Be more user-friendly about unsupported cases for parallel pg_restore.

If we are unable to do a parallel restore because the input file is stdin
or is otherwise unseekable, we should complain and fail immediately, not
after having done some of the restore.  Complaining once per thread isn't
so cool either, and the messages should be worded to make it clear this is
an unsupported case not some weird race-condition bug.  Per complaint from
Lonni Friedman.

Back-patch to 8.4, where parallel restore was introduced.

diff --git a/src/bin/pg_dump/pg_backup_archiver.c b/src/bin/pg_dump/pg_backup_archiver.c
index 26ee9d96c1f9ba7e63b6822f822071cfdbd5e44e..d4b414fbcfe6f545c6fb3390ed827fb906c5d4a7 100644 (file)
--- a/src/bin/pg_dump/pg_backup_archiver.c
+++ b/src/bin/pg_dump/pg_backup_archiver.c
@@ -3200,6 +3200,12 @@ restore_toc_entries_parallel(ArchiveHandle *AH)
        if (AH->version < K_VERS_1_8)
                die_horribly(AH, modulename, "parallel restore is not supported with archives made by pre-8.0 pg_dump\n");
 
+       /*
+        * It's also not gonna work if we can't reopen the input file, so let's
+        * try that immediately.
+        */
+       (AH->ReopenPtr) (AH);
+
        slots = (ParallelSlot *) calloc(sizeof(ParallelSlot), n_slots);
 
        /* Adjust dependency information */

diff --git a/src/bin/pg_dump/pg_backup_custom.c b/src/bin/pg_dump/pg_backup_custom.c
index 8b7ceb64c7616a8f67877c67a88f3c2b3290124e..cfe4ebba38955b6e11746ff71ab2202db16415f6 100644 (file)
--- a/src/bin/pg_dump/pg_backup_custom.c
+++ b/src/bin/pg_dump/pg_backup_custom.c
@@ -866,10 +866,15 @@ _ReopenArchive(ArchiveHandle *AH)
 
        if (AH->mode == archModeWrite)
                die_horribly(AH, modulename, "can only reopen input archives\n");
+
+       /*
+        * These two cases are user-facing errors since they represent unsupported
+        * (but not invalid) use-cases.  Word the error messages appropriately.
+        */
        if (AH->fSpec == NULL || strcmp(AH->fSpec, "") == 0)
-               die_horribly(AH, modulename, "cannot reopen stdin\n");
+               die_horribly(AH, modulename, "parallel restore from stdin is not supported\n");
        if (!ctx->hasSeek)
-               die_horribly(AH, modulename, "cannot reopen non-seekable file\n");
+               die_horribly(AH, modulename, "parallel restore from non-seekable file is not supported\n");
 
        errno = 0;
        tpos = ftello(AH->FH);