In combination with 569174f1, which
taught the btree AM how to perform parallel index scans, this allows
parallel index scan plans on btree indexes.  This infrastructure
should be general enough to support parallel index scans for other
index AMs as well, if someone updates them to support parallel
scans.

Amit Kapila, reviewed and tested by Anastasia Lubennikova, Tushar
Ahuja, and Haribabu Kommi, and me.

When min_parallel_relation_size was added, the only supported type
of parallel scan was a parallel sequential scan, but there are
pending patches for parallel index scan, parallel index-only scan,
and parallel bitmap heap scan.  Those patches introduce two new
types of complications: first, what's relevant is not really the
total size of the relation but the portion of it that we will scan;
and second, index pages and heap pages shouldn't necessarily be
treated in exactly the same way.  Typically, the number of index
pages will be quite small, but that doesn't necessarily mean that
a parallel index scan can't pay off.

Therefore, we introduce min_parallel_table_scan_size, which works
out a degree of parallelism for scans based on the number of table
pages that will be scanned (and which is therefore equivalent to
min_parallel_relation_size for parallel sequential scans) and also
min_parallel_index_scan_size which can be used to work out a degree
of parallelism based on the number of index pages that will be
scanned.

Amit Kapila and Robert Haas

Discussion: http://postgr.es/m/CAA4eK1KowGSYYVpd2qPpaPPA5R90r++QwDFbrRECTE9H_HvpOg@mail.gmail.com
Discussion: http://postgr.es/m/CAA4eK1+TnM4pXQbvn7OXqam+k_HZqb0ROZUMxOiL6DWJYCyYow@mail.gmail.com

This technically should involve a catversion bump, but that seems
pedantic, so I skipped it.

Report and patch by David Christensen.

I didn't realize these would ever be visible to clients, but Michael
figured out that it can happen when using asynchronous interfaces
such as PQconnectPoll.

Michael Paquier

Otherwise, the leftover empty result can cause problems in some
situations.

Michael Paquier and Ashutosh Bapat, per a report from Higuchi Daisuke

Reviewed-by: Magnus Hagander <magnus@hagander.net>

Commit 85c11324 renamed pg_resetxlog
to pg_resetwal, but didn't make pg_upgrade smart enough to cope with
the situation.

Michael Paquier, per a complaint from Jeff Janes

The core of the functionality was already implemented when
pg_import_system_collations was added.  This just exposes it as an
option in the SQL command.

Ashutosh Bapat

This isn't exposed to the optimizer or the executor yet; we'll add
support for those things in a separate patch.  But this puts the
basic mechanism in place: several processes can attach to a parallel
btree index scan, and each one will get a subset of the tuples that
would have been produced by a non-parallel scan.  Each index page
becomes the responsibility of a single worker, which then returns
all of the TIDs on that page.

Rahila Syed, Amit Kapila, Robert Haas, reviewed and tested by
Anastasia Lubennikova, Tushar Ahuja, and Haribabu Kommi.

Higuchi Daisuke

This doesn't do anything to make Param nodes anything other than
parallel-restricted, so this only helps with uncorrelated subplans,
and it's not necessarily very cheap because each worker will run the
subplan separately (just as a Hash Join will build a separate copy of
the hash table in each participating process), but it's a first step
toward supporting cases that are more likely to help in practice, and
is occasionally useful on its own.

Amit Kapila, reviewed and tested by Rafia Sabih, Dilip Kumar, and
me.

Discussion: http://postgr.es/m/CAA4eK1+e8Z45D2n+rnDMDYsVEb5iW7jqaCH_tvPMYau=1Rru9w@mail.gmail.com

The xlog-specific headers need to be included in both frontend code -
specifically, pg_waldump - and the backend, but the remainder of the
private headers for each index are only needed by the backend.  By
splitting the xlog stuff out into separate headers, pg_waldump pulls
in fewer backend headers, which is a good thing.

Patch by me, reviewed by Michael Paquier and Andres Freund, per a
complaint from Dilip Kumar.

Discussion: http://postgr.es/m/CA+TgmoZ=F=GkxV0YEv-A8tb+AEGy_Qa7GSiJ8deBKFATnzfEug@mail.gmail.com

Michael Paquier, reviewed and slightly revised by me.

Discussion: http://postgr.es/m/CAB7nPqRzCQb=vdfHvMtP0HMLBHU6z1aGdo4GJsUP-HP8jx+Pkw@mail.gmail.com

Range partitioning doesn't support nulls in the partitioning columns,
but list partitioning does.

Amit Langote, per a complaint from Amul Sul

I noticed while hacking on join UNION transforms that planner.c's
function get_base_rel_indexes() just duplicates the functionality of
get_relids_in_jointree().  It doesn't even have the excuse of being
older code :-(.  Drop it and use the latter function instead.

Commit 62e8b387 renamed "--xlog-method" option for pg_basebackup to
"--wal-method", but forgot to update the error message mentioning that option.

David Rowley, reviewed by Brad DeJong, Amit Kapila, and me.

Discussion: http://postgr.es/m/CAKJS1f81fob-M6RJyTVv3SCasxMuQpj37ReNOJ=tprhwd7hAVg@mail.gmail.com

Commit f82ec32a renamed the pg_xlog
directory to pg_wal. To make things consistent, we decided to eliminate
"xlog" from user-visible docs.

This module was intended to ease migrations of applications that used
the pre-8.3 version of text search to the in-core version introduced
in that release.  However, since all pre-8.3 releases of the database
have been out of support for more than 5 years at this point, we
expect that few people are depending on it at this point.  If some
people still need it, nothing prevents it from being maintained as a
separate extension, outside of core.

Discussion: http://postgr.es/m/CA+Tgmob5R8aDHiFRTQsSJbT1oreKg2FOSBrC=2f4tqEH3dOMAg@mail.gmail.com

The ALTER TABLE ALTER TYPE implementation can issue DROP INDEX and
CREATE INDEX to refit existing indexes for the new column type.  Since
this CREATE INDEX is an implementation detail of an index alteration,
the ensuing DefineIndex() should skip ACL checks specific to index
creation.  It already skips the namespace ACL check.  Make it skip the
tablespace ACL check, too.  Back-patch to 9.2 (all supported versions).

Reviewed by Tom Lane.

This stores a data type, required to be an integer type, with the
sequence.  The sequences min and max values default to the range
supported by the type, and they cannot be set to values exceeding that
range.  The internal implementation of the sequence is not affected.

Change the serial types to create sequences of the appropriate type.
This makes sure that the min and max values of the sequence for a serial
column match the range of values supported by the table column.  So the
sequence can no longer overflow the table column.

This also makes monitoring for sequence exhaustion/wraparound easier,
which currently requires various contortions to cross-reference the
sequences with the table columns they are used with.

This commit also effectively reverts the pg_sequence column reordering
in f3b421da, because the new seqtypid
column allows us to fill the hole in the struct and create a more
natural overall column ordering.
Reviewed-by: Steve Singer <steve@ssinger.info>
Reviewed-by: Michael Paquier <michael.paquier@gmail.com>

Add a section titled "Partitioned Tables" to describe what are
partitioned tables, partition, their similarities with inheritance.
The existing section on inheritance is retained for clarity.

Then add examples to the partitioning chapter that show syntax for
partitioned tables.  In fact they implement the same partitioning
scheme that is currently shown using inheritance.

Amit Langote, with additional details and explanatory text by me

Amit Langote

Amit Langote, with corrections by me

initdb and pg_basebackup now have a --waldir option rather --xlogdir,
and pg_basebackup now has --wal-method rather than --xlog-method.

xlog-switch becomes wal-switch, and xlog-insert becomes wal-insert.

This means pg_receivexlog because pg_receivewal, pg_resetxlog
becomes pg_resetwal, and pg_xlogdump becomes pg_waldump.

The S/390 members of the buildfarm are showing failures indicating
that they're having trouble with the rint() calls I added yesterday.
There's no good reason for that, and I wonder if it is a compiler bug
similar to the one we worked around in d9476b83.  Try to fix it using
the same method as before, namely to store the result of rint() back
into a "double" variable rather than immediately converting to int64.
(This isn't entirely waving a dead chicken, since on machines with
wider-than-double float registers, the extra store forces a width
conversion.  I don't know if S/390 is like that, but it seems worth
trying.)

In passing, merge duplicate ereport() calls in float8_timestamptz().

Per buildfarm.

Commit f82ec32a renamed the pg_xlog
directory to pg_wal.  To make things consistent, and because "xlog" is
terrible terminology for either "transaction log" or "write-ahead log"
rename all SQL-callable functions that contain "xlog" in the name to
instead contain "wal".  (Note that this may pose an upgrade hazard for
some users.)

Similarly, rename the xlog_position argument of the functions that
create slots to be called wal_position.

Discussion: https://www.postgresql.org/message-id/CA+Tgmob=YmA=H3DbW1YuOXnFVgBheRmyDkWcD9M8f=5bGWYEoQ@mail.gmail.com

Even if we don't emit definitions for SH_ALLOCATE and SH_FREE, we
still need prototypes.  The user can't define them before including
simplehash.h because SH_TYPE isn't available yet.

For the allocator to be able to access private_data, it needs to
become an argument to SH_CREATE.  Previously we relied on callers
to set that after returning from SH_CREATE, but SH_CREATE calls
SH_ALLOCATE before returning.

Dilip Kumar, reviewed by me.

Thomas Munro

It did that to verify that the page was an overflow page rather than
anything else, but that means that checking the status of all the
overflow bits requires reading the entire index.  So don't do that.
The new code validates that the page is not a primary bucket page
or bitmap page by looking at the metapage, so that using this on
large numbers of pages can be reasonably efficient.

Ashutosh Sharma, per a complaint from me, and with further
modifications by me.

It's always been possible for index AMs to cache data across successive
amgettuple calls within a single SQL command: the IndexScanDesc.opaque
field is meant for precisely that.  However, no comparable facility
exists for amortizing setup work across successive aminsert calls.
This patch adds such a feature and teaches GIN, GIST, and BRIN to use it
to amortize catalog lookups they'd previously been doing on every call.
(The other standard index AMs keep everything they need in the relcache,
so there's little to improve there.)

For GIN, the overall improvement in a statement that inserts many rows
can be as much as 10%, though it seems a bit less for the other two.
In addition, this makes a really significant difference in runtime
for CLOBBER_CACHE_ALWAYS tests, since in those builds the repeated
catalog lookups are vastly more expensive.

The reason this has been hard up to now is that the aminsert function is
not passed any useful place to cache per-statement data.  What I chose to
do is to add suitable fields to struct IndexInfo and pass that to aminsert.
That's not widening the index AM API very much because IndexInfo is already
within the ken of ambuild; in fact, by passing the same info to aminsert
as to ambuild, this is really removing an inconsistency in the AM API.

Discussion: https://postgr.es/m/27568.1486508680@sss.pgh.pa.us

A proposed patch, also by Thomas and in the same thread, would change
the output order of these.  Independent of the follow-up patches
getting committed, nailing down the order in these specific tests at
worst seems harmless.

Author: Thomas Munro
Discussion: https://postgr.es/m/CAEepm=1D4-tP7j7UAgT_j4ZX2j4Ehe1qgZQWFKBMb8F76UW5Rg@mail.gmail.com

When converting a float value to integer microseconds, we should be careful
to round the value to the nearest integer, typically with rint(); simply
assigning to an int64 variable will truncate, causing apparently off-by-one
values in cases that should work.  Most places in the datetime code got
this right, but not these two.

float8_timestamptz() is new as of commit e511d878 (9.6).  Previous
versions effectively depended on interval_mul() to do roundoff correctly,
which it does, so this fixes an accuracy regression in 9.6.

The problem in make_interval() dates to its introduction in 9.4.  Aside
from being careful to round not truncate, let's incorporate the hours and
minutes inputs into the result with exact integer arithmetic, rather than
risk introducing roundoff error where there need not have been any.

float8_timestamptz() problem reported by Erik Nordström, though this is
not his proposed patch.  make_interval() problem found by me.

Discussion: https://postgr.es/m/CAHuQZDS76jTYk3LydPbKpNfw9KbACmD=49dC4BrzHcfPv6yA1A@mail.gmail.com

When the new GUC wal_consistency_checking is set to a non-empty value,
it triggers recording of additional full-page images, which are
compared on the standby against the results of applying the WAL record
(without regard to those full-page images).  Allowable differences
such as hints are masked out, and the resulting pages are compared;
any difference results in a FATAL error on the standby.

Kuntal Ghosh, based on earlier patches by Michael Paquier and Heikki
Linnakangas.  Extensively reviewed and revised by Michael Paquier and
by me, with additional reviews and comments from Amit Kapila, Álvaro
Herrera, Simon Riggs, and Peter Eisentraut.

Add link to description of libpq connection strings.  Add link to
explanation of replication access control.  This currently points to the
description of streaming replication access control, which is currently
the same as for logical replication, but that might be refined later.
Also remove plain-text passwords from the examples, to not encourage
that dubious practice.

based on suggestions from Simon Riggs