Improve pl/pgsql to support composite-type expressions in RETURN.

For some reason lost in the mists of prehistory, RETURN was only coded to
allow a simple reference to a composite variable when the function's return
type is composite.  Allow an expression instead, while preserving the
efficiency of the original code path in the case where the expression is
indeed just a composite variable's name.  Likewise for RETURN NEXT.

As is true in various other places, the supplied expression must yield
exactly the number and data types of the required columns.  There was some
discussion of relaxing that for pl/pgsql, but no consensus yet, so this
patch doesn't address that.

Asif Rehman, reviewed by Pavel Stehule
Clarify that COPY FREEZE is not a hard rule.
Remove message when FREEZE not honoured,
clarify reasons in comments and docs.
Optimize COPY FREEZE with CREATE TABLE also.

Jeff Davis, additional test by me
Correct xmax test for COPY FREEZE
Improve pg_upgrade's status display

Pg_upgrade displays file names during copy and database names during
dump/restore.  Andrew Dunstan identified three bugs:

*  long file names were being truncated to 60 _leading_ characters, which
   often do not change for long file names

*  file names were truncated to 60 characters in log files

*  carriage returns were being output to log files

This commit fixes these --- it prints 60 _trailing_ characters to the
status display, and full path names without carriage returns to log
files.  It also suppresses status output to the log file unless verbose
mode is used.
Update iso.org page link

The old one is responding with 404.
Support automatically-updatable views.

This patch makes "simple" views automatically updatable, without the need
to create either INSTEAD OF triggers or INSTEAD rules.  "Simple" views
are those classified as updatable according to SQL-92 rules.  The rewriter
transforms INSERT/UPDATE/DELETE commands on such views directly into an
equivalent command on the underlying table, which will generally have
noticeably better performance than is possible with either triggers or
user-written rules.  A view that has INSTEAD OF triggers or INSTEAD rules
continues to operate the same as before.

For the moment, security_barrier views are not considered simple.
Also, we do not support WITH CHECK OPTION.  These features may be
added in future.

Dean Rasheed, reviewed by Amit Kapila
Fix assorted bugs in privileges-for-types patch.

Commit 729205571e81b4767efc42ad7beb53663e08d1ff added privileges on data
types, but there were a number of oversights.  The implementation of
default privileges for types missed a few places, and pg_dump was
utterly innocent of the whole concept.  Per bug #7741 from Nathan Alden,
and subsequent wider investigation.
Fix the tracking of min recovery point timeline.

Forgot to update it at the right place. Also, consider checkpoint record
that switches to new timelne to be on the new timeline.

This fixes erroneous "requested timeline 2 does not contain minimum recovery
point" errors, pointed out by Amit Kapila while testing another patch.
Update minimum recovery point on truncation.

If a file is truncated, we must update minRecoveryPoint. Once a file is
truncated, there's no going back; it would not be safe to stop recovery
at a point earlier than that anymore.

Per report from Kyotaro HORIGUCHI. Backpatch to 8.4. Before that,
minRecoveryPoint was not updated during recovery at all.
doc: Remove blastwave.org link

Apparently, this service has been dead since 2008.
Fix pg_upgrade -O/-o options

Fix previous commit that added synchronous_commit=off, but broke -O/-o
due to missing space in argument passing.

Backpatch to 9.2.
Add mode where contrib installcheck runs each module in a separately named database.

Normally each module is tested in a database named contrib_regression,
which is dropped and recreated at the beginhning of each pg_regress run.
This new mode, enabled by adding USE_MODULE_DB=1 to the make command
line, runs most modules in a database with the module name embedded in
it.

This will make testing pg_upgrade on clusters with the contrib modules
a lot easier.

Second attempt at this, this time accomodating make versions older
than 3.82.

Still to be done: adapt to the MSVC build system.

Backpatch to 9.0, which is the earliest version it is reasonably
possible to test upgrading from.
Consistency check should compare last record replayed, not last record read.

EndRecPtr is the last record that we've read, but not necessarily yet
replayed. CheckRecoveryConsistency should compare minRecoveryPoint with the
last replayed record instead. This caused recovery to think it's reached
consistency too early.

Now that we do the check in CheckRecoveryConsistency correctly, we have to
move the call of that function to after redoing a record. The current place,
after reading a record but before replaying it, is wrong. In particular, if
there are no more records after the one ending at minRecoveryPoint, we don't
enter hot standby until one extra record is generated and read by the
standby, and CheckRecoveryConsistency is called. These two bugs conspired
to make the code appear to work correctly, except for the small window
between reading the last record that reaches minRecoveryPoint, and
replaying it.

In the passing, rename recoveryLastRecPtr, which is the last record
replayed, to lastReplayedEndRecPtr. This makes it slightly less confusing
with replayEndRecPtr, which is the last record read that we're about to
replay.

Original report from Kyotaro HORIGUCHI, further diagnosis by Fujii Masao.
Backpatch to 9.0, where Hot Standby subtly changed the test from
"minRecoveryPoint < EndRecPtr" to "minRecoveryPoint <= EndRecPtr". The
former works because where the test is performed, we have always read one
more record than we've replayed.
Fix pg_upgrade for invalid indexes

All versions of pg_upgrade upgraded invalid indexes caused by CREATE
INDEX CONCURRENTLY failures and marked them as valid.  The patch adds a
check to all pg_upgrade versions and throws an error during upgrade or
--check.

Backpatch to 9.2, 9.1, 9.0.  Patch slightly adjusted.
Fix performance problems with autovacuum truncation in busy workloads.

In situations where there are over 8MB of empty pages at the end of
a table, the truncation work for trailing empty pages takes longer
than deadlock_timeout, and there is frequent access to the table by
processes other than autovacuum, there was a problem with the
autovacuum worker process being canceled by the deadlock checking
code. The truncation work done by autovacuum up that point was
lost, and the attempt tried again by a later autovacuum worker. The
attempts could continue indefinitely without making progress,
consuming resources and blocking other processes for up to
deadlock_timeout each time.

This patch has the autovacuum worker checking whether it is
blocking any other thread at 20ms intervals. If such a condition
develops, the autovacuum worker will persist the work it has done
so far, release its lock on the table, and sleep in 50ms intervals
for up to 5 seconds, hoping to be able to re-acquire the lock and
try again. If it is unable to get the lock in that time, it moves
on and a worker will try to continue later from the point this one
left off.

While this patch doesn't change the rules about when and what to
truncate, it does cause the truncation to occur sooner, with less
blocking, and with the consumption of fewer resources when there is
contention for the table's lock.

The only user-visible change other than improved performance is
that the table size during truncation may change incrementally
instead of just once.

This problem exists in all supported versions but is infrequently
reported, although some reports of performance problems when
autovacuum runs might be caused by this. Initial commit is just the
master branch, but this should probably be backpatched once the
build farm and general developer usage confirm that there are no
surprising effects.

Jan Wieck
Disable event triggers in standalone mode.

Per discussion, this seems necessary to allow recovery from broken event
triggers, or broken indexes on pg_event_trigger.

Dimitri Fontaine
Add defenses against integer overflow in dynahash numbuckets calculations.

The dynahash code requires the number of buckets in a hash table to fit
in an int; but since we calculate the desired hash table size dynamically,
there are various scenarios where we might calculate too large a value.
The resulting overflow can lead to infinite loops, division-by-zero
crashes, etc.  I (tgl) had previously installed some defenses against that
in commit 299d1716525c659f0e02840e31fbe4dea3, but that covered only one
call path.  Moreover it worked by limiting the request size to work_mem,
but in a 64-bit machine it's possible to set work_mem high enough that the
problem appears anyway.  So let's fix the problem at the root by installing
limits in the dynahash.c functions themselves.

Trouble report and patch by Jeff Davis.
In multi-insert, don't go into infinite loop on a huge tuple and fillfactor.

If a tuple is larger than page size minus space reserved for fillfactor,
heap_multi_insert would never find a page that it fits in and repeatedly ask
for a new page from RelationGetBufferForTuple. If a tuple is too large to
fit on any page, taking fillfactor into account, RelationGetBufferForTuple
will always expand the relation. In a normal insert, heap_insert will accept
that and put the tuple on the new page. heap_multi_insert, however, does a
fillfactor check of its own, and doesn't accept the newly-extended page
RelationGetBufferForTuple returns, even though there is no other choice to
make the tuple fit.

Fix that by making the logic in heap_multi_insert more like the heap_insert
logic. The first tuple is always put on the page RelationGetBufferForTuple
gives us, and the fillfactor check is only applied to the subsequent tuples.

Report from David Gould, although I didn't use his patch.