Hi,
On 29/11/24 04:28, Nazir Bilal Yavuz wrote:
- for (; blkno < nblocks; blkno++)
+ p.last_exclusive = nblocks;
+
+ while (BufferIsValid(buf = read_stream_next_buffer(stream, NULL)))
{
CHECK_FOR_INTERRUPTS();
- pagefn(&stat, rel, blkno, bstrategy);
+ pagefn(&stat, rel, buf);
}
+
+ Assert(read_stream_next_buffer(stream, NULL) == InvalidBuffer);
With this change we assume that if stream returns an invalid buffer
that means stream must be finished. We don't check if the stream
didn't finish but somehow read an invalid buffer. In the upstream
version, if we read an invalid buffer then postgres server will fail.
But in the patched version, the server will continue to run because it
will think that stream has reached to end. This could be happening for
other streaming read users; for example at least the
read_stream_next_buffer() calls in the collect_corrupt_items()
function face the same issue.
Just for reference; On pg_prewarm() for example this loop is
implemented as:
for (block = first_block; block <= last_block; ++block)
{
Buffer buf;
...
buf = read_stream_next_buffer(stream, NULL);
...
}
Assert(read_stream_next_buffer(stream, NULL) == InvalidBuffer);
Would this approach make sense on these cases? (this patch and on
collect_corrupt_items)
--
Matheus Alcantara
