This patch doesn't put the new infrastructure to use anywhere, and
indeed it's not clear how it could ever be used for something like
postgres_fdw which has to send an SQL query and wait for a reply,
but there might be FDWs or custom scan providers that are CPU-bound,
so let's give them a way to join club parallel.

KaiGai Kohei, reviewed by me.

Commit 7d17e683 introduced an external
link.

Commit e09996ff removed some ad-hoc code in hstore_to_json_loose
that determined whether an hstore value string looked like a number,
in favor of calling the JSON parser's is-it-a-number code.  However,
it neglected the fact that the exact same code appeared in
hstore_to_jsonb_loose.

This is not a bug, exactly, because the requirements on the two functions
are not the same: hstore_to_json_loose must accept only syntactically legal
JSON numbers as numbers, or it will produce invalid JSON output, as per bug
#12070 which spawned the prior commit.  But hstore_to_jsonb_loose could
accept anything that numeric_in will eat, other than Inf and NaN.

Nonetheless it seems surprising and arbitrary that the two functions don't
use the same rules for what is a number versus what is a string; especially
since they did use the same rules before the aforesaid commit.  For one
thing, that means that doing hstore_to_json_loose and then casting to jsonb
can produce results different from doing just hstore_to_jsonb_loose.

Hence, change hstore_to_jsonb_loose's logic to match hstore_to_json_loose,
ie, hstore values are treated as numbers when they match the JSON syntax
for numbers.

No back-patch, since this is more in the nature of a definitional change
than a bug fix.

Remove duplicate assignment.  This part by Ashutosh Bapat.

Remove now-obsolete comment.  This part by me, although the pending
join pushdown patch does something similar, and for the same reason:
there's no reason to keep two lists of the things in the fdw_private
structure that have to be kept in sync with each other.

You can't really do anything useful with this in the form it currently
exists; among other problems, there's no way to reread whatever
information might be produced when the path is output.  Work is
underway to replace this with a more useful and more general system of
extensible nodes, but let's start by getting rid of this bit.

Extracted from a larger patch by KaiGai Kohei.

The default fetch size of 100 rows might not be right in every
environment, so allow users to configure it.

Corey Huinker, reviewed by Kyotaro Horiguchi, Andres Freund, and me.

Commit e09996ff was one brick shy of a load: it didn't insist
that the detected JSON number be the whole of the supplied string.
This allowed inputs such as "2016-01-01" to be misdetected as valid JSON
numbers.  Per bug #13906 from Dmitry Ryabov.

In passing, be more wary of zero-length input (I'm not sure this can
happen given current callers, but better safe than sorry), and do some
minor cosmetic cleanup.

Insert sd_notify() calls at server start and stop for integration with
systemd.  This allows the use of systemd service units of type "notify",
which greatly simplifies the systemd configuration.
Reviewed-by: Pavel Stěhule <pavel.stehule@gmail.com>

Previously, the first error seen would be that postgresql.conf does not
exist.  But for the case where the whole directory does not exist, give
an error message about that, together with a hint for how to create one.

This field was included in the original definition of the printQueryOpt
struct in commit a45195a1, but it was not used anywhere in that
commit, nor since then.  Spotted by Dickson S. Guedes.

create_foreignscan_plan needs to know whether any system columns are
requested from a relation (this flag is needed by ForeignNext during
execution).  However, for join relations this is a pointless test,
because it's not possible to request system columns from them, so
remove the check.

Author: Etsuro Fujita
Discussion: http://www.postgresql.org/message-id/56AA0FC5.9000207@lab.ntt.co.jp
Reviewed-by: David Rowley, Robert Haas

Apparently at least one committer hasn't gotten the word that these do not
need to be maintained by hand, since initdb will create them automatically.
Noted while fixing bug #13905.

No catversion bump since the post-initdb state is exactly the same either
way.  I don't see a need for back-patch, either.

All the other jsonb function descriptions refer to the arguments as being
"jsonb", but these two said "json".  Make it consistent.  Per bug #13905
from Petru Florin Mihancea.

No catversion bump --- we can't force one in the back branches, and this
isn't very critical anyway.

KNN GiST with recheck flag should return to executor the same type as ordering
operator, GiST detects this type by looking to return type of function which
implements ordering operator. But occasionally detecting code works after
replacing ordering operator function to distance support function.
Distance support function always returns float8, so, detecting code get float8
instead of actual return type of ordering operator.

Built-in opclasses don't have ordering operator which doesn't return
non-float8 value, so, tests are impossible here, at least now.

Backpatch to 9.5 where lozzy KNN was introduced.

Author: Alexander Korotkov
Report by: Artur Zakirov

This makes the values more stable, which seems like a good thing for
anybody who needs to look at at them.

Alexander Korotkov and Amit Kapila

Provide per-script statistical info (count of transactions executed
under that script, average latency for the whole script) after a
multi-script run, adding an intermediate level of detail to existing
global stats and per-command stats.

Author: Fabien Coelho
Reviewer: Michaël Paquier, Álvaro Herrera

Dividing INT_MIN by -1 or taking INT_MIN modulo -1 can sometimes
cause floating-point exceptions or otherwise misbehave.

Fabien Coelho and Michael Paquier

Add
- ALTER SYSTEM SET/RESET ... -> GUC variables
- ALTER TABLE ... SET WITH -> OIDS
- ALTER DATABASE/FUNCTION/ROLE/USER ... SET/RESET -> GUC variables
- ALTER DATABASE/FUNCTION/ROLE/USER ... SET ... -> FROM CURRENT/TO
- ALTER DATABASE/FUNCTION/ROLE/USER ... SET ... TO/= -> possible values

Author: Fujii Masao
Reviewed-by: Michael Paquier, Masahiko Sawada

which is a preprocessor directive. This leads ecpg to incorrectly parse the comment as nested.

Author: Michael Paquier

Error reported by Igal Sapir.

The code that generates a complete SQL query for a given foreign relation
was repeated in two places, and they didn't quite agree: the EXPLAIN case
left out the locking clause.  Centralize the code so we get the same
behavior everywhere, and adjust calling conventions and which functions
are static vs. extern accordingly .  Centralize the code so we get the same
behavior everywhere, and adjust calling conventions and which functions
are static vs. extern accordingly.

Ashutosh Bapat, reviewed and slightly adjusted by me.

This is following in a long train of similar changes and for the same
reasons - see b319356f and
fe702a7b inter alia.

Author: Amit Kapila
Reviewed-by: Alexander Korotkov, Robert Haas

Previously, each PGPROC's backendLock was part of the main tranche,
and the PGPROC just contained a pointer.  Now, the actual LWLock is
part of the PGPROC.

As with previous, similar patches, this makes it significantly easier
to identify these lwlocks in LWLOCK_STATS or Trace_lwlocks output
and improves modularity.

Author: Ildus Kurbangaliev
Reviewed-by: Amit Kapila, Robert Haas

This doesn't add any functionality but just shuffles things around so
that it can be reused and improved later.

Author: Fabien Coelho
Reviewed-by: Michael Paquier, Álvaro Herrera

listForeignTables' invocation of processSQLNamePattern did not match up
with the other ones that handle potentially-schema-qualified names; it
failed to make use of pg_table_is_visible() and also passed the name
arguments in the wrong order.  Bug seems to have been aboriginal in commit
0d692a0d.  It accidentally sort of worked as long as you didn't
inquire too closely into the behavior, although the silliness was later
exposed by inconsistencies in the test queries added by 59efda3e
(which I probably should have questioned at the time, but didn't).

Per bug #13899 from Reece Hart.  Patch by Reece Hart and Tom Lane.
Back-patch to all affected branches.

Patch-by: Oleksandr Shulgin
Reviewed-by: Craig Ringer and Fujii Masao
Backpatch-through: 9.4 where logical decoding was introduced

The upcoming patch to allow join pushdown in postgres_fdw needs to use
this code multiple times, which requires moving it to deparse.c.  That
seems like a good idea anyway, so do that now both on general principle
and to simplify the future patch.

Inspired by a patch by Shigeru Hanada and Ashutosh Bapat, but I did
it a little differently than what that patch did.

Previously, the foreign join pushdown infrastructure left the question
of security entirely up to individual FDWs, but it would be easy for
a foreign data wrapper to inadvertently open up subtle security holes
that way.  So, make it the core code's job to determine which user
mapping OID is relevant, and don't attempt join pushdown unless it's
the same for all relevant relations.

Per a suggestion from Tom Lane.  Shigeru Hanada and Ashutosh Bapat,
reviewed by Etsuro Fujita and KaiGai Kohei, with some further
changes by me.

This fix accidentally got left out of the previous commit.

Previously, postgres_fdw's connection cache was keyed by user OID and
server OID, but this can lead to multiple connections when it's not
really necessary.  In particular, if all relevant users are mapped to
the public user mapping, then their connection options are certainly
the same, so one connection can be used for all of them.

While we're cleaning things up here, drop the "server" argument to
GetConnection(), which isn't really needed.  This saves a few cycles
because callers no longer have to look this up; the function itself
does, but only when establishing a new connection, not when reusing
an existing one.

Ashutosh Bapat, with a few small changes by me.

Patch-by: Filip Rembiałkowski
Reviewed-by: Robert Haas
Backpatch-through: 9.5

The documentation mentioned contrib/ but the module was moved to
src/test/modules/ by commit 22dfd116 of 9.5 era.

Problem pointed out by Dickson Guedes in bug #13896
Backpatch-to: 9.5.

overriden -> overridden

The misspelling in create_extension.sgml was introduced in b67aaf21,
so no need to backpatch.

This function cleans up the pending list of the GIN index by
moving entries in it to the main GIN data structure in bulk.
It returns the number of pages cleaned up from the pending list.

This function is useful, for example, when the pending list
needs to be cleaned up *quickly* to improve the performance of
the search using GIN index. VACUUM can do the same thing, too,
but it may take days to run on a large table.

Jeff Janes,
reviewed by Julien Rouhaud, Jaime Casanova, Alvaro Herrera and me.

Discussion: CAMkU=1x8zFkpfnozXyt40zmR3Ub_kHu58LtRmwHUKRgQss7=iQ@mail.gmail.com

Per off-list discussion with Tom Lane and Michael Paquier, Coverity
gets unhappy if this is not done.

Fixes a defect in commit a7de3dc5.

David Rowley, per report from Jeff Janes, who also checked that the
fix works.