Re: backup manifests - Mailing list pgsql-hackers

On Sat, Sep 21, 2019 at 12:25 AM Robert Haas <robertmhaas@gmail.com> wrote:
>
Some comments:

Manifest file will be in plain text format even if compression is
specified, should we compress it?
May be this is intended, just raised the point to make sure that it is intended.
+static void
+ReceiveBackupManifestChunk(size_t r, char *copybuf, void *callback_data)
+{
+ WriteManifestState *state = callback_data;
+
+ if (fwrite(copybuf, r, 1, state->file) != 1)
+ {
+ pg_log_error("could not write to file \"%s\": %m", state->filename);
+ exit(1);
+ }
+}

WALfile.done file gets added but wal file information is not included
in the manifest file, should we include WAL file also?
@@ -599,16 +618,20 @@ perform_base_backup(basebackup_options *opt)
  (errcode_for_file_access(),
  errmsg("could not stat file \"%s\": %m", pathbuf)));

- sendFile(pathbuf, pathbuf, &statbuf, false, InvalidOid);
+ sendFile(pathbuf, pathbuf, &statbuf, false, InvalidOid, manifest,
+ NULL);

  /* unconditionally mark file as archived */
  StatusFilePath(pathbuf, fname, ".done");
- sendFileWithContent(pathbuf, "");
+ sendFileWithContent(pathbuf, "", manifest);

Should we add an option to make manifest generation configurable to
reduce overhead during backup?

Manifest file does not include directory information, should we include it?

There is one warning:
In file included from ../../../src/include/fe_utils/string_utils.h:20:0,
                 from pg_basebackup.c:34:
pg_basebackup.c: In function ‘ReceiveTarFile’:
../../../src/interfaces/libpq/pqexpbuffer.h:60:9: warning: the
comparison will always evaluate as ‘false’ for the address of ‘buf’
will never be NULL [-Waddress]
  ((str) == NULL || (str)->maxlen == 0)
         ^
pg_basebackup.c:1203:7: note: in expansion of macro ‘PQExpBufferBroken’
   if (PQExpBufferBroken(&buf))

pg_gmtime can fail in case of malloc failure:
+ /*
+ * Convert time to a string. Since it's not clear what time zone to use
+ * and since time zone definitions can change, possibly causing confusion,
+ * use GMT always.
+ */
+ pg_strftime(timebuf, sizeof(timebuf), "%Y-%m-%d %H:%M:%S %Z",
+ pg_gmtime(&mtime));