Re: pg_receivewal fail to streams when the partial file to write is not fully initialized present in the wal receiver directory

On Sun, Jan 02, 2022 at 09:27:43PM -0800, SATYANARAYANA NARLAPURAM wrote:
> I noticed that pg_receivewal fails to stream when the partial file to write
> is not fully initialized and fails with the error message something like
> below. This requires an extra step of deleting the partial file that is not
> fully initialized before starting the pg_receivewal. Attaching a simple
> patch that creates a temp file, fully initialize it and rename the file to
> the desired wal segment name.

Are you referring to the pre-padding when creating a new partial
segment, aka when we write chunks of XLOG_BLCKSZ full of zeros until
the file is fully created? What kind of error did you see? I guess
that a write() with ENOSPC would be more likely, but you got a
different problem? I don't disagree with improving such cases, but we
should not do things so as there is a risk of leaving behind an
infinite set of segments in case of repeated errors, and partial
segments are already a kind of temporary file.

- if (dir_data->sync)
+ if (shouldcreatetempfile)
+ {
+ if (durable_rename(tmpsuffixpath, targetpath) != 0)
+ {
+ close(fd);
+ unlink(tmpsuffixpath);
+ return NULL;
+ }
+ }

durable_rename() does a set of fsync()'s, but --no-sync should not
flush any data.
--
Michael