an obvious bug.

Or the intention of the code could have been to allow a PID value of 0
to be exposed, but I don't really buy it.

That certainly wasn't the intent :).

I suspect this is unreachable, we wait for ios before exiting, but of course that doesn't excuse broken code.

Will fix, thanks for the report.

Thanks!

Andres

--
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