For some reason, we have never accounted for either the evaluation cost
or the selectivity of filter conditions attached to Agg and Group nodes
(which, in practice, are always conditions from a HAVING clause).

Applying our regular selectivity logic to post-grouping conditions is a
bit bogus, but it's surely better than taking the selectivity as 1.0.
Perhaps someday the extended-statistics mechanism can be taught to provide
statistics that would help us in getting non-default estimates here.

Per a gripe from Benjamin Coutu.  This is surely a bug fix, but I'm
hesitant to back-patch because of the prospect of destabilizing existing
plan choices.  Given that it took us this long to notice the bug, it's
probably not hurting too many people in the field.

Discussion: https://postgr.es/m/20968.1509486337@sss.pgh.pa.us

It turns out we misdiagnosed what the real problem was.  Revert the
previous changes, because they may have worse consequences going
forward.  A better fix is forthcoming.

The simplistic test case is kept, though disabled.

Discussion: https://postgr.es/m/20171102112019.33wb7g5wp4zpjelu@alap3.anarazel.de

per request of the named person

Back-patch to v10.  This continues the work of commit
08035146.

Discussion: https://postgr.es/m/CAKOSWN=ds66zLw2SqkLTM8wbXFgDbc_OdkmT3dJfPT2mE5kipA@mail.gmail.com

Reported by Dan Vianello.

Discussion: https://postgr.es/m/e6e12f18f70e46848c058084d42fb651@KSTLMEXGP001.CORP.CHARTERCOM.com

If we don't have to return any columns from heap tuples, and there's
no need to recheck qual conditions, and the heap page is all-visible,
then we can skip fetching the heap page altogether.

Skip prefetching pages too, when possible, on the assumption that the
recheck flag will remain the same from one page to the next.  While that
assumption is hardly bulletproof, it seems like a good bet most of the
time, and better than prefetching pages we don't need.

This commit installs the executor infrastructure, but doesn't change
any planner cost estimates, thus possibly causing bitmap scans to
not be chosen in cases where this change renders them the best choice.
I (tgl) am not entirely convinced that we need to account for this
behavior in the planner, because I think typically the bitmap scan would
get chosen anyway if it's the best bet.  In any case the submitted patch
took way too many shortcuts, resulting in too many clearly-bad choices,
to be committable.

Alexander Kuzmenkov, reviewed by Alexey Chernyshov, and whacked around
rather heavily by me.

Discussion: https://postgr.es/m/239a8955-c0fc-f506-026d-c837e86c827b@postgrespro.ru

Also make the link to pg_stat_replication more precise.

Author: Michael Paquier <michael.paquier@gmail.com>
Reviewed-by: Jeff Janes <jeff.janes@gmail.com>

It's possible for dropping a column, or altering its type, to require
changes in domain CHECK constraint expressions; but the code was
previously only expecting to find dependent table CHECK constraints.
Make the necessary adjustments.

This is a fairly old oversight, but it's a lot easier to encounter
the problem in the context of domains over composite types than it
was before.  Given the lack of field complaints, I'm not going to
bother with a back-patch, though I'd be willing to reconsider that
decision if someone does complain.

Patch by me, reviewed by Michael Paquier

Discussion: https://postgr.es/m/30656.1509128130@sss.pgh.pa.us

Document the order of changing certain settings when using hot-standby
servers.  This is just a logical consequence of what was already
documented, but it gives the users some more practical advice.

Author: Yorick Peterse <yorickpeterse@gmail.com>
Reviewed-by: Aleksander Alekseev <a.alekseev@postgrespro.ru>
Reviewed-by: Robert Haas <robertmhaas@gmail.com>

A candidate path needs to be canonicalized before being checked against
the mappings, because the mappings are also canonicalized.  This is
especially relevant on Windows
Reported-by: nb <nbedxp@gmail.com>
Author: Michael Paquier <michael.paquier@gmail.com>
Reviewed-by: Ashutosh Sharma <ashu.coek88@gmail.com>

Informix mode.

Spotted and fixed by 高增琦 <pgf00a@gmail.com>

CREATE USER is an alias for CREATE ROLE, not its own command any longer,
so clean up references to the 'sql-createuser' link to go to
'sql-createrole' instead.

In passing, change a few cases of 'CREATE USER' to be
'CREATE ROLE ...  LOGIN'.  The remaining cases appear reasonable and
also mention the distinction between 'CREATE ROLE' and 'CREATE USER'.
Also, don't say CREATE USER "assumes" LOGIN, but rather "includes".

Patch-by: David G. Johnston, with assumes->includes by me.
Discussion: https://postgr.es/m/CAKFQuwYrbhKV8hH4TEABrDRBwf=gKremF=mLPQ6X2yGqxgFpYA@mail.gmail.com

Queries running with some non-pg_catalog schema frontmost in their search
path need to be careful to schema-qualify type names that should be sought
in pg_catalog.  Vitaly Burovoy reported an oversight of this sort in
pg_dump's dumpSequence, and grepping detected another one in psql's
describeOneTableDetails, both introduced by sequence-related changes in
v10.  In pg_dump, we can fix things by removing the cast altogether, since
it doesn't really matter what data types are reported for these query
result columns.  Likewise in psql, the query seemed to be working unduly
hard to get a result that's guaranteed to be exactly 'bigint'.

I also changed a couple of occurrences of "::char" similarly.  These are
not bugs, since "char" is a typename keyword and not subject to search_path
rules, but it seems better to use uniform style.

Vitaly Burovoy and Tom Lane

Discussion: https://postgr.es/m/CAKOSWN=ds66zLw2SqkLTM8wbXFgDbc_OdkmT3dJfPT2mE5kipA@mail.gmail.com

A read that returns zero bytes (or an error) should not increment
the number of temporary blocks read.

Thomas Munro

Discussion: http://postgr.es/m/CAEepm=21xgihg=WaG+O5MFotEZfN6kFETpfw+RkSnEqNQqGn2Q@mail.gmail.com

The entry in appinfo->translated_vars can be NULL; if so, we must avoid
dereferencing it.

Ashutosh Bapat

Discussion: http://postgr.es/m/CAFjFpReL7+1ien=-21rhjpO3bV7aAm1rQ8XgLVk2csFagSzpZQ@mail.gmail.com

Check that the values from pg_proc.h match what ProcedureCreate would
have done.

Robert Haas and Amul Sul

Discussion: http://postgr.es/m/CA+TgmoZ_UGXfq5ygeDDMdUSJ4J_VX7nFnjC6mfY6BgOJ3qZCmw@mail.gmail.com

The change made by commit 906bfcad means that if you're writing
a parenthesized column list in UPDATE ... SET, but that column list
is only one column, you now need to write ROW(expression) on the
righthand side, not just a parenthesized expression.  This was an
intentional change for spec compatibility and potential future
expansion of the possibilities for the RHS, but I'd neglected to
document it as a compatibility issue, figuring that hardly anyone
would bother with parenthesized syntax for a single target column.
I was wrong, as shown by questions from Justin Pryzby, Adam Brusselback,
and others.  Move the release note item into the compatibility section
and point out the behavior change for a single target column.

Discussion: https://postgr.es/m/CAMjNa7cDLzPcs0xnRpkvqmJ6Vb6G3EH8CYGp9ZBjXdpFfTz6dg@mail.gmail.com

In autovacuum's "work item" processing, a few strings were allocated in
the current transaction's memory context, which goes away during error
handling; if an error happened during execution of the work item, the
pfree() calls to clean up afterwards would try to release already-released
memory, possibly leading to a crash.  In branch master, this was already
fixed by commit 335f3d04, so backpatch that to REL_10_STABLE to fix
the problem there too.

As a secondary problem, verify that the autovacuum worker is connected
to the right database for each work item; otherwise some items would be
discarded by workers in other databases.

Reported-by: Justin Pryzby
Discussion: https://postgr.es/m/20171014035732.GB31726@telsasoft.com

Etsuro Fujita

Without this fix, dropping a role can sometimes result in parallel
query failures in sessions that have used "SET ROLE" to assume the
dropped role, even if that setting isn't active any more.

Report by Pavan Deolasee.  Patch by Amit Kapila, reviewed by me.

Discussion: http://postgr.es/m/CABOikdOomRcZsLsLK+Z+qENM1zxyaWnAvFh3MJZzZnnKiF+REg@mail.gmail.com

Michael Paquier, reviewed by Kuntal Ghosh and by me.  I did a little
wordsmithing on the documentation, too.

Discussion: http://postgr.es/m/CAB7nPqTuXuyEoVKcWcExh_b0uAjgWd_14KfGLrCTccBZ=VA0KA@mail.gmail.com

Extracted from a larger patch by Amul Sul, with some comment additions
by me.

Discussion: http://postgr.es/m/20171024113004.hn5qajypin4dy5sw@alap3.anarazel.de

In passing, don't insist on rsi->expectedDesc being set unless we
actually need it; this allows succeeding in a couple of cases where
PL/Perl functions returning setof composite would have failed before,
and makes the error message more apropos in other cases.

Discussion: https://postgr.es/m/4206.1499798337@sss.pgh.pa.us

Eiji Seki

Discussion: http://postgr.es/m/A11BD0E1A40FAC479D740CEFA373E203397E5276@g01jpexmbkw05

The previous comment (which was copied as boilerplate from one file
to the next) implied that it was the executor node itself which was
being serialized, but that's not right.  We're not serializing
the executor nodes; we're just allowing them to store some
additional information in DSM.  Adjusts the comment to reflect this.

Discussion: http://postgr.es/m/CA+TgmoaHVinxG=3h6qBAsyV8xaDyQwbzK7YZnYfE8nJFMK1=FA@mail.gmail.com

This is already present in the CREATE TABLE documentation, but it's
nicer not to have to refer to CREATE TABLE to find out the syntax
for ALTER TABLE.

Lætitia Avrot

Etsuro Fujita

Discussion: http://postgr.es/m/cc7767b6-6a1b-74a2-8b3c-48b8e64c12ed@lab.ntt.co.jp

Julien Rouhaud

Discussion: http://postgr.es/m/CAOBaU_Y4omLA+VbsVdA-JwBLoJWiPxfdKCkMjrZM7NMZxa1fKw@mail.gmail.com

Commit d5b760ec wasn't quite right, on second thought: if the
caller didn't ask for column names then it would happily emit
more Vars than if the caller did ask for column names.  This
is surely not a good idea.  Advance the aliasp_item whether or
not we're preparing a colnames list.

expandRTE() supposed that an RTE_SUBQUERY subquery must have exactly
as many non-junk tlist items as the RTE has column aliases for it.
This was true at the time the code was written, and is still true so
far as parse analysis is concerned --- but when the function is used
during planning, the subquery might have appeared through insertion
of a view that now has more columns than it did when the outer query
was parsed.  This results in a core dump if, for instance, we have
to expand a whole-row Var that references the subquery.

To avoid crashing, we can either stop expanding the RTE when we run
out of aliases, or invent new aliases for the added columns.  While
the latter might be more useful, the former is consistent with what
expandRTE() does for composite-returning functions in the RTE_FUNCTION
case, so it seems like we'd better do it that way.

Per bug #14876 from Samuel Horwitz.  This has been busted since commit
ff1ea217 allowed views to acquire more columns, so back-patch to all
supported branches.

Discussion: https://postgr.es/m/20171026184035.1471.82810@wrigleys.postgresql.org

This was always intended to work, but due to an oversight in
max_parallel_hazard_walker, it didn't.  In testing, we missed the
fact that it was only working for custom plans, where the parameter
value has been substituted for the parameter itself early enough
that everything worked.  In a generic plan, the Param node survives
and must be treated as parallel-safe.  SerializeParamList provides
for the transmission of parameter values to workers.

Amit Kapila with help from Kuntal Ghosh.  Some changes by me.

Discussion: http://postgr.es/m/CAA4eK1+_BuZrmVCeua5Eqnm4Co9DAXdM5HPAOE2J19ePbR912Q@mail.gmail.com

On closer investigation, commits f3ea3e3e et al were a few bricks
shy of a load.  What we need is not so much to lock down the result
type of a FieldSelect, as to lock down the existence of the column
it's trying to extract.  Otherwise, we can break it by dropping that
column.  The dependency on the result type is then held indirectly
through the column, and doesn't need to be recorded explicitly.

Out of paranoia, I left in the code to record a dependency on the
result type, but it's used only if we can't identify the pg_class OID
for the column.  That shouldn't ever happen right now, AFAICS, but
it seems possible that in future the input node could be marked as
being of type RECORD rather than some specific composite type.

Likewise for FieldStore.

Like the previous patch, back-patch to all supported branches.

Discussion: https://postgr.es/m/22571.1509064146@sss.pgh.pa.us

This reverts commit 94d622f2.  That
commit was supposed to get pushed to REL_10_STABLE, but I messed
up.

The NOTIFY page said this already, but the PREPARE TRANSACTION page
missed it.

Discussion: https://postgr.es/m/20171024010602.1488.80066@wrigleys.postgresql.org

Reduces ABI breakage.  Per Tom Lane.

Discussion: http://postgr.es/m/4035.1509113974@sss.pgh.pa.us

If we try to run a parallel plan in serial mode because, for example,
it's going to be scanned via a cursor, but for some reason we're
already in parallel mode (for example because an outer query is
running in parallel), we'd incorrectly try to launch workers.
Fix by adding a flag to the EState, so that we can be certain that
ExecutePlan() and ExecGather()/ExecGatherMerge() will have the same
idea about whether we are executing serially or in parallel.

Report and fix by Amit Kapila with help from Kuntal Ghosh.  A few
tweaks by me.

Discussion: http://postgr.es/m/CAA4eK1+_BuZrmVCeua5Eqnm4Co9DAXdM5HPAOE2J19ePbR912Q@mail.gmail.com

Since PL/Tcl does little with SQL types internally, this is just a
matter of making it work with composite-domain function arguments
and results.

In passing, make it allow RECORD-type arguments --- that's a trivial
change that nobody had bothered with up to now.

Discussion: https://postgr.es/m/4206.1499798337@sss.pgh.pa.us

This is the last major omission in our domains feature: you can now
make a domain over anything that's not a pseudotype.

The major complication from an implementation standpoint is that places
that might be creating tuples of a domain type now need to be prepared
to apply domain_check().  It seems better that unprepared code fail
with an error like "<type> is not composite" than that it silently fail
to apply domain constraints.  Therefore, relevant infrastructure like
get_func_result_type() and lookup_rowtype_tupdesc() has been adjusted
to treat domain-over-composite as a distinct case that unprepared code
won't recognize, rather than just transparently treating it the same
as plain composite.  This isn't a 100% solution to the possibility of
overlooked domain checks, but it catches most places.

In passing, improve typcache.c's support for domains (it can now cache
the identity of a domain's base type), and rewrite the argument handling
logic in jsonfuncs.c's populate_record[set]_worker to reduce duplicative
per-call lookups.

I believe this is code-complete so far as the core and contrib code go.
The PLs need varying amounts of work, which will be tackled in followup
patches.

Discussion: https://postgr.es/m/4206.1499798337@sss.pgh.pa.us

Previously, we skipped using search_indexed_tlist_for_sortgroupref()
if the tlist expression being sought in the child plan node was merely
a Var.  This is purely an optimization, based on the theory that
search_indexed_tlist_for_var() is faster, and one copy of a Var should
be as good as another.  However, the GROUPING SETS patch broke the
latter assumption: grouping columns containing the "same" Var can
sometimes have different outputs, as shown in the test case added here.
So do it the hard way whenever a ressortgroupref marking exists.

(If this seems like a bottleneck, we could imagine building a tlist index
data structure for ressortgroupref values, as we do for Vars.  But I'll
let that idea go until there's some evidence it's worthwhile.)

Back-patch to 9.6.  The problem also exists in 9.5 where GROUPING SETS
came in, but this patch is insufficient to resolve the problem in 9.5:
there is some obscure dependency on the upper-planner-pathification
work that happened in 9.6.  Given that this is such a weird corner case,
and no end users have complained about it, it doesn't seem worth the work
to develop a fix for 9.5.

Patch by me, per a report from Heikki Linnakangas.  (This does not fix
Heikki's original complaint, just the follow-on one.)

Discussion: https://postgr.es/m/aefc657e-edb2-64d5-6df1-a0828f6e9104@iki.fi