estimate_path_cost_size() failed to re-use cached costs when the cached
startup/total cost was 0, so it calculated the costs redundantly.

This is an oversight in commit aa09cd24; but apply the patch to HEAD
only because there are no reports of actual trouble from that.

Author: Etsuro Fujita
Discussion: https://postgr.es/m/5C4AF3F3.4060409%40lab.ntt.co.jp

vacuumdb would use a catalog query only when the command caller does not
define a list of tables.  Switching to a catalog table represents two
advantages:
- Relation existence check can happen before running any VACUUM or
ANALYZE query.  Before this change, if multiple relations are defined
using --table, the utility would fail only after processing the
firstly-defined ones, which may be a long some depending on the size of
the relation.  This adds checks for the relation names, and does
nothing, at least yet, for the attribute names.
- More filtering options can become available for the utility user.
These options, which may be introduced later on, are based on the
relation size or the relation age, and need to be made available even if
the user does not list any specific table with --table.

Author: Nathan Bossart
Reviewed-by: Michael Paquier, Masahiko Sawada
Discussion: https://postgr.es/m/FFE5373C-E26A-495B-B5C8-911EC4A41C5E@amazon.com

Previously llvmjit.h #error'ed when USE_LLVM was not defined, to
prevent it from being included from code not having #ifdef USE_LLVM
guards - but that's not actually that useful after, during the
development of JIT support, LLVM related code was moved into a
separately compiled .so.  Having that #error means cpluspluscheck
doesn't work when llvm support isn't enabled, which isn't great.

Similarly add USE_LLVM guards to llvmjit_emit.h, and additionally make
sure it compiles standalone.

Per complaint from Tom Lane.

Author: Andres Freund
Discussion: https://postgr.es/m/19808.1548692361@sss.pgh.pa.us
Backpatch: 11, where JIT support was added

This reverts commit fc02e672 and
e6799d5a.

Parts of the buildfarm error out with
ERROR: page %u of relation "%s" should be empty but is not
errors, and so far I/we do not know why. fc02e672 didn't fix the
issue.  As I cannot reproduce the issue locally, it seems best to get
the buildfarm green again, and reproduce the issue without time
pressure.

In e6799d5a I removed vacuumlazy.c trickery around re-checking
whether a page is actually empty after acquiring an extension lock on
the relation, because the page is not PageInit()ed anymore, and
entries in the FSM ought not to lead to user-visible errors.

As reported by various buildfarm animals that is not correct, given
the way to code currently stands: If vacuum processes a page that's
just been newly added by either RelationGetBufferForTuple() or
RelationAddExtraBlocks(), it could add that page to the FSM and it
could be reused by other backends, before those two functions check
whether the newly added page is actually new.  That's a relatively
narrow race, but several buildfarm machines appear to be able to hit
it.

While it seems wrong that the FSM, given it's lack of durability and
approximative nature, can trigger errors like this, that seems better
fixed in a separate commit. Especially given that a good portion of
the buildfarm is red, and this is just re-introducing logic that
existed a few hours ago.

Author: Andres Freund
Discussion: https://postgr.es/m/20190128222259.zhi7ovzgtkft6em6@alap3.anarazel.de

In batching mode, COPY was using the same (per-tuple) memory context for
allocations with longer lifetime. This was confusing but harmless, until
commit 31f38174 added COPY FROM ... WHERE feature, introducing a risk
of memory leak.

The "per-tuple" memory context was reset only when starting new batch,
but as the rows may be filtered out by the WHERE clauses, that may not
happen at all.  The WHERE clause however has to be evaluated for all
rows, before filtering them out.

This commit separates the per-tuple and per-batch contexts, removing the
ambiguity.  Expressions (both defaults and WHERE clause) are evaluated
in the per-tuple context, while tuples are formed in the batch context.
This allows resetting the contexts at appropriate times.

The main complexity is related to partitioning, in which case we need to
reset the batch context after forming the tuple (which happens before
routing to leaf partition).  Instead of switching between two contexts
as before, we simply copy the last tuple aside, reset the context and
then copy the tuple back.  The performance impact is negligible, and
juggling with two contexts is not free either.

Discussion: https://www.postgresql.org/message-id/flat/CALAY4q_DdpWDuB5-Zyi-oTtO2uSk8pmy+dupiRe3AvAc++1imA@mail.gmail.com

The fact that "SELECT expression" has no base relations has long been a
thorn in the side of the planner.  It makes it hard to flatten a sub-query
that looks like that, or is a trivial VALUES() item, because the planner
generally uses relid sets to identify sub-relations, and such a sub-query
would have an empty relid set if we flattened it.  prepjointree.c contains
some baroque logic that works around this in certain special cases --- but
there is a much better answer.  We can replace an empty FROM clause with a
dummy RTE that acts like a table of one row and no columns, and then there
are no such corner cases to worry about.  Instead we need some logic to
get rid of useless dummy RTEs, but that's simpler and covers more cases
than what was there before.

For really trivial cases, where the query is just "SELECT expression" and
nothing else, there's a hazard that adding the extra RTE makes for a
noticeable slowdown; even though it's not much processing, there's not
that much for the planner to do overall.  However testing says that the
penalty is very small, close to the noise level.  In more complex queries,
this is able to find optimizations that we could not find before.

The new RTE type is called RTE_RESULT, since the "scan" plan type it
gives rise to is a Result node (the same plan we produced for a "SELECT
expression" query before).  To avoid confusion, rename the old ResultPath
path type to GroupResultPath, reflecting that it's only used in degenerate
grouping cases where we know the query produces just one grouped row.
(It wouldn't work to unify the two cases, because there are different
rules about where the associated quals live during query_planner.)

Note: although this touches readfuncs.c, I don't think a catversion
bump is required, because the added case can't occur in stored rules,
only plans.

Patch by me, reviewed by David Rowley and Mark Dilger

Discussion: https://postgr.es/m/15944.1521127664@sss.pgh.pa.us

There's no reason not to install these, and jit.h can be useful for
users of e.g. planner hooks.

Author: Donald Dong
Reviewed-By: Andres Freund
Discussion: https://postgr.es/m/296D405F-7F95-49F1-B565-389D6AA78505@csumb.edu
Backpatch: 11-, where JIT compilation was introduced

Previously we initialized pages when bulk extending in
RelationAddExtraBlocks(). That has a major disadvantage: It ties
RelationAddExtraBlocks() to heap, as other types of storage are likely
to need different amounts of special space, have different amount of
free space (previously determined by PageGetHeapFreeSpace()).

That we're relying on initializing pages, but not WAL logging the
initialization, also means the risk for getting
"WARNING:  relation \"%s\" page %u is uninitialized --- fixing"
style warnings in vacuums after crashes/immediate shutdowns, is
considerably higher. The warning sounds much more serious than what
they are.

Fix those two issues together by not initializing pages in
RelationAddExtraPages() (but continue to do so in
RelationGetBufferForTuple(), which is linked much more closely to
heap), and accepting uninitialized pages as normal in
vacuumlazy.c. When vacuumlazy encounters an empty page it now adds it
to the FSM, but does nothing else.  We chose to not issue a debug
message, much less a warning in that case - it seems rarely useful,
and quite likely to scare people unnecessarily.

For now empty pages aren't added to the VM, because standbys would not
re-discover such pages after a promotion. In contrast to other sources
for empty pages, there's no corresponding WAL records triggering FSM
updates during replay.

Author: Andres Freund
Reviewed-By: Tom Lane
Discussion: https://postgr.es/m/20181219083945.6khtgm36mivonhva@alap3.anarazel.de

This was used for the old CLUSTER syntax, has been unused since
e55c8e36.

Reviewed-by: Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>
Discussion: https://www.postgresql.org/message-id/flat/398754d8-6bb5-c5cf-e7b8-22e5f0983caf@2ndquadrant.com/

The completion here consists of attribute numbers, which is specific to
this grammar.

Author: Tatsuro Yamada
Reviewed-by: Peter Eisentraut
Discussion: https://portgr.es/m/b58a78fa-81ce-186f-f0bc-c1aa93c46cbf@lab.ntt.co.jp

This reverts commit ac88d296.

Previously, all heaps had FSMs. For very small tables, this means that the
FSM took up more space than the heap did. This is wasteful, so now we
refrain from creating the FSM for heaps with 4 pages or fewer. If the last
known target block has insufficient space, we still try to insert into some
other page before giving up and extending the relation, since doing
otherwise leads to table bloat. Testing showed that trying every page
penalized performance slightly, so we compromise and try every other page.
This way, we visit at most two pages. Any pages with wasted free space
become visible at next relation extension, so we still control table bloat.
As a bonus, directly attempting one or two pages can even be faster than
consulting the FSM would have been.

Once the FSM is created for a heap we don't remove it even if somebody
deletes all the rows from the corresponding relation.  We don't think it is
a useful optimization as it is quite likely that relation will again grow
to the same size.

Author: John Naylor with design inputs and some code contribution by Amit Kapila
Reviewed-by: Amit Kapila
Tested-by: Mithun C Y
Discussion: https://www.postgresql.org/message-id/CAJVSVGWvB13PzpbLEecFuGFc5V2fsO736BsdTakPiPAcdMM5tQ@mail.gmail.com

exist.

In commit's b9d01fe2 and 3908473c, we have added some code where we
allowed the creation of files during mdopen even if they didn't exist
during the bootstrap mode.  The later commit obviates the need for same.

This was harmless code till now but with an upcoming feature where we don't
allow to create FSM for small tables, this will needlessly create FSM
files.

Author: John Naylor
Reviewed-by: Amit Kapila
Discussion: https://www.postgresql.org/message-id/CAJVSVGWvB13PzpbLEecFuGFc5V2fsO736BsdTakPiPAcdMM5tQ@mail.gmail.com
	    https://www.postgresql.org/message-id/CAA4eK1KsET6sotf+rzOTQfb83pzVEzVhbQi1nxGFYVstVWXUGw@mail.gmail.com

vacuumdb generates by itself SQL queries to run ANALYZE or VACUUM on the
backend, but we never actually checked for query patterns with column
lists defined.

Author: Michael Paquier
Reviewed-by: Nathan Bossart
Discussion: https://postgr.es/m/FFE5373C-E26A-495B-B5C8-911EC4A41C5E@amazon.com

Given the right timing, psql could emit "connection to server was lost"
rather than one of the other messages that this test script checked for.
It looks like commit 4247db62 may have made this more likely, but
I don't really believe it was impossible before then.  Rather than
stress about it, just add that spelling as one of the crash-successfully-
detected cases.

Discussion: https://postgr.es/m/19344.1548554028@sss.pgh.pa.us

Before this change FunctionCallInfoData, the struct arguments etc for
V1 function calls are stored in, always had space for
FUNC_MAX_ARGS/100 arguments, storing datums and their nullness in two
arrays.  For nearly every function call 100 arguments is far more than
needed, therefore wasting memory. Arg and argnull being two separate
arrays also guarantees that to access a single argument, two
cachelines have to be touched.

Change the layout so there's a single variable-length array with pairs
of value / isnull. That drastically reduces memory consumption for
most function calls (on x86-64 a two argument function now uses
64bytes, previously 936 bytes), and makes it very likely that argument
value and its nullness are on the same cacheline.

Arguments are stored in a new NullableDatum struct, which, due to
padding, needs more memory per argument than before. But as usually
far fewer arguments are stored, and individual arguments are cheaper
to access, that's still a clear win.  It's likely that there's other
places where conversion to NullableDatum arrays would make sense,
e.g. TupleTableSlots, but that's for another commit.

Because the function call information is now variable-length
allocations have to take the number of arguments into account. For
heap allocations that can be done with SizeForFunctionCallInfoData(),
for on-stack allocations there's a new LOCAL_FCINFO(name, nargs) macro
that helps to allocate an appropriately sized and aligned variable.

Some places with stack allocation function call information don't know
the number of arguments at compile time, and currently variably sized
stack allocations aren't allowed in postgres. Therefore allow for
FUNC_MAX_ARGS space in these cases. They're not that common, so for
now that seems acceptable.

Because of the need to allocate FunctionCallInfo of the appropriate
size, older extensions may need to update their code. To avoid subtle
breakages, the FunctionCallInfoData struct has been renamed to
FunctionCallInfoBaseData. Most code only references FunctionCallInfo,
so that shouldn't cause much collateral damage.

This change is also a prerequisite for more efficient expression JIT
compilation (by allocating the function call information on the stack,
allowing LLVM to optimize it away); previously the size of the call
information caused problems inside LLVM's optimizer.

Author: Andres Freund
Reviewed-By: Tom Lane
Discussion: https://postgr.es/m/20180605172952.x34m5uz6ju6enaem@alap3.anarazel.de

Previously, \g would successfully execute the COPY command, but
the target specification if any was ignored, so that the data was
always dumped to the regular query output target.  This seems like
a clear bug, so let's not just fix it but back-patch it.

While at it, adjust the documentation for \copy to recommend
"COPY ... TO STDOUT \g foo" as a plausible alternative.

Back-patch to 9.5.  The problem exists much further back, but the
code associated with \g was refactored enough in 9.5 that we'd
need a significantly different patch for 9.4, and it doesn't
seem worth the trouble.

Daniel Vérité, reviewed by Fabien Coelho

Discussion: https://postgr.es/m/15dadc39-e050-4d46-956b-dcc4ed098753@manitou-mail.org

In some locales, letters sort before numbers, so change the object
naming to not depend on that.  Introduced by commit
7c079d74.

Since LISTEN is (still) disallowed, UNLISTEN must be a no-op in a
hot-standby session, and so there's no harm in allowing it.  This
change allows client code to not worry about whether it's connected
to a primary or standby server when performing session-state-reset
type activities.  (Note that DISCARD ALL, which includes UNLISTEN,
was already allowed, making it inconsistent to reject UNLISTEN.)

Per discussion, back-patch to all supported versions.

Shay Rojansky, reviewed by Mi Tar

Discussion: https://postgr.es/m/CADT4RqCf2gA_TJtPAjnGzkC3ZiexfBZiLmA-mV66e4UyuVv8bA@mail.gmail.com

There were two flags used to track the access to temporary tables and
to the temporary namespace of a session which are used to restrict
PREPARE TRANSACTION, however the first control flag is a concept
included in the second.  This removes the flag for temporary table
tracking, keeping around only the one at namespace level.

Author: Michael Paquier
Reviewed-by: Álvaro Herrera
Discussion: https://postgr.es/m/20190118053126.GH1883@paquier.xyz

Reported-by: Daniel Gustafsson

Discussion: https://postgr.es/m/431D5BC1-9696-43FA-B54C-39D5503EB753@yesql.se

Backpatch-through: master

This change allows callers of query_tree_walker() to choose whether
to visit an RTE before or after visiting the contents of the RTE
(i.e., prefix or postfix tree order).  All existing users of
QTW_EXAMINE_RTES want the QTW_EXAMINE_RTES_BEFORE behavior, but
an upcoming patch will want QTW_EXAMINE_RTES_AFTER, and it seems
like a potentially useful change on its own.

Andreas Karlsson (extracted from CTE inlining patch)

Discussion: https://postgr.es/m/8810.1542402910@sss.pgh.pa.us

While it's perhaps unlikely that users would write an explicit test
like "ctid IS NULL", this function is also used in range estimation,
and an incorrect answer can throw off the results for tight ranges.
Anyway it's not much code so we might as well do it.

Edmund Horner

Discussion: https://postgr.es/m/CAMyN-kCa3BFUFrCTtQeprxTU1anCd3Pua7zXstGCKq4pXgjukw@mail.gmail.com

Heikki's compiler doesn't complain about end_ptr, apparently,
but mine does.

In passing, I failed to resist the temptation to remove the
no-longer-used fldnum variable, and relocate chunk_len's
declaration to a narrower scope.

The old implementation first converted the input strings to arrays of
wchars, and performed the conversion on those. However, the conversion is
expensive, and for a large input string, consumes a lot of memory.
Allocating the large arrays also meant that these functions could not be
used on strings larger 1 GB / pg_encoding_max_length() (256 MB for UTF-8).

Avoid the conversion, and instead use the single-byte algorithm even with
multibyte encodings. That can get fooled, if there is a matching byte
sequence in the middle of a multi-byte character, so to eliminate false
positives like that, we verify any matches by walking the string character
by character with pg_mblen(). Also, if the caller needs the position of
the match, as a character-offset, we also need to walk the string to count
the characters.

Performance testing shows that walking the whole string with pg_mblen() is
somewhat slower than converting the whole string to wchars. It's still
often a win, though, because we don't need to do it if there is no match,
and even when there is, we only need to walk up to the point where the
match is, not the whole string. Even in the worst case, there would be
room for optimization: Much of the CPU time in the current loop with
pg_mblen() is function call overhead, and could be improved by inlining
pg_mblen() and/or the encoding-specific mblen() functions. But I didn't
attempt to do that as part of this patch.

Most of the callers of text_position_setup/next functions were actually
not interested in the position of the match, counted in characters. To
cater for them, refactor the text_position_next() interface into two
parts: searching for the next match (text_position_next()), and returning
the current match's position as a pointer (text_position_get_match_ptr())
or as a character offset (text_position_get_match_pos()). Getting the
pointer to the match is a more convenient API for many callers, and with
UTF-8, it allows skipping the character-walking step altogether, because
UTF-8 can't have false matches even when treated like raw byte strings.

Reviewed-by: John Naylor
Discussion: https://www.postgresql.org/message-id/3173d989-bc1c-fc8a-3b69-f24246f73876%40iki.fi

GB18030's mblen() function looks at the first and the second byte of the
multibyte character, to determine its length. copy.c had made the
assumption that mblen() only looks at the first byte, but it turns out to
work out fine, because of the way the GB18030 encoding works. COPY will
see a 4-byte encoded character as two 2-byte encoded characters, which is
enough for COPY's purposes. It cannot mix those up with delimiter or
escaping characters, because only single-byte ASCII characters are
supported as delimiters or escape characters.

Discussion: https://www.postgresql.org/message-id/7704d099-9643-2a55-fb0e-becd64400dcb%40iki.fi

Previously, only literals were allowed.  This change allows general
expressions, including functions calls, which are evaluated at the
time the DDL command is executed.

Besides offering some more functionality, it simplifies the parser
structures and removes some inconsistencies in how the literals were
handled.

Author: Kyotaro Horiguchi, Tom Lane, Amit Langote
Reviewed-by: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Discussion: https://www.postgresql.org/message-id/flat/9f88b5e0-6da2-5227-20d0-0d7012beaa1c@lab.ntt.co.jp/

This essentially reverts commits a772624b and 04fbe0e4, which
added "_configthreadlocale(_ENABLE_PER_THREAD_LOCALE)" calls to the
thread-related ecpg test programs.  That was nothing but a hack,
because we shouldn't expect that ecpg-using applications have
done that for us; and now that we've inserted such calls into
ecpglib, the tests should still pass without it.

(If they don't, it would be good to know that.)

HEAD only; there seems no big need to change this in the
back branches.

Discussion: https://postgr.es/m/22937.1548307384@sss.pgh.pa.us

A report from Andrew Dunstan showed that an ecpglib breakage that
causes repeated query failures could lead to infinite loops in some
ecpg test scripts, because they contain "while(1)" loops with no
exit condition other than successful test completion.  That might
be all right for manual testing, but it seems entirely unacceptable
for automated test environments such as our buildfarm.  We don't
want buildfarm owners to have to intervene manually when a test
goes wrong.

To fix, just change all those while(1) loops to exit after at most
100 iterations (which is more than any of them expect to iterate).
This seems sufficient since we'd see discrepancies in the test output
if any loop executed the wrong number of times.

I tested this by dint of intentionally breaking ecpg_do_prologue
to always fail, and verifying that the tests still got to completion.

Back-patch to all supported branches, since the whole point of this
exercise is to protect the buildfarm against future mistakes.

Discussion: https://postgr.es/m/18693.1548302004@sss.pgh.pa.us

This can be used by a profiler as the index for an array of
per-statement metrics.

Author: Pavel Stehule <pavel.stehule@gmail.com>
Reviewed-by: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Discussion: https://www.postgresql.org/message-id/flat/CAFj8pRDRCjN6rpM9ZccU7Ta_afsNX7mg9=n34F+r445Nt9v2tA@mail.gmail.com/

We were failing to set conislocal correctly for constraints in
partitions after partition detach, leading to those constraints becoming
undroppable.  Fix by setting the flag correctly.  Existing databases
might contain constraints with the conislocal wrongly set to false, for
partitions that were detached; this situation should be fixable by
applying an UPDATE on pg_constraint to set conislocal true.  This
problem should otherwise be innocuous and should disappear across a
dump/restore or pg_upgrade.

Secondarily, when constraint drop was attempted in a partitioned table,
ATExecDropConstraint would try to recurse to partitions after doing
performDeletion() of the constraint in the partitioned table itself; but
since the constraint in the partitions are dropped by the initial call
of performDeletion() (because of following dependencies), the recursion
step would fail since it would not find the constraint, causing the
whole operation to fail.  Fix by preventing recursion.

Reported-by: Amit Langote
Diagnosed-by: Amit Langote
Author: Amit Langote, Álvaro Herrera
Discussion: https://postgr.es/m/f2b8ead5-4131-d5a8-8016-2ea0a31250af@lab.ntt.co.jp

The pgbench regression test supposed that srandom() with a specific value
would result in deterministic output from random(), as required by POSIX.
It emerges however that OpenBSD is too smart to be constrained by mere
standards, so their random() emits nondeterministic output anyway.
While a workaround does exist, what seems like a better fix is to stop
relying on the platform's srandom()/random() altogether, so that what
you get from --random-seed=N is not merely deterministic but platform
independent.  Hence, use a separate pg_jrand48() random sequence in
place of random().

Also adjust the regression test case that's supposed to detect
nondeterminism so that it's more likely to detect it; the original
choice of random_zipfian parameter tended to produce the same output
all the time even if the underlying behavior wasn't deterministic.

In passing, improve pgbench's docs about random_zipfian().

Back-patch to v11 where this code was introduced.

Fabien Coelho and Tom Lane

Discussion: https://postgr.es/m/4615.1547792324@sss.pgh.pa.us

The original coding was too baroque and led to an use-after-release
mistake, noticed by buildfarm member prion.

Discussion: https://postgr.es/m/21693.1548305934@sss.pgh.pa.us

Previously, estimate_path_cost_size() didn't account for tlist eval
costs, except when costing a foreign-grouping path using local
statistics, but such costs should be accounted for when costing that path
using remote estimates, because some of the tlist expressions might be
evaluated locally.  Also, such costs should be accounted for in the case
of a foreign-scan or foreign-join path, because the tlist might contain
PlaceHolderVars, which postgres_fdw currently evaluates locally.

This also fixes an oversight in my commit f8f6e446.

Like that commit, apply this to HEAD only to avoid destabilizing existing
plan choices.

Author: Etsuro Fujita
Discussion: https://postgr.es/m/5BFD3EAD.2060301%40lab.ntt.co.jp

Apparently, some builds of MinGW contain a version of
_configthreadlocale() that always returns -1, indicating failure.
Rather than treating that as a curl-up-and-die condition, soldier on
as though the function didn't exist.  This leaves us without thread
safety on such MinGW versions, but we didn't have it anyway.

Discussion: https://postgr.es/m/d06a16bc-52d6-9f0d-2379-21242d7dbe81@2ndQuadrant.com

I (Álvaro) forgot to do this in eb7ed3f3, leading to undroppable
constraints after partitions are detached.  Repair.

Reported-by: Amit Langote
Author: Amit Langote
Discussion: https://postgr.es/m/c1c9b688-b886-84f7-4048-1e4ebe9b1d06@lab.ntt.co.jp

The flag was introduced in 3fdeb189, but f66e8bf8 actually forgot to
finish the cleanup as index_update_stats() has simplified its
interface.

Author: Michael Paquier
Discussion: https://postgr.es/m/20190122080852.GB3873@paquier.xyz