Previously this information was computed when JIT compiling an
expression.  But the information is useful for assertions in the
non-JIT case too (for assertions), therefore it makes sense to move
it.

This will, in a followup commit, allow to treat different slot types
differently. E.g. for virtual slots there's no need to generate a JIT
function to deform the slot.

Author: Andres Freund
Discussion: https://postgr.es/m/20181105210039.hh4vvi4vwoq5ba2q@alap3.anarazel.de

Upcoming work intends to allow pluggable ways to introduce new ways of
storing table data. Accessing those table access methods from the
executor requires TupleTableSlots to be carry tuples in the native
format of such storage methods; otherwise there'll be a significant
conversion overhead.

Different access methods will require different data to store tuples
efficiently (just like virtual, minimal, heap already require fields
in TupleTableSlot). To allow that without requiring additional pointer
indirections, we want to have different structs (embedding
TupleTableSlot) for different types of slots.  Thus different types of
slots are needed, which requires adapting creators of slots.

The slot that most efficiently can represent a type of tuple in an
executor node will often depend on the type of slot a child node
uses. Therefore we need to track the type of slot is returned by
nodes, so parent slots can create slots based on that.

Relatedly, JIT compilation of tuple deforming needs to know which type
of slot a certain expression refers to, so it can create an
appropriate deforming function for the type of tuple in the slot.

But not all nodes will only return one type of slot, e.g. an append
node will potentially return different types of slots for each of its
subplans.

Therefore add function that allows to query the type of a node's
result slot, and whether it'll always be the same type (whether it's
fixed). This can be queried using ExecGetResultSlotOps().

The scan, result, inner, outer type of slots are automatically
inferred from ExecInitScanTupleSlot(), ExecInitResultSlot(),
left/right subtrees respectively. If that's not correct for a node,
that can be overwritten using new fields in PlanState.

This commit does not introduce the actually abstracted implementation
of different kind of TupleTableSlots, that will be left for a followup
commit.  The different types of slots introduced will, for now, still
use the same backing implementation.

While this already partially invalidates the big comment in
tuptable.h, it seems to make more sense to update it later, when the
different TupleTableSlot implementations actually exist.

Author: Ashutosh Bapat and Andres Freund, with changes by Amit Khandekar
Discussion: https://postgr.es/m/20181105210039.hh4vvi4vwoq5ba2q@alap3.anarazel.de

Previously materializing a slot always returned a HeapTuple. As
current work aims to reduce the reliance on HeapTuples (so other
storage systems can work efficiently), that needs to change. Thus
split the tasks of materializing a slot (i.e. making it independent
from the underlying storage / other memory contexts) from fetching a
HeapTuple from the slot.  For brevity, allow to fetch a HeapTuple from
a slot and materializing the slot at the same time, controlled by a
parameter.

For now some callers of ExecFetchSlotHeapTuple, with materialize =
true, expect that changes to the heap tuple will be reflected in the
underlying slot.  Those places will be adapted in due course, so while
not pretty, that's OK for now.

Also rename ExecFetchSlotTuple to ExecFetchSlotHeapTupleDatum and
ExecFetchSlotTupleDatum to ExecFetchSlotHeapTupleDatum, as it's likely
that future storage methods will need similar methods. There already
is ExecFetchSlotMinimalTuple, so the new names make the naming scheme
more coherent.

Author: Ashutosh Bapat and Andres Freund, with changes by Amit Khandekar
Discussion: https://postgr.es/m/20181105210039.hh4vvi4vwoq5ba2q@alap3.anarazel.de

It was not really that obvious that there's meant to be exactly 1 item
in the partexprs List for each zero-valued partattrs element.  Some
incorrect code using these fields was the cause of CVE-2018-1052, so
it's worthwhile to mention how they should be used in the comments.

Author: David Rowley <david.rowley@2ndquadrant.com>

The comments above the PartitionedRelPruneInfo struct incorrectly
document how subplan_map and subpart_map are indexed.  This seems to
have snuck in on 4e232364.

Author: David Rowley <david.rowley@2ndquadrant.com>

With run-time partition pruning, there is no longer necessarily an
executor node for each corresponding plan node.

Author: David Rowley <david.rowley@2ndquadrant.com>

The current pattern of reseting expressions both in
ExecProcessReturning() and ExecOnConflictUpdate() makes it harder than
necessary to reason about memory lifetimes.  It also requires
materializing slots unnecessarily, although this patch doesn't take
advantage of the fact that that's not necessary anymore.

Instead reset the expression context once for each input tuple.

Author: Ashutosh Bapat
Discussion: https://postgr.es/m/20181105210039.hh4vvi4vwoq5ba2q@alap3.anarazel.de

The reformat_dat_file.pl script, added by 372728b0, supported
all the necessary options to make it work in a VPATH build, but the
makefile invocations didn't take VPATH into account. Fix that.

Discussion: https://postgr.es/m/20181115185303.d2z7wonx23mdfvd3@alap3.anarazel.de
Backpatch: 11-, where 372728b0 was merged

ExecFindInitialMatchingSubPlans has to update the PartitionPruneState's
subplan mapping data to account for the removal of subplans it prunes.
However, that's only necessary if run-time pruning will also occur,
so we can skip it when that won't happen, which should result in not
needing to do the remapping in many cases.  (We now need it only when
some partitions are potentially startup-time prunable and others are
potentially run-time prunable, which seems like an unusual case.)

Also make some marginal performance improvements in the remapping
itself.  These will mainly win if most partitions got pruned by
the startup-time pruning, which is perhaps a debatable assumption
in this context.

Also fix some bogus comments, and rearrange code to marginally
reduce space consumption in the executor's query-lifespan context.

David Rowley, reviewed by Yoshikazu Imai

Discussion: https://postgr.es/m/CAKJS1f9+m6-di-zyy4B4AGn0y1B9F8UKDRigtBbNviXOkuyOpw@mail.gmail.com

These functions were not crystal clear about what their respective APIs
are.  Make an effort to improve that.

Emre's patch was correct AFAICT, but I (Álvaro) felt the need to improve
a few comments a bit more.  Any resulting errors are my own.

Per complaint from Coverity, Ning Yu, and Tom Lane.

Author: Emre Hasegeli, Álvaro Herrera
Reviewed-by: Tomas Vondra, Álvaro Herrera
Discussion: https://postgr.es/m/26769.1533090136@sss.pgh.pa.us

Commit 5373bc2a has added type for background workers but forgot to
update at one place in the documentation.

Reported-by: John Naylor
Author: John Naylor
Reviewed-by: Amit Kapila
Backpatch-through: 11
Discussion: https://postgr.es/m/CAJVSVGVmvgJ8Lq4WBxC3zV5wf0txdCqRSgkWVP+jaBF=HgWscA@mail.gmail.com

Per complaint from Tom Lane, don't chomp the timestamp at 32 bits, so we
can shift in some of its higher bits.

Discussion: https://postgr.es/m/14712.1542253115%40sss.pgh.pa.us

Commit 197e4af9 refactored the initialization of the libc random()
seed, but reduced the number of possible seeds values that could be
chosen in a given time period.  This negation of the effects of
commit 98c50656 was unintentional.  Replace with code that
shifts the fast moving timestamp bits left, similar to the original
algorithm (though not the previous float-tolerating coding, which
is no longer necessary).

Author: Thomas Munro
Reported-by: Noah Misch
Reviewed-by: Tom Lane
Discussion: https://postgr.es/m/20181112083358.GA1073796%40rfd.leadboat.com

BufFileSize() can't use off_t, because it's only 32 bits wide on
some systems.  BufFile objects can have many 1GB segments so the
total size can exceed 2^31.  The only known client of the function
is parallel CREATE INDEX, which was reported to fail when building
large indexes on Windows.

Though this is technically an ABI break on platforms with a 32 bit
off_t and we might normally avoid back-patching it, the function is
brand new and thus unlikely to have been discovered by extension
authors yet, and it's fairly thoroughly broken on those platforms
anyway, so just fix it.

Defect in 9da0cc35.  Bug #15460.  Back-patch to 11, where this
function landed.

Author: Thomas Munro
Reported-by: Paul van der Linden, Pavel Oskin
Reviewed-by: Peter Geoghegan
Discussion: https://postgr.es/m/15460-b6db80de822fa0ad%40postgresql.org
Discussion: https://postgr.es/m/CAHDGBJP_GsESbTt4P3FZA8kMUKuYxjg57XHF7NRBoKnR%3DCAR-g%40mail.gmail.com

The previous behavior of preferring the oldest match had the advantage
of not breaking existing scripts when we add a conflicting format name;
but that behavior was undocumented and fragile (it seems just luck that
commit add9182e didn't break it).  Let's go over to the less mistake-
prone approach of complaining when there are multiple matches.

Since this is a small compatibility break, no back-patch.

Daniel Vérité

Discussion: https://postgr.es/m/cb7e1caf-3ea6-450d-af28-f524903a030c@manitou-mail.org

This hasn't been correct since 9.3 added "latex-longtable".

I left the phraseology "Unique abbreviations are allowed" alone.
It's correct as far as it goes, and we are studiously refraining
from specifying exactly what happens if you give a non-unique
abbreviation.  (The answer in the back branches is "you get a
backwards-compatible choice", and the answer in HEAD will shortly
be "you get an error", but there seems no need to mention such
details here.)

Daniel Vérité

Discussion: https://postgr.es/m/cb7e1caf-3ea6-450d-af28-f524903a030c@manitou-mail.org

date_trunc(field, timestamptz, zone_name) performs truncation using
the named time zone as reference, rather than working in the session
time zone as is the default behavior.  It's equivalent to

date_trunc(field, timestamptz at time zone zone_name) at time zone zone_name

but it's faster, easier to type, and arguably easier to understand.

Vik Fearing and Tom Lane

Discussion: https://postgr.es/m/6249ffc4-2b22-4c1b-4e7d-7af84fedd7c6@2ndquadrant.com

In commit ecfd5579, I removed sqlda.c's checks for ndigits != 0 on the
grounds that we should duplicate the state of the numeric value's digit
buffer even when all the digits are zeroes.  However, that still isn't
quite right, because another possible state of the digit buffer is
buf == digits == NULL (this occurs for a NaN).  As the code now stands,
it'll invoke memcpy with a NULL source address and zero bytecount,
which we know a few platforms crash on.  Hence, reinstate the no-copy
short-circuit, but make it test specifically for buf != NULL rather than
some other condition.  In hindsight, the ndigits test (added by commit
f2ae9f9c) was almost certainly meant to fix the NaN case not the
all-zeroes case as the associated thread alleged.

As before, back-patch to all supported versions.

Discussion: https://postgr.es/m/1803D792815FC24D871C00D17AE95905C71161@g01jpexmbkw24

Change lock level for renaming index (either ALTER INDEX or implicitly
via some other commands) from AccessExclusiveLock to
ShareUpdateExclusiveLock.

One reason we need a strong lock for relation renaming is that the
name change causes a rebuild of the relcache entry.  Concurrent
sessions that have the relation open might not be able to handle the
relcache entry changing underneath them.  Therefore, we need to lock
the relation in a way that no one can have the relation open
concurrently.  But for indexes, the relcache handles reloads specially
in RelationReloadIndexInfo() in a way that keeps changes in the
relcache entry to a minimum.  As long as no one keeps pointers to
rd_amcache and rd_options around across possible relcache flushes,
which is the case, this ought to be safe.

We also want to use a self-exclusive lock for correctness, so that
concurrent DDL doesn't overwrite the rename if they start updating
while still seeing the old version.  Therefore, we use
ShareUpdateExclusiveLock, which is already used by other DDL commands
that want to operate in a concurrent manner.

The reason this is interesting at all is that renaming an index is a
typical part of a concurrent reindexing workflow (CREATE INDEX
CONCURRENTLY new + DROP INDEX CONCURRENTLY old + rename back).  And
indeed a future built-in REINDEX CONCURRENTLY might rely on the ability
to do concurrent renames as well.
Reviewed-by: Andrey Klychkov <aaklychkov@mail.ru>
Reviewed-by: Fabrízio de Royes Mello <fabriziomello@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/1531767486.432607658@f357.i.mail.ru

If a failure happens when a transaction is starting between the moment
the transaction status is changed from TRANS_DEFAULT to TRANS_START and
the moment the current user ID and security context flags are fetched
via GetUserIdAndSecContext(), or before initializing its basic fields,
then those may get reset to incorrect values when the transaction
aborts, leaving the session in an inconsistent state.

One problem reported is that failing a starting transaction at the first
query of a session could cause several kinds of system crashes on the
follow-up queries.

In order to solve that, move the initialization of the transaction state
fields and the call of GetUserIdAndSecContext() in charge of fetching
the current user ID close to the point where the transaction status is
switched to TRANS_START, where there cannot be any error triggered
in-between, per an idea of Tom Lane.  This properly ensures that the
current user ID, the security context flags and that the basic fields of
TransactionState remain consistent even if the transaction fails while
starting.

Reported-by: Richard Guo
Diagnosed-By: Richard Guo
Author: Michael Paquier
Reviewed-by: Tom Lane
Discussion: https://postgr.es/m/CAN_9JTxECSb=pEPcb0a8d+6J+bDcOZ4=DgRo_B7Y5gRHJUM=Rw@mail.gmail.com
Backpatch-through: 9.4

Hexadecimal is consistently used as format to not bloat too much the
output but keep it readable.  This information is useful mainly for
debugging purposes with for example pg_waldump.

Author: Michael Paquier
Reviewed-by: Nathan Bossart, Dmitry Dolgov, Andres Freund, Álvaro
Herrera
Discussion: https://postgr.es/m/20180413034734.GE1552@paquier.xyz

The code building PartitionBoundInfo based on the constituent partition
data read from catalogs has been located in partcache.c, with a specific
set of routines dedicated to bound types, like sorting or bound data
creation.  All this logic is moved to partbounds.c and relocates all the
bound-specific logistic into it, with partition_bounds_create() as
principal entry point.

Author: Amit Langote
Reviewed-by: Michael Paquier, Álvaro Herrera
Discussion: https://postgr.es/m/3f289da8-6d10-75fe-814a-635e8b191d43@lab.ntt.co.jp

This case was uncovered by existing tests, so breakage went undetected.
Make sure it remains stable.

Extracted from a larger patch by
Author: David Rowley
Reviewed-by: Amit Langote
Discussion: https://postgr.es/m/CAKJS1f-aGCJ5H7_hiSs5PhWs6Obmj+vGARjGymqH1=o5PcrNnQ@mail.gmail.com

Numeric values with leading zeroes were incorrectly copied into a
SQLDA (SQL Descriptor Area), leading to wrong results in ECPG programs.

Report and patch by Daisuke Higuchi.  Back-patch to all supported
versions.

Discussion: https://postgr.es/m/1803D792815FC24D871C00D17AE95905C71161@g01jpexmbkw24

The realfail1 and realfail2 backup-prevention rules always returned
token type FCONST, ignoring the possibility that what we've scanned
is more appropriately described as ICONST.  I think that at the
time that code was added, it might actually have been safe to not
distinguish; but since we started allowing AS-less aliases in SELECT
target lists, it's definitely legal to have a number immediately
followed by an identifier.

In the SELECT case, it seems there's no visible consequence because
make_const() will change the type back to integer anyway.  But I'm
worried that there are other contexts, or will be in future, where
it's more important to get the constant's type right.

Hence, use process_integer_literal to correctly determine which
token type to return.

Arguably this is a bug fix, but given the lack of evidence of
user-visible problems, I'll refrain from back-patching.

Discussion: https://postgr.es/m/21364.1542136808@sss.pgh.pa.us

scanner_init/scanner_finish weren't actually called from anywhere,
and the scanbuf variables they set up weren't used either.

Remove unused declaration for mm_realloc, too.

John Naylor

Discussion: https://postgr.es/m/CAJVSVGWGqY9YBs2EwtRUkbNv=hXkN8yRPOoD1wxE6COgvvrz5g@mail.gmail.com

Make a bunch of basically-cosmetic changes to reduce the diffs between
the flex rules in scan.l, psqlscan.l, and pgc.l.  Reorder some code,
adjust a lot of whitespace, sync some comments, make use of flex start
condition scopes to do that.

There are a few non-cosmetic changes in the ECPG lexer:

* Bring over the decimalfail rule (and support function
process_integer_literal) so that ECPG will lex "1..10" into
the same tokens as the backend would.  I'm not sure this makes any
visible difference to users, but I'm not sure it doesn't, either.

* <xdc><<EOF>> gets its own rule so as to produce a more on-point
error message.

* Remove duplicate <SQL>{xdstart} rule.

John Naylor, with a few additional changes by me

Discussion: https://postgr.es/m/CAJVSVGWGqY9YBs2EwtRUkbNv=hXkN8yRPOoD1wxE6COgvvrz5g@mail.gmail.com

Reported-by: David G. Johnston <david.g.johnston@gmail.com>

A table with OIDs that was the first in the dump output would not get
dumped with OIDs enabled.  Fix that.

The reason was that the currWithOids flag was declared to be bool but
actually also takes a -1 value for "don't know yet".  But under
stdbool.h semantics, that is coerced to true, so the required SET
default_with_oids command is not output again.  Change the variable
type to char to fix that.
Reported-by: Derek Nelson <derek@pipelinedb.com>

Per buildfarm.

group clearing mechanism.

Commits 0e141c0f and baaf272a introduced initialization of atomic
variables in InitProcess which means that it's not safe to look at those
for backends that aren't currently in use.  Fix that by initializing them
during postmaster startup.

Reported-by: Andres Freund
Author: Amit Kapila
Backpatch-through: 9.6
Discussion: https://postgr.es/m/20181027104138.qmbbelopvy7cw2qv@alap3.anarazel.de

Commit 35c0754f failed to handle space-separated lists of alternative
hostnames in ldapserver, when building a URI for ldap_initialize()
(OpenLDAP).  Such lists need to be expanded to space-separated URIs.

Repair.  Back-patch to 11, to fix bug report #15495.

Author: Thomas Munro
Reported-by: Renaud Navarro
Discussion: https://postgr.es/m/15495-2c39fc196c95cd72%40postgresql.org

Coverty reports a possible buffer overrun in the code that populates the
pg_hba_file_rules view.  It may not be a live bug due to restrictions
on options that can be used together, but let's increase MAX_HBA_OPTIONS
and correct a nearby misleading comment.

Back-patch to 10 where this code arrived.

Reported-by: Julian Hsiao
Discussion: https://postgr.es/m/CADnGQpzbkWdKS2YHNifwAvX5VEsJ5gW49U4o-7UL5pzyTv4vTg%40mail.gmail.com

This comes from f9b5b41e, which is part of one the original commits that
implemented ON COMMIT actions.  By looking at the truncation code, any
CCI needed happens locally when rebuilding indexes, so it looks safe to
just remove this final incrementation.

Author: Michael Paquier
Reviewed-by: Álvaro Herrera
Discussion: https://postgr.es/m/20181109024731.GF2652@paquier.xyz

There's no point in asking deconstruct_array() for a null-flags
array when we already checked the array has no nulls, and aren't
going to examine the output anyhow.  Not asking for this output
should make the code marginally faster, and it's also more
robust since if there somehow were nulls, deconstruct_array()
would throw an error.

Daniel Gustafsson

Discussion: https://postgr.es/m/289FFB8B-7AAB-48B5-A497-6E0D41D7BA47@yesql.se

classify_index_clause_usage() is O(N^2) in the number of distinct index
qual clauses it considers, because of its use of a simple search list to
store them.  For nearly all queries, that's fine because only a few clauses
will be considered.  But Alexander Kuzmenkov reported a machine-generated
query with 80000 (!) index qual clauses, which caused this code to take
forever.  Somewhat remarkably, this is the only O(N^2) behavior we now
have for such a query, so let's fix it.

We can get rid of the O(N^2) runtime for cases like this without much
damage to the functionality of choose_bitmap_and() by separating out
paths with "too many" qual or pred clauses, and deeming them to always
be nonredundant with other paths.  Then their clauses needn't go into
the search list, so it doesn't get too long, but we don't lose the
ability to consider bitmap AND plans altogether.  I set the threshold
for "too many" to be 100 clauses per path, which should be plenty to
ensure no change in planning behavior for normal queries.

There are other things we could do to make this go faster, but it's not
clear that it's worth any additional effort.  80000 qual clauses require
a whole lot of work in many other places, too.

The code's been like this for a long time, so back-patch to all supported
branches.  The troublesome query only works back to 9.5 (in 9.4 it fails
with stack overflow in the parser); so I'm not sure that fixing this in
9.4 has any real-world benefit, but perhaps it does.

Discussion: https://postgr.es/m/90c5bdfa-d633-dabe-9889-3cf3e1acd443@postgrespro.ru

Author: Alexander Lakhin
Discussion: https://postgr.es/m/2f55f6d2-3fb0-d4f6-5c47-18da3a1117e0@gmail.com

A note in ddl.sgml used to mention that run-time pruning was only
implemented for Append.  When we got MergeAppend support, this was
updated to mention that MergeAppend is supported too.  This is
slightly weird as it's not all that obvious what exactly isn't
supported when we mention:

    <para>
     Both of these behaviors are likely to be changed in a future release
     of <productname>PostgreSQL</productname>.
    </para>

This patch updates this to mention that ModifyTable is unsupported,
which makes the above fragment make sense again.

Author: David Rowley <david.rowley@2ndquadrant.com>

Discussion: https://postgr.es/m/05f348de-0c79-d88d-69b7-434ef828bd4d@2ndQuadrant.com