The previous design for this had copyFile(), linkFile(), and
rewriteVisibilityMap() returning strerror strings, with the caller
producing one-size-fits-all error messages based on that. This made it
impossible to produce messages that described the failures with any degree
of precision, especially not short-read problems since those don't set
errno at all.
Since pg_upgrade has no intention of continuing after any error in this
area, let's fix this by just letting these functions call pg_fatal() for
themselves, making it easy for each point of failure to have a suitable
error message. Taking this approach also allows dropping cleanup code
that was unnecessary and was often rather sloppy about preserving errno.
To not lose relevant info that was reported before, pass in the schema name
and table name of the current table so that they can be included in the
error reports.
An additional problem was the use of getErrorText(), which was flat out
wrong for all but a couple of call sites, because it unconditionally did
"_dosmaperr(GetLastError())" on Windows. That's only appropriate when
reporting an error from a Windows-native API, which only a couple of
the callers were actually doing. Thus, even the reported strerror string
would be unrelated to the actual failure in many cases on Windows.
To fix, get rid of getErrorText() altogether, and just have call sites
do strerror(errno) instead, since that's the way all the rest of our
frontend programs do it. Add back the _dosmaperr() calls in the two
places where that's actually appropriate.
In passing, make assorted messages hew more closely to project style
guidelines, notably by removing initial capitals in not-complete-sentence
primary error messages. (I didn't make any effort to clean up places
I didn't have another reason to touch, though.)
Per discussion of a report from Thomas Kellerer. Back-patch to 9.6,
but no further; given the relative infrequency of reports of problems
here, it's not clear it's worth adapting the patch to older branches.
Patch by me, but with credit to Alvaro Herrera for spotting the issue
with getErrorText's misuse of _dosmaperr().
Discussion: <nsjrbh$8li$1@blaine.gmane.org>
For historical reasons, copyFile and rewriteVisibilityMap took a force
argument which was always passed as true, meaning that any existing
file should be overwritten. However, it seems much safer to instead
fail if a file we need to write already exists.
While we're at it, remove the "force" argument altogether, since it was
never passed as anything other than true (and now we would never pass
it as anything other than false, if we kept it).
Noted by Andres Freund during post-commit review of the patch that added
rewriteVisibilityMap, commit 7087166a88,
but this also changes the behavior when copying files without rewriting
them.
Patch by Masahiko Sawada.
This patch essentially reverts commit 4c6780fd17, in favor of a much
simpler solution for the case where the new cluster would choose to create
a TOAST table but the old cluster doesn't have one: just don't create a
TOAST table.
The existing code failed in at least two different ways if the situation
arose: (1) ALTER TABLE RESET didn't grab an exclusive lock, so that the
lock sanity check in create_toast_table failed; (2) pg_upgrade did not
provide a pg_type OID for the new toast table, so that the crosscheck in
TypeCreate failed. While both these problems were introduced by later
patches, they show that the hack being used to cause TOAST table creation
is overwhelmingly fragile (and untested). I also note that before the
TypeCreate crosscheck was added, the code would have resulted in assigning
an indeterminate pg_type OID to the toast table, possibly causing a later
OID conflict in that catalog; so that it didn't really work even when
committed.
If we simply don't create a TOAST table, there will only be a problem if
the code tries to store a tuple that's wider than a page, and field
compression isn't sufficient to get it under a page. Given that the TOAST
creation threshold is intended to be about a quarter of a page, it's very
hard to believe that cross-version differences in the do-we-need-a-toast-
table heuristic could result in an observable problem. So let's just
follow the old version's conclusion about whether a TOAST table is needed.
(If we ever do change needs_toast_table() so much that this conclusion
doesn't apply, we can devise a solution at that time, and hopefully do
it in a less klugy way than 4c6780fd17 did.)
Back-patch to 9.3, like the previous patch.
Discussion: <8110.1462291671@sss.pgh.pa.us>
Ordinarily, pg_upgrade shouldn't have any difficulty in matching up all
the relations it sees in the old and new databases. If it does, however,
it just goes belly-up with a pretty unhelpful error message. That seemed
fine as long as we expected the case never to occur in the wild, but
Alvaro reported that it had been seen in a database whose pg_largeobject
table had somehow acquired a TOAST table. That doesn't quite seem like
a case that pg_upgrade actually needs to handle, but it would be good if
the report were more diagnosable. Hence, extend the logic to print out
as much information as we can about the mismatch(es) before we quit.
In passing, improve the readability of get_rel_infos()'s data collection
query, which had suffered seriously from lets-not-bother-to-update-comments
syndrome, and generally was unnecessarily disrespectful to readers.
It could be argued that this is a bug fix, but given that we have so few
reports, I don't feel a need to back-patch; at least not before this has
baked awhile in HEAD.
Commit a892234f83 added a second bit per
page to the visibility map, but pg_upgrade has been unaware of it up
until now. Therefore, a pg_upgrade from an earlier major release of
PostgreSQL to any commit preceding this one and following the one
mentioned above would result in invalid visibility map contents on the
new cluster, very possibly leading to data corruption. This plugs
that hole.
Masahiko Sawada, reviewed by Jeff Janes, Bruce Momjian, Simon Riggs,
Michael Paquier, Andres Freund, me, and others.
We've not found a use for this so far, and the current need, which
is to convert the visibility map to a new format, does not suit the
existing design anyway. So just rip it out.
Author: Masahiko Sawada, slightly revised by me.
Discussion: 20160215211313.GB31273@momjian.us
Also fix getErrorText() to return the right error string on failure.
This behavior now matches that of other operating systems.
Report by Noah Misch
Backpatch through 9.1
Bruce Momjian
Tom Lane
Alvaro Herrera
Robert Haas
Peter Eisentraut