Commit 773df883 changed the type of check_option reloption
from string to enum. But it forgot to update the description of
the type in the documentation.

Author: Atsushi Torikoshi
Discussion: https://postgr.es/m/CACZ0uYFvHF4n6yxF390YZgr4Q0Z0c2w0ihu=DLb8ipNOnNcqzQ@mail.gmail.com

This will allow to specifying SQLSTATE error code for the errors in the
missing places.

Reported-by: Sawada Masahiko
Author: Sawada Masahiko
Backpatch-through: 9.5
Discussion: https://postgr.es/m/CA+fd4k6N8EjNvZpM8nme+y+05mz-SM8Z_BgkixzkA34R+ej0Kw@mail.gmail.com

Introduced by 61d7c7bc.

Backpatch-through: 12

relation extension lock.

The only exception to the rule is that we can try to acquire the same
relation extension lock more than once.  This is allowed as we are not
creating any new lock for this case.  This restriction implies that the
relation extension lock won't ever participate in the deadlock cycle
because we can never wait for any other heavyweight lock after acquiring
this lock.

Such a restriction is okay for relation extension locks as unlike other
heavyweight locks these are not held till the transaction end.  These are
taken for a short duration to extend a particular relation and then
released.

Author: Dilip Kumar, with few changes by Amit Kapila
Reviewed-by: Amit Kapila, Kuntal Ghosh and Sawada Masahiko
Discussion: https://postgr.es/m/CAD21AoCmT3cFQUN4aVvzy5chw7DuzXrJCbrjTU05B+Ss=Gn1LA@mail.gmail.com

Copying block and offset numbers to local variables in _bt_insertonpg()
made the code less readable.  Remove the variables.  There is already
code that conditionally calls BufferGetBlockNumber() in the same block,
so consistently do it that way instead.

Calling BufferGetBlockNumber() is very cheap, but we might as well avoid
it when it isn't truly necessary.  It isn't truly necessary for
_bt_insertonpg() to call BufferGetBlockNumber() in almost all cases.

Spotted while working on a patch that refactors the fastpath rightmost
leaf page cache optimization, which was added by commit 2b272734.

For the semantics to match the epoll implementation, we need a socket to
continue to appear readable/writable if you wait multiple times without
doing I/O in between (in Linux terminology: level-triggered rather than
edge-triggered).  This distinction will be important for later commits.
Similar to commit 3b790d25 for Windows.
Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Discussion: https://postgr.es/m/CA%2BhUKGJAC4Oqao%3DqforhNey20J8CiG2R%3DoBPqvfR0vOJrFysGw%40mail.gmail.com

While running under a debugger, macOS's getppid() can return the
debugger's PID.  That could cause a backend to exit because it falsely
believed that the postmaster had died, since commit 815c2f09.

Continue to use getppid() as a fast postmaster check after adding the
postmaster's PID to a kqueue, to close a PID-reuse race, but double
check that it actually exited by trying to read the pipe.  The new check
isn't reached in the common case.
Reported-by: Alexander Korotkov <a.korotkov@postgrespro.ru>
Discussion: https://postgr.es/m/CA%2BhUKGKhAxJ8V8RVwCo6zJaeVrdOG1kFBHGZOOjf6DzW_omeMA%40mail.gmail.com

pg_proc.c and pg_aggregate.c had near-duplicate copies of the logic
to decide whether a function or aggregate's signature is legal.
This seems like a bad thing even without the problem that the
upcoming "anycompatible" patch would roughly double the complexity
of that logic.  Hence, refactor so that the rules are localized
in new subroutines supplied by parse_coerce.c.  (One could quibble
about just where to add that code, but putting it beside
enforce_generic_type_consistency seems not totally unreasonable.)

The fact that the rules are about to change would mandate some
changes in the wording of the associated error messages in any case.
I ended up spelling things out in a fairly literal fashion in the
errdetail messages, eg "A result of type anyelement requires at
least one input of type anyelement, anyarray, anynonarray, anyenum,
or anyrange."  Perhaps this is overkill, but once there's more than
one subgroup of polymorphic types, people might get confused by
more-abstract messages.

Discussion: https://postgr.es/m/24137.1584139352@sss.pgh.pa.us

Use a varlistentry id for the deduplicate_items storage parameter that
is derived from the name of the parameter itself.

This oversight happened because the storage parameter was renamed
relatively late during the development of the patch that became commit
0d861bbb.

Ordinarily it's impossible for an actual input of a function to have
declared type ANYARRAY, since we'd resolve that to a concrete array
type before doing argument type resolution for the function.  But an
exception arises for functions applied to certain columns of pg_statistic
or pg_stats, since we abuse the "anyarray" pseudotype by using it to
declare those columns.  So parse_coerce.c has to deal with the case.

Previously we allowed an ANYARRAY actual input to match an ANYARRAY
polymorphic argument, but only if no other argument or result was
declared ANYELEMENT.  When that logic was written, those were the only
two polymorphic types, and I fear nobody thought carefully about how it
ought to extend to the other ones that came along later.  But actually
it was wrong even then, because if a function has two ANYARRAY
arguments, it should be able to expect that they have identical element
types, and we'd not be able to ensure that.

The correct generalization is that we can match an ANYARRAY actual input
to an ANYARRAY polymorphic argument only if no other argument or result
is of any polymorphic type, so that no promises are being made about
element type compatibility.  check_generic_type_consistency can't test
that condition, but it seems better anyway to accept such matches there
and then throw an error if needed in enforce_generic_type_consistency.
That way we can produce a specific error message rather than an
unintuitive "function does not exist" complaint.  (There's some risk
perhaps of getting new ambiguous-function complaints, but I think that
any set of functions for which that could happen would be ambiguous
against ordinary array columns as well.)  While we're at it, we can
improve the message that's produced in cases that the code did already
object to, as shown in the regression test changes.

Also, remove a similar test that got cargo-culted in for ANYRANGE;
there are no catalog columns of type ANYRANGE, and I hope we never
create any, so that's not needed.  (It was incomplete anyway.)

While here, update some comments and rearrange the code a bit in
preparation for upcoming additions of more polymorphic types.

In practical situations I believe this is just exchanging one error
message for another, hopefully better, one.  So it doesn't seem
needful to back-patch, even though the mistake is ancient.

Discussion: https://postgr.es/m/21569.1584314271@sss.pgh.pa.us

It devolved into a content-less wrapper over read_local_xlog_page, with
nothing to add, plus it's easily confused with walsender's
logical_read_xlog_page.  There doesn't seem to be any reason for it to
stay.

src/include/replication/logicalfuncs.h becomes empty, so remove it too.
The prototypes it initially had were absorbed by generated fmgrprotos.h.

Discussion: https://postgr.es/m/20191115214102.GA15616@alvherre.pgsql

Commit 9f06d79e's replication slot copying failed to
properly reserve the WAL that the slot is expecting to see
during DecodingContextFindStartpoint (to set the confirmed_flush
LSN), so concurrent activity could remove that WAL and cause the
copy process to error out.  But it doesn't actually *need* that
WAL anyway: instead of running decode to find confirmed_flush, it
can be copied from the source slot. Fix this by rearranging things
to avoid DecodingContextFindStartpoint() (leaving the target slot's
confirmed_flush_lsn to invalid), and set that up afterwards by copying
from the target slot's value.

Also ensure the source slot's confirmed_flush_lsn is valid.

Reported-by: Arseny Sher
Author: Masahiko Sawada, Arseny Sher
Discussion: https://postgr.es/m/871rr3ohbo.fsf@ars-thinkpad

I noticed that we completely failed to document the restriction
that an "anyrange" result type has to be inferred from an "anyrange"
input.  The docs also were less clear than they could be about the
relationship between "anyrange" and "anyarray".

It's been like this all along, so back-patch.

It is possible to reach check_sql_fn_retval() with an unresolved
polymorphic rettype, resulting in an assertion failure as demonstrated
by one of the added test cases.  However, the code following that
throws what seems an acceptable error message, so just remove the
Assert and adjust commentary.

While here, I thought it'd be a good idea to provide some parallel
tests of SQL-function and PL/pgSQL-function polymorphism behavior.
Some of these cases are perhaps duplicative of tests elsewhere,
but we hadn't any organized coverage of the topic AFAICS.

Although that assertion's been wrong all along, it won't have any
effect in production builds, so I'm not bothering to back-patch.

Discussion: https://postgr.es/m/21569.1584314271@sss.pgh.pa.us

If pkg-config is installed and knows about libxml2, use its information
rather than asking xml2-config.  Otherwise proceed as before.  This
patch allows "configure --with-libxml" to succeed on platforms that
have pkg-config but not xml2-config, which is likely to soon become
a typical situation.

The old mechanism can be forced by setting XML2_CONFIG explicitly
(hence, build processes that were already doing so will certainly
not need adjustment).  Also, it's now possible to set XML2_CFLAGS
and XML2_LIBS explicitly to override both programs.

There is a small risk of this breaking existing build processes,
if there are multiple libxml2 installations on the machine and
pkg-config disagrees with xml2-config about which to use.  The
only case where that seems really likely is if a builder has tried
to select a non-default xml2-config by putting it early in his PATH
rather than setting XML2_CONFIG.  Plan to warn against that in the
minor release notes.

Back-patch to v10; before that we had no pkg-config infrastructure,
and it doesn't seem worth adding it for this.

Hugh McMaster and Tom Lane; Peter Eisentraut also made an earlier
attempt at this, from which I lifted most of the docs changes.

Discussion: https://postgr.es/m/CAN9BcdvfUwc9Yx5015bLH2TOiQ-M+t_NADBSPhMF7dZ=pLa_iw@mail.gmail.com

Author: Atsushi Torikoshi
Discussion: https://postgr.es/m/CACZ0uYFQebs4WT5eu3dK4qm_2PurZuvB++8nDvSBG0ebRWmbdg@mail.gmail.com

This commit fixes the comment about SharedHotStandbyActive variable.
The comment was apparently copy-and-pasted.

Author: Atsushi Torikoshi
Discussion: https://postgr.es/m/CACZ0uYEjpqZB9wN2Rwc_RMvDybyYqdbkPuDr1NyxJg4f9yGfMw@mail.gmail.com

We don't need to manually clean up allocations in a SRF's
multi_call_memory_ctx, because the SRF_RETURN_DONE infrastructure
takes care of that (and also ensures that it will happen even if the
function never gets a final call, which simple manual cleanup cannot
do).

Hence, the code removed by this patch is a waste of code and cycles.
Worse, it gives the impression that cleaning up manually is a thing,
which can lead to more serious errors such as those fixed in
commits 085b6b66 and b4570d33.  So we should get rid of it.

These are not quite actual bugs though, so I couldn't muster the
enthusiasm to back-patch.  Fix in HEAD only.

Justin Pryzby

Discussion: https://postgr.es/m/20200308173103.GC1357@telsasoft.com

This extends the fixes made in commit 085b6b66 to other SRFs with the
same bug, namely pg_logdir_ls(), pgrowlocks(), pg_timezone_names(),
pg_ls_dir(), and pg_tablespace_databases().

Also adjust various comments and documentation to warn against
expecting to clean up resources during a ValuePerCall SRF's final
call.

Back-patch to all supported branches, since these functions were
all born broken.

Justin Pryzby, with cosmetic tweaks by me

Discussion: https://postgr.es/m/20200308173103.GC1357@telsasoft.com

Oversight in commit d2086b08.

It's strange that a directory-listing function does not list all entries
in a directory, so let's at least document it.  This involves

pg_ls_logdir
pg_ls_waldir
pg_ls_archive_statusdir
pg_ls_tmpdir

Backpatch as far back as it applies cleanly (and as far as as each
function exists).  REL_10_STABLE uses different wording, but hopefully
people are not reading docs so old to write new apps anyway.

Author: Justin Pryzby <pryzby@telsasoft.com>
Discussion: https://postgr.es/m/20200305161838.GJ684@telsasoft.com

I forgot to update it per last-minute edits leading to commit
2f966131.  Reported by Mark Dilger.

Discussion: https://postgr.es/m/DA9A5554-AADD-4F33-96F9-A1066EC9CAB5@enterprisedb.com>

Introduced by b08dee24.  Noted by Coverity.

Refactor nbtinsert.c so that the final itemsz of each new non-pivot
tuple (the MAXALIGN()'d size) is determined once.  Most of the functions
used by leaf page inserts used the insertstate.itemsz value already.
This commit makes everything use insertstate.itemsz as standard
practice.  The goal is to decouple tuple size from "effective" tuple
size.  Making this distinction isn't truly necessary right now, but that
might change in the future.

Also explain why we consistently apply MAXALIGN() to get an effective
index tuple size.  This was rather unclear, in part because it isn't
actually strictly necessary right now.

Introduce a GUC and a tablespace option to control I/O prefetching, much
like effective_io_concurrency, but for work that is done on behalf of
many client sessions.

Use the new setting in heapam.c instead of the hard-coded formula
effective_io_concurrency + 10 introduced by commit 558a9165.  Go with
a default value of 10 for now, because it's a round number pretty close
to the value used for that existing case.

Discussion: https://postgr.es/m/CA%2BhUKGJUw08dPs_3EUcdO6M90GnjofPYrWp4YSLaBkgYwS-AqA%40mail.gmail.com

The effective_io_concurrency GUC and equivalent tablespace option were
previously passed through a formula based on a theory about RAID
spindles and probabilities, to arrive at the number of pages to prefetch
in bitmap heap scans.  Tomas Vondra, Andres Freund and others argued
that it was anachronistic and hard to justify, and commit 558a9165
already started down the path of bypassing it in new code.  We agreed to
drop that logic and use the value directly.

For the default setting of 1, there is no change in effect.  Higher
settings can be converted from the old meaning to the new with:

  select round(sum(OLD / n::float)) from generate_series(1, OLD) s(n);

We might want to consider renaming the GUC before the next release given
the change in meaning, but it's not clear that many users had set it
very carefully anyway.  That decision is deferred for now.

Discussion: https://postgr.es/m/CA%2BhUKGJUw08dPs_3EUcdO6M90GnjofPYrWp4YSLaBkgYwS-AqA%40mail.gmail.com

Relocate _bt_newroot() prototype, so that the order that prototypes
appear in matches the order that the functions are defined in.

The backend type, which corresponds to what
pg_stat_activity.backend_type shows, is added as a column to the
csvlog and can optionally be added to log_line_prefix using the new %b
placeholder.
Reviewed-by: Julien Rouhaud <rjuju123@gmail.com>
Reviewed-by: Kuntal Ghosh <kuntalghosh.2007@gmail.com>
Reviewed-by: Alvaro Herrera <alvherre@2ndquadrant.com>
Reviewed-by: Justin Pryzby <pryzby@telsasoft.com>
Discussion: https://www.postgresql.org/message-id/flat/c65e5196-4f04-4ead-9353-6088c19615a3@2ndquadrant.com

The regression tests for extended statistics were not testing a couple
of important cases for the MCV lists:

  * IS NOT NULL clauses - We did have queries with IS NULL clauses, but
    not the negative case.

  * clauses with variable on the right - All the clauses had the Var on
    the left, i.e. (Var op Const), so this adds (Const op Var) too.

  * columns with fixed-length types passed by reference - All columns
    were using either by-value or varlena types, so add a test with
    UUID columns too. This matters for (de)serialization.

  * NULL-only dimension - When one of the columns contains only NULL
    values, we treat it a a special case during (de)serialization.

  * arrays containing NULL - When the constant parameter contains NULL
    value, we need to handle it correctly during estimation, for all
    IN, ANY and ALL clauses.

Discussion: https://www.postgresql.org/message-id/flat/20200113230008.g67iyk4cs3xbnjju@development
Author: Tomas Vondra

The regression tests for functional dependencies were only using clauses
of the form (Var op Const), i.e. with Var on the left side. This adds
a couple of queries with Var on the right, to test other code paths.

It also prints one of the functional dependencies, to test the data type
output function. The functional dependencies are "perfect" with degree
of 1.0 so this should be stable.

Discussion: https://www.postgresql.org/message-id/flat/20200113230008.g67iyk4cs3xbnjju@development
Author: Tomas Vondra

Commit a5954de1 replaced a lot of manually-coded stub I/O routines
with code generated by macros.  That was a good idea but it didn't
go far enough, because there were still manually-coded stub input
routines for types that had live output routines.  Refactor the
macro so that we can generate just a stub input routine at need.

Also create similar macros to generate stub binary I/O routines,
since we have some of those now.  The only stub functions that remain
hand-coded are shell_in() and shell_out(), which need to be separate
because they use different error messages.

While here, rearrange the commentary to discuss each type not each
function.  This provides a better way to explain the *why* of which
types need which support, rather than just duplicatively annotating
the functions.

Discussion: https://postgr.es/m/24137.1584139352@sss.pgh.pa.us

resolve_polymorphic_tupdesc() and resolve_polymorphic_argtypes() failed to
cover the case of having to resolve anyarray given only an anyrange input.
The bug was masked if anyelement was also used (as either input or
output), which probably helps account for our not having noticed.

While looking at this I noticed that resolve_generic_type() would produce
the wrong answer if asked to make that same resolution.  ISTM that
resolve_generic_type() is confusingly defined and overly complex, so
rather than fix it, let's just make funcapi.c do the specific lookups
it requires for itself.

With this change, resolve_generic_type() is not used anywhere, so remove
it in HEAD.  In the back branches, leave it alone (complete with bug)
just in case any external code is using it.

While we're here, make some other refactoring adjustments in funcapi.c
with an eye to upcoming future expansion of the set of polymorphic types:

* Simplify quick-exit tests by adding an overall have_polymorphic_result
flag.  This is about a wash now but will be a win when there are more
flags.

* Reduce duplication of code between resolve_polymorphic_tupdesc() and
resolve_polymorphic_argtypes().

* Don't bother to validate correct matching of anynonarray or anyenum;
the parser should have done that, and even if it didn't, just doing
"return false" here would lead to a very confusing, off-point error
message.  (Really, "return false" in these two functions should only
occur if the call_expr isn't supplied or we can't obtain data type
info from it.)

* For the same reason, throw an elog rather than "return false" if
we fail to resolve a polymorphic type.

The bug's been there since we added anyrange, so back-patch to
all supported branches.

Discussion: https://postgr.es/m/6093.1584202130@sss.pgh.pa.us

Commit 8f321bd1 added support for estimating ScalarArrayOpExpr clauses
(IN/ANY) clauses using functional dependencies. There's no good reason
not to support estimation of these clauses using multi-variate MCV lists
too, so this commits implements that. That makes the behavior consistent
and MCV lists can estimate all variants (ANY/ALL, inequalities, ...).

Author: Tomas Vondra
Review: Dean Rasheed
Discussion: https://www.postgresql.org/message-id/flat/13902317.Eha0YfKkKy%40pierred-pdoc

Until now functional dependencies supported only simple equality clauses
and clauses that can be trivially translated to equalities. This commit
allows estimation of some ScalarArrayOpExpr (IN/ANY) clauses.

For IN clauses we can do this thanks to using operator with equality
semantics, which means an IN clause

    WHERE c IN (1, 2, ..., N)

can be translated to

    WHERE (c = 1 OR c = 2 OR ... OR c = N)

IN clauses are now considered compatible with functional dependencies,
and rely on the same assumption of consistency of queries with data
(which is an assumption we already used for simple equality clauses).
This applies also to ALL clauses with an equality operator, which can be
considered equivalent to IN clause.

ALL clauses are still considered incompatible, although there's some
discussion about maybe relaxing this in the future.

Author: Pierre Ducroquet
Reviewed-by: Tomas Vondra, Dean Rasheed
Discussion: https://www.postgresql.org/message-id/flat/13902317.Eha0YfKkKy%40pierred-pdoc

This should of course be just "PG_ARGISNULL()".

Also reorder a couple of paras to make the discussion of PG_ARGISNULL
less disjointed.

Back-patch to v10 where the error was introduced.

Laurenz Albe and Tom Lane, per an anonymous docs comment

Discussion: https://postgr.es/m/158399487096.5708.10696365251766477013@wrigleys.postgresql.org

FOP issues warnings about them.  These aren't even used, so just
remove them.  For the ones that are actually used, we'll come up with
a different solution.

Discussion: https://www.postgresql.org/message-id/flat/e29b580e-79ab-a371-5ea4-6946e4d3af0b%402ndQuadrant.com

Use the new MyBackendType instead.  More similar changes for other "am
something" variables are possible.  This one was just particularly
simple.
Reviewed-by: Julien Rouhaud <rjuju123@gmail.com>
Reviewed-by: Kuntal Ghosh <kuntalghosh.2007@gmail.com>
Reviewed-by: Alvaro Herrera <alvherre@2ndquadrant.com>
Discussion: https://www.postgresql.org/message-id/flat/c65e5196-4f04-4ead-9353-6088c19615a3@2ndquadrant.com

Add a new global variable MyBackendType that uses the same BackendType
enum that was previously only used by the stats collector.  That way
several duplicate ways of checking what type a particular process is
can be simplified.  Since it's no longer just for stats, move to
miscinit.c and rename existing functions to match the expanded
purpose.
Reviewed-by: Julien Rouhaud <rjuju123@gmail.com>
Reviewed-by: Kuntal Ghosh <kuntalghosh.2007@gmail.com>
Reviewed-by: Alvaro Herrera <alvherre@2ndquadrant.com>
Discussion: https://www.postgresql.org/message-id/flat/c65e5196-4f04-4ead-9353-6088c19615a3@2ndquadrant.com

If an index was explicitly set as replica identity index, this setting
was lost when a table was rewritten by ALTER TABLE.  Because this
setting is part of pg_index but actually controlled by ALTER
TABLE (not part of CREATE INDEX, say), we have to do some extra work
to restore it.
Based-on-patch-by: Quan Zongliang <quanzongliang@gmail.com>
Reviewed-by: Euler Taveira <euler.taveira@2ndquadrant.com>
Discussion: https://www.postgresql.org/message-id/flat/c70fcab2-4866-0d9f-1d01-e75e189db342@gmail.com

This commit refactors and simplifies the definitions of StaticAssertStmt,
StaticAssertExpr and StaticAssertDecl.  By unifying the C and C++
fallback implementations, this reduces the number of different
implementations from four to three.

Author: Michael Paquier
Reviewed-by: Georgios Kokolatos, Tom Lane
Discussion: https://postgr.es/m/20200204081503.GF2287@paquier.xyz