Change ParseConfigFp() so that it doesn't process unused entry of each parameter.

When more than one setting entries of same parameter exist in the
configuration file, PostgreSQL uses only entry appearing last in
configuration file scan. Since the other entries are not used,
ParseConfigFp() doesn't need to process them, but previously it did
that. This problematic behavior caused the configuration file scan
to detect invalid settings of unused entries (e.g., existence of
multiple entries of PGC_POSTMASTER parameter) and log the messages
complaining about them.

This commit changes the configuration file scan so that it processes
only last entry of each parameter.

Note that when multiple entries of same parameter exist both in
postgresql.conf and postgresql.auto.conf, unused entries in
postgresql.conf are still processed only at postmaster startup.

The problem has existed since old version, but a user is more likely
to encounter it since 9.4 where ALTER SYSTEM command was introduced.
So back-patch to 9.4.

Amit Kapila, slightly modified by me. Per report from Christoph Berg.
Refactor pg_receivexlog main loop code, for readability, take 2.

Previously the source codes for processing the received data and handling
the end of stream were included in pg_receivexlog main loop. This commit
splits out them as separate functions. This is useful for improving the
readability of main loop code and making the future pg_receivexlog-related
patch simpler.
Fix alternate regression test output file.

Commit 0ef99bdce3a6cd3195d7df12093042c16328c71c broke this.

Jeff Janes
Don't require sort support functions to provide a comparator.

This could be useful for datatypes like text, where we might want
to optimize for some collations but not others.  However, this patch
doesn't introduce any new sortsupport functions that work this way;
it merely revises the code so that future patches may do so.

Patch by me.  Review by Peter Geoghegan.
Add PG_RETURN_UINT16 macro.

Manuel Kniep
Improve comment.

Based on the old comment, it took me a while to figure out what the
problem was. The importnat detail is that SSL_read() can return WANT_READ
even though some raw data was received from the socket.
pg_upgrade: prevent oid conflicts with new-cluster TOAST tables

Previously, TOAST tables only required in the new cluster could cause
oid conflicts if they were auto-numbered and a later conflicting oid had
to be assigned.

Backpatch through 9.3
Fix typo in docs.

s/XIDs XIDs/XIDs/ in one place in maintenance.sgml.

Guillaume Lelarge
Add -F option to pg_receivexlog, for specifying fsync interval.

This allows us to specify the maximum time to issue fsync to ensure
the received WAL file is safely flushed to disk. Without this,
pg_receivexlog always flushes WAL file only when it's closed and
which can cause WAL data to be lost at the event of a crash.

Furuya Osamu, heavily modified by me.
Small message fixes
Reject duplicate column names in foreign key referenced-columns lists.

Such cases are disallowed by the SQL spec, and even if we wanted to allow
them, the semantics seem ambiguous: how should the FK columns be matched up
with the columns of a unique index?  (The matching could be significant in
the presence of opclasses with different notions of equality, so this issue
isn't just academic.)  However, our code did not previously reject such
cases, but instead would either fail to match to any unique index, or
generate a bizarre opclass-lookup error because of sloppy thinking in the
index-matching code.

David Rowley
Further cleanup of JSON-specific error messages.

Fix an obvious typo in json_build_object()'s complaint about invalid
number of arguments, and make the errhint a bit more sensible too.

Per discussion about how to word the improved hint, change the few places
in the documentation that refer to JSON object field names as "names" to
say "keys" instead, since that's what we've said in the vast majority of
places in the docs.  Arguably "name" is more correct, since that's the
terminology used in RFC 7159; but we're stuck with "key" in view of the
naming of json_object_keys() so let's at least be self-consistent.

I adjusted a few code comments to match this as well, and failed to
resist the temptation to clean up some odd whitespace choices in the
same area, as well as a useless duplicate PG_ARGISNULL() check.  There's
still quite a bit of code that uses the phrase "field name" in non-user-
visible ways, so I left those usages alone.
Clean up handling of unknown-type inputs in json_build_object and friends.

There's actually no need for any special case for unknown-type literals,
since we only need to push the value through its output function and
unknownout() works fine.  The code that was here was completely bizarre
anyway, and would fail outright in cases that should work, not to mention
suffering from some copy-and-paste bugs.
Clarify type resolution behavior for domain types.

The user documentation was vague and not entirely accurate about how
we treat domain inputs for ambiguous operators/functions.  Clarify
that, and add an example and some commentary.  Per a recent question
from Adam Mackler.

It's acted like this ever since we added domains, so back-patch
to all supported branches.
Break out OpenSSL-specific code to separate files.

This refactoring is in preparation for adding support for other SSL
implementations, with no user-visible effects. There are now two #defines,
USE_OPENSSL which is defined when building with OpenSSL, and USE_SSL which
is defined when building with any SSL implementation. Currently, OpenSSL is
the only implementation so the two #defines go together, but USE_SSL is
supposed to be used for implementation-independent code.

The libpq SSL code is changed to use a custom BIO, which does all the raw
I/O, like we've been doing in the backend for a long time. That makes it
possible to use MSG_NOSIGNAL to block SIGPIPE when using SSL, which avoids
a couple of syscall for each send(). Probably doesn't make much performance
difference in practice - the SSL encryption is expensive enough to mask the
effect - but it was a natural result of this refactoring.

Based on a patch by Martijn van Oosterhout from 2006. Briefly reviewed by
Alvaro Herrera, Andreas Karlsson, Jeff Janes.
Fix documentation oversights about pageinspect and initialization fork.

The initialization fork was added in 9.1, but has not been taken into
consideration in documents of get_raw_page function in pageinspect and
storage layout. This commit fixes those oversights.

get_raw_page can read not only a table but also an index, etc. So it
should be documented that the function can read any relation. This commit
also fixes the document of pageinspect that way.

Back-patch to 9.1 where those oversights existed.

Vik Fearing, review by MauMau
Add tab-completion for \unset and valid setting values of psql variables.

This commit also changes tab-completion for \set so that it displays
all the special variables like COMP_KEYWORD_CASE. Previously it displayed
only variables having the set values. Which was not user-friendly for
those who want to set the unset variables.

This commit also changes tab-completion for :variable so that only the
variables having the set values are displayed. Previously even unset
variables were displayed.

Pavel Stehule, modified by me.
Change first call of ProcessConfigFile so as to process only data_directory.

When both postgresql.conf and postgresql.auto.conf have their own entry of
the same parameter, PostgreSQL uses the entry in postgresql.auto.conf because
it appears last in the configuration scan. IOW, the other entries which appear
earlier are ignored. But, previously, ProcessConfigFile() detected the invalid
settings of even those unused entries and emitted the error messages
complaining about them, at postmaster startup. Complaining about the entries
to ignore is basically useless.

This problem happened because ProcessConfigFile() was called twice at
postmaster startup and the first call read only postgresql.conf. That is, the
first call could check the entry which might be ignored eventually by
the second call which read both postgresql.conf and postgresql.auto.conf.
To work around the problem, this commit changes ProcessConfigFile so that
its first call processes only data_directory and the second one does all the
entries. It's OK to process data_directory in the first call because it's
ensured that data_directory doesn't exist in postgresql.auto.conf.

Back-patch to 9.4 where postgresql.auto.conf was added.

Patch by me. Review by Amit Kapila
Enhance pgbench's option checking.

Now benchmarking options such as -c cannot be used if initializing
option (-i) is specified.  Also initializing options such as -F cannot
be used if initializing option is not specified.

Tatsuo Ishii and Fabien COELHO.
Be less aggressive in asking for feedback of logical walsender clients.

When doing logical decoding using START_LOGICAL_REPLICATION in a
walsender process the walsender sometimes was sending out keepalive
messages too frequently. Asking for feedback every time.

WalSndWaitForWal() sends out keepalive messages when it's waiting for
new WAL to be generated locally when it sees that the remote side
hasn't yet flushed WAL up to the local position. That generally is
good but causes problems if the remote side only writes but doesn't
flush changes yet. So check for both remote write and flush position.

Additionally we've asked for feedback to the keepalive message which
isn't warranted when waiting for WAL in contrast to preventing
timeouts because of wal_sender_timeout.

Complaint and patch by Steve Singer.