"People's Republic of China" locale on Windows was causing initdb to fail.

This fixes bug #5818 reported by yulei. On master, this makes the mapping
of "People's Republic of China" to just "China" obsolete. In 9.0 and 8.4,
just fix the escaping. Earlier versions didn't have locale names in bki
file.

If someone removes the 'postgres' database from the old cluster and the
new cluster has a 'postgres' database, the number of databases will not
match.  We actually could upgrade such a setup, but it would violate the
1-to-1 mapping of database counts, so we throw an error instead.

Previously they got an error during the upgrade, and not at the check
stage; PG 9.0.4 does the same.

Add C comment about why we throw an error if the pg_upgrade old/new
database counts don't match.

There can never be a need to push the indcheckxmin horizon forward, since
any HOT chains that are actually broken with respect to the index must
pre-date its original creation.  So we can just avoid changing pg_index
altogether during a REINDEX operation.

This offers a cleaner solution than my previous patch for the problem
found a few days ago that we mustn't try to update pg_index while we are
reindexing it.  System catalog indexes will always be created with
indcheckxmin = false during initdb, and with this modified code we should
never try to change their pg_index entries.  This avoids special-casing
system catalogs as the former patch did, and should provide a performance
benefit for many cases where REINDEX formerly caused an index to be
considered unusable for a short time.

Back-patch to 8.3 to cover all versions containing HOT.  Note that this
patch changes the API for index_build(), but I believe it is unlikely that
any add-on code is calling that directly.

This reverts commit 4b6106cc of 2011-04-15.
There's a better way to do it, which will follow shortly.

... for some value of "properly".  Instead of overriding REGRESS_OPTS,
set the variables ENCODING and NO_LOCALE, which is more expressive and
allows overriding by the user.  Fix vcregress.pl to handle that.

This is how build.pl treats it and how it's documented.

While "UTF8" is the correct name for this encoding, existing JDBC drivers
expect that if they send "UNICODE" it will read back the same way; they
fail with an opaque "Protocol error" complaint if not.  This will be fixed
in the 9.1 drivers, but until older drivers are no longer in use in the
wild, we'd better leave "UNICODE" alone.  Continue to canonicalize all
other inputs.  Per report from Steve Singer and subsequent discussion.

Per spec we ought to apply select_common_collation() across the expressions
in each column of the VALUES table.  The original coding was just taking
the first row and assuming it was representative.

This patch adds a field to struct RangeTblEntry to carry the resolved
collations, so initdb is forced for changes in stored rule representation.

This also ensures that we take a relation lock on the composite type when
creating a typed table, which is necessary to prevent the composite type
and the typed table from getting out of step in the face of concurrent
DDL.

Noah Misch, with some changes.

Before commit c016ce72, this wasn't
needed, but now that multiple resource manager IDs can percolate down
through here, we have to make sure we know which one we've got.
Otherwise, we can confuse (for example) an XLOG_XACT_COMMIT record
with an XLOG_CHECKPOINT_SHUTDOWN record.

Review by Jaime Casanova

In \d, be more careful to print collation only if it's not the default for
the column's data type.  Avoid assuming that the name "default" is magic.

Fix \d on a composite type so that it will print per-column collations.
It's no longer the case that a composite type cannot have modifiers.
(In consequence, the expected outputs for composite-type regression tests
change.)

Fix \dD so that it will print collation for a domain, again only if it's
not the same as the base type's collation.

Curiously, it was already documented in ALTER TYPE ADD ATTRIBUTE, but
not here.

CREATE TYPE and ALTER TYPE ADD ATTRIBUTE handle this, so I suppose it's
an intended feature, but pg_dump didn't know about it.

The other DDL operations that create an inheritance relationship were
checking for collation match already, but this one got missed.

Also fix comments that failed to mention collation checks.

This allows the usual rules for assigning a collation to a local variable
to be overridden.  Per discussion, it seems appropriate to support this
rather than forcing all local variables to have the argument-derived
collation.

Fix crash when releasing duplicate entries in the encoding conversion cache
list, caused by releasing the current entry of the list being chased by
foreach().  We have a standard idiom for handling such cases, but this
loop wasn't using it.

This got broken in my recent rewrite of GUC assign hooks.  Not sure how
I missed this when testing the modified code, but I did.  Per report from
Peter.

This might have caught the recent embarrassment over trying to modify
pg_index while its indexes were being rebuilt.

Noah Misch

For what seem entirely historical reasons, a bitmask "flags" argument was
recently added to reindex_relation without subsuming its existing boolean
argument into that bitmask.  This seems a bit bizarre, so fold them
together.

This area was a few bricks shy of a load, and badly under-commented too.
We have to ensure that the generated targetlist entries for a set-operation
node expose the correct collation for each entry, since higher-level
processing expects the tlist to reflect the true ordering of the plan's
output.

This hackery wouldn't be necessary if SortGroupClause carried collation
info ... but making it do so would inject more pain in the parser than
would be saved here.  Still, we might want to rethink that sometime.

This will (hopefully) eliminate the need for the
plpython_unicode_0.out expected file.

The places that attempt to change pg_index.indcheckxmin during a reindexing
operation cannot be executed safely if pg_index itself is the subject of
the operation.  This is the explanation for a couple of recent reports of
VACUUM FULL failing with
	ERROR:  duplicate key value violates unique constraint "pg_index_indexrelid_index"
	DETAIL:  Key (indexrelid)=(2678) already exists.

However, there isn't any real need to update indcheckxmin in such a
situation, if we assume that pg_index can never contain a truly broken HOT
chain.  This assumption holds if new indexes are never created on it during
concurrent operations, which is something we don't consider safe for any
system catalog, not just pg_index.  Accordingly, modify the code to not
manipulate indcheckxmin when reindexing any system catalog.

Back-patch to 8.3, where HOT was introduced.  The known failure scenarios
involve 9.0-style VACUUM FULL, so there might not be any real risk before
9.0, but let's not assume that.

Although rowcount estimates really ought not be NaN, a bug elsewhere
could perhaps result in that, and that would cause Assert failure in
cost_mergejoin, which I believe to be the explanation for bug #5977 from
Anton Kuznetsov.  Seems like a good idea to expend a couple more cycles
to prevent that, even though the real bug is elsewhere.  Not back-patching,
though, because we don't encourage running production systems with
Asserts on.

apostrophes or dots. There isn't much hope of Microsoft fixing it any time
soon, it's been like that for ages, so we better work around it. So, map a
few common Windows locale names known to cause problems to aliases that work.

server-encoding, fall back to UTF-8. It happens at least with the Chinese
locale, which implies BIG5. This is safe, because on Windows all locales
are compatible with UTF-8.

Peter Eisentraut

Anything including Visual Studio 2010 compilers is not yet
supported for building on Windows.

The hash table is seq scanned at transaction end, to release all locks,
and making the hash table larger than necessary makes that slower. With
very simple queries, that overhead can amount to a few percent of the total
CPU time used.

At the moment, backend startup needs 6 locks, and a simple query with one
table and index needs 3 locks. 16 is enough for even quite complicated
transactions, and it will grow automatically if it fills up.

Also refactor things a little bit so that the same methods for setting
test locale and encoding can be used everywhere.

The latest openjade packages for Ubuntu 10.10 seg fault when building
our documentation.

Josh Berkus

The lock level for adding a parent table is now ShareUpdateExclusiveLock;
see commit fbcf4b92.  This comment didn't
get updated to match, but it doesn't seem important to mention this detail
here, so rather than updating it now, just take it out.

Instead of using slightly-too-clever heuristics to decide when we must
create a TOAST table, just check whether one is needed every time the
table is altered.  Checking whether a toast table is needed is cheap
enough that we needn't worry about doing it on every ALTER TABLE command,
and the previous coding is apparently prone to accidental breakage:
commit 04e17bae broken ALTER TABLE ..
SET STORAGE, which moved some actions from AT_PASS_COL_ATTRS to
AT_PASS_MISC, and commit 6c572399 broke
ALTER TABLE .. ADD COLUMN by changing the way that adding columns
recurses into child tables.

Noah Misch, with one comment change by me