This was discussed in connection with the patch to avoid inserting no-op
Result nodes, but not actually implemented therein.

Due to a misreading of the function's comment block, there was an
unneeded change to a call in rewriteDefine.c.  There is, in fact
no reason to pass false for a MV; it should be true just like a
view.

Fixes issue pointed out by Tom Lane

This would have caught a bug in the initial patch, and seems like
a good thing to test going forward.

Per bug report by Erik Rijkers and fix by Tom Lane

Even though this patch had no user-visible difference, better keep the code
in psqlscan.l sync with the backend lexer. And of course it's nice to shrink
the psql binary, too. Ecpg's version of the lexer doesn't have the error
rule, it doesn't try to avoid backing up, so it doesn't need to be modified.

As reminded by Tom Lane

Fix unportable use of isdigit(), get rid of useless calculations.

The planner sometimes inserts Result nodes to perform column projections
(ie, arbitrary scalar calculations) above plan nodes that lack projection
logic of their own.  However, we did that even if the lower plan node was
in fact producing the required column set already; which is a pretty common
case given the popularity of "SELECT * FROM ...".  Measurements show that
the useless plan node adds non-negligible overhead, especially when there
are many columns in the result.  So add a check to avoid inserting a Result
node unless there's something useful for it to do.

There are a couple of remaining places where unnecessary Result nodes
could get inserted, but they are (a) much less performance-critical,
and (b) coded in such a way that it's hard to avoid inserting a Result,
because the desired tlist is changed on-the-fly in subsequent logic.
We'll leave those alone for now.

Kyotaro Horiguchi; reviewed and further hacked on by Amit Kapila and
Tom Lane.

The error rule used to avoid backtracking with the U&'...' UESCAPE 'x'
syntax bloated the flex tables, so refactor that. This patch makes the error
rule shorter, by introducing a new exclusive flex state that's entered after
parsing U&'...'. This shrinks the postgres binary by about 220kB.

The estimates are based on the existing lower bound histogram, and a new
histogram of range lengths.

Bump catversion, because the range length histogram now needs to be present
in statistic slot kind 6, or you get an error on @> and <@ queries. (A
re-ANALYZE would be enough to fix that, though)

Alexander Korotkov, with some refactoring by me.

Pavel Stěhule

Reports and suggested patches from Fujii Masao and Andrew Dunstan.

Andrew Dunstan

Treat expressions as being remotely executable only if all collations used
in them are determined by Vars of the foreign table.  This means that, if
the foreign server gets different answers than we do, it's the user's fault
for not having marked the foreign table columns with collations equivalent
to the remote table's.  This rule allows most simple expressions such as
"var < 'constant'" to be sent to the remote side, because the constant
isn't determining the collation (the Var's collation would win).  There's
still room for improvement, but it's hard to see how to do it without a
lot more knowledge and/or assumptions about what the remote side will do.

Mention that PlanForeignModify's result must be copiable by copyObject.

Adopt the position that only locally-defined defaults matter.  Any defaults
defined in the remote database do not affect insertions performed through
a foreign table (unless they are for columns not known to the foreign
table).  While it'd arguably be more useful to permit remote defaults to be
used, making that work in a consistent fashion requires far more work than
seems possible for 9.3.

There's still some discussion about exactly how postgres_fdw ought to
handle this case, but there seems no debate that we want to allow defaults
to be used for inserts into foreign tables.  So remove the core-code
restrictions that prevented it.

While at it, get rid of the special grammar productions for CREATE FOREIGN
TABLE, and instead add explicit FEATURE_NOT_SUPPORTED error checks for the
disallowed cases.  This makes the grammar a shade smaller, and more
importantly results in much more intelligible error messages for
unsupported cases.  It's also one less thing to fix if we ever start
supporting constraints on foreign tables.

Apparently I lost some of the edits I had done on this page for commit
0ac5ad51.

Per note from Etsuro Fujita, although I didn't use his patch.

Make some of the wording in the affected section a bit more complete,
too.

A test intended to provoke an error on the remote side was coded in such
a way that multiple rows should be updated, so the output would vary
depending on which one was processed first.  Per buildfarm.

For datatypes whose output formatting depends on one or more GUC settings,
we have to worry about whether the other server will interpret the value
the same way it was meant.  pg_dump has been aware of this hazard for a
long time, but postgres_fdw needs to deal with it too.  To fix data
retrieval from the remote server, set the necessary remote GUC settings at
connection startup.  (We were already assuming that settings made then
would persist throughout the remote session.)  To fix data transmission to
the remote server, temporarily force the relevant GUCs to the right values
when we're about to convert any data values to text for transmission.

This is all pretty grotty, and not very cheap either.  It's tempting to
think of defining one uber-GUC that would override any settings that might
render printed data values unportable.  But of course, older remote servers
wouldn't know any such thing and would still need this logic.

While at it, revert commit f7951eef, since
this provides a real fix.  (The timestamptz given in the error message
returned from the "remote" server will now reliably be shown in UTC.)

"INSERT INTO foo() VALUES ()" is invalid syntax, so don't do that.

"break" instead of "continue" suppressed view expansion for views appearing
later in the range table.  Per report from Erikjan Rijkers.

While at it, improve the associated comment a bit.

This adds the following:

    json_agg(anyrecord) -> json
    to_json(any) -> json
    hstore_to_json(hstore) -> json (also used as a cast)
    hstore_to_json_loose(hstore) -> json

The last provides heuristic treatment of numbers and booleans.

Also, in json generation, if any non-builtin type has a cast to json,
that function is used instead of the type's output function.

Andrew Dunstan, reviewed by Steve Singer.

Catalog version bumped.

suggested by Tianyin Xu

We probably need to tell the remote server to use specific timezone and
datestyle settings, and maybe other things.  But for now let's just hack
the postgres_fdw regression test to not provoke failures when run in
non-EST5EDT environments.  Per buildfarm.

This patch adds the core-system infrastructure needed to support updates
on foreign tables, and extends contrib/postgres_fdw to allow updates
against remote Postgres servers.  There's still a great deal of room for
improvement in optimization of remote updates, but at least there's basic
functionality there now.

KaiGai Kohei, reviewed by Alexander Korotkov and Laurenz Albe, and rather
heavily revised by Tom Lane.

Instead of just reporting which user failed to log in, log both the
line number in the active pg_hba.conf file (which may not match reality
in case the file has been edited and not reloaded) and the contents of
the matching line (which will always be correct), to make it easier
to debug incorrect pg_hba.conf files.

The message to the client remains unchanged and does not include this
information, to prevent leaking security sensitive information.

Reviewed by Tom Lane and Dean Rasheed

Alexander Korotkov, reviewed by Jeff Davis.

The libpgcommon patch made that unnecessary, palloc and friends are now
available in frontend programs too, mapped to plain old malloc.

As pointed out by Alvaro Herrera.

Fujii Masao

The previous coding of this function could get into situations where it
would never terminate, because successive passes would re-add EMPTY arcs
that had been removed by the previous pass.  Rewrite the function
completely using a new algorithm that is guaranteed to terminate, and
also seems to be usually faster than the old one.  Per Tcl bugs 3604074
and 3606683.

Tom Lane and Don Porter

If we were about to enter archive recovery after crash recovery, we scanned
the archive for the latest tli history file, and set the recovery target
timeline to that. However, when we actually tried to read the history file,
we would not fetch the file from the archive, because we were not in archive
recovery yet.

To fix, make readTimeLineHistory and existsTimeLineHistory to always fetch
the file from archive if archive recovery is requested, even if we're not in
archive recovery yet.

Backpatch to 9.2. Mitsumasa KONDO

This saves several catalog lookups per reference.  It's not all that
exciting right now, because we'd managed to minimize the number of places
that need to fetch the data; but the upcoming writable-foreign-tables patch
needs this info in a lot more places.

KaiGai Kohei

It needs parsenodes.h to be compilable regardless of previous headers.

This page with no tuples is used to distinguish an MV containing a
zero-row resultset of its backing query from an MV which has not
been populated by its backing query.  Unless WAL-logged, recovery
and hot standby don't work correctly with what should be an empty
but scannable materialized view.

Fixes bugs reported by Fujii Masao in testing MVs on hot standby.

Per report and suggestion from Bernd Helmle