Thread: BUG #2727: pg_restore error on BLOB COMMENTS

The following bug has been logged online:

Bug reference:      2727
Logged by:          Konstantin Pelepelin
Email address:      cat@dtf.ru
PostgreSQL version: 8.1.5
Operating system:   RHEL4
Description:        pg_restore error on BLOB COMMENTS
Details:

I think, it is part of bug #2452 (
http://archives.postgresql.org/pgsql-bugs/2006-05/msg00113.php ), it is not
fixed in 8.1.5

$ pg_restore -v -U postgres -d mydb --disable-triggers -S postgres mydb.tar

...
pg_restore: restoring large object OID 70380132
pg_restore: restored 5116 large objects
pg_restore: restoring BLOB COMMENTS
pg_restore: [tar archiver] could not find header for file 2004.dat in tar
archive
pg_restore: *** aborted because of error


$ pg_restore -l mydb.tar |grep 2004
2004; 0 0 BLOB COMMENTS - BLOB COMMENTS

2004.dat exists in archive and consists of single LF


Workaround:
(pg_restore -l $DBFILE | fgrep -v '0 0 BLOB COMMENTS - BLOB COMMENTS'
>pg_restore_list.txt)
pg_restore -v -U postgres -d $DB --disable-triggers -S postgres -L
pg_restore_list.txt $DBFILE
rm -f pg_restore_list.txt

"Konstantin Pelepelin" <cat@dtf.ru> writes:
> pg_restore: restoring large object OID 70380132
> pg_restore: restored 5116 large objects
> pg_restore: restoring BLOB COMMENTS
> pg_restore: [tar archiver] could not find header for file 2004.dat in tar
> archive
> pg_restore: *** aborted because of error

Hmm ... it looks like blob comments never have worked in tar format,
or not recently anyway.  _LoadBlobs() runs off the end of the archive
file and then there's no mechanism for backing up --- not that that
would work anyway if reading from a pipe.  I'm thinking of fixing it
like this (against HEAD, but the code hasn't changed much lately):


*** src/bin/pg_dump/pg_backup_tar.c.orig    Tue Oct  3 23:16:46 2006
--- src/bin/pg_dump/pg_backup_tar.c    Tue Oct 31 17:27:54 2006
***************
*** 701,706 ****
--- 701,707 ----
      lclContext *ctx = (lclContext *) AH->formatData;
      TAR_MEMBER *th;
      size_t        cnt;
+     bool        foundBlob = false;
      char        buf[4096];

      StartRestoreBlobs(AH);
***************
*** 725,734 ****
                      ahwrite(buf, 1, cnt, AH);
                  }
                  EndRestoreBlob(AH, oid);
              }
          }
-
-         tarClose(AH, th);

          th = tarOpen(AH, NULL, 'r');
      }
--- 726,745 ----
                      ahwrite(buf, 1, cnt, AH);
                  }
                  EndRestoreBlob(AH, oid);
+                 foundBlob = true;
              }
+             tarClose(AH, th);
+         }
+         else
+         {
+             tarClose(AH, th);
+             /*
+              * Once we have found the first blob, stop at the first
+              * non-blob entry (which will be 'blobs.toc').
+              */
+             if (foundBlob)
+                 break;
          }

          th = tarOpen(AH, NULL, 'r');
      }

Thanks for the report!

            regards, tom lane