* docs - move gpmapreduce yaml info to own utility page; misc topic edits

* relocate topic and graphic, add shortdesc, fix linking

Earlier, COPY <Catalogtable> from <file> was allowed irrespective of the
value of allow_system_table_mods. This commit restricts such statements
only when allow_system_table_mods is set to ON.

Co-Authored-By: Ashwin Agrawal<aagrawal@pivotal.io>

This reverts commit 1db9b27a.

This is breaking a memory accounting test.

We introduce a new type of memory pool and memory pool manager:
CMemoryPoolPalloc and CMemoryPoolPallocManager

The motivation for this PR is to improve memory allocation/deallocation
performance when using GPDB allocators. Additionally, we would like to
use the GPDB memory allocators by default (change the default for
optimizer_use_gpdb_allocators to on), to prevent ORCA from crashing when
we run out of memory (OOM). However, with the current way of doing
things, doing so would add around 10 % performance overhead to ORCA.

CMemoryPoolPallocManager overrides the default CMemoryPoolManager in
ORCA, and instead creates a CMemoryPoolPalloc memory pool instead of a
CMemoryPoolTracker. In CMemoryPoolPalloc, we now call MemoryContextAlloc
and pfree instead of gp_malloc and gp_free, and we don’t do any memory
accounting.

So where does the performance improvement come from? Previously, we
would (essentially) pass in gp_malloc and gp_free to an underlying
allocation structure (which has been removed on the ORCA side). However,
we would add additional headers and overhead to maintain a list of all
of these allocations. When tearing down the memory pool, we would
iterate through the list of allocations and explicitly free each one. So
we would end up doing overhead on the ORCA side, AND the GPDB side.
However, the overhead on both sides was quite expensive!

If you want to compare against the previous implementation, see the
Allocate and Teardown functions in CMemoryPoolTracker.

With this PR, we improve optimization time by ~15% on average and up to
30-40% on some queries which are memory intensive.

This PR does remove memory accounting in ORCA. This was only enabled
when the optimizer_use_gpdb_allocators GUC was set. By setting
`optimizer_use_gpdb_allocators`, we still capture the memory used when
optimizing a query in ORCA, without the overhead of the memory
accounting framework.

Additionally, Add a top level ORCA context where new contexts are created

The OptimizerMemoryContext is initialized in InitPostgres(). For each
memory pool in ORCA, a new memory context is created in
OptimizerMemoryContext.

Bumps ORCA version to 3.74.0
Co-authored-by: NShreedhar Hardikar <shardikar@pivotal.io>
Co-authored-by: NChris Hajas <chajas@pivotal.io>

- as an experiment. We want to see if it becomes less flakey.

(cherry picked from commit b99920ff)

Otherwise it is necessary to always pass the flag set to 'no' for the package
builds. This commit completes <3827c3a6> regarding tab completion.
Reported-by: NBradford D. Boyle <bboyle@pivotal.io>
Reviewed-by: NBradford D. Boyle <bboyle@pivotal.io>
Reviewed-by: NXin Zhang <xzhang@pivotal.io>
(cherry picked from commit 15f80832)

When building gpdb with a non-empty DESTDIR, the build would fail
because certain Makefiles were not correctly account for it.
Additionally, when we make a symlink for `gpcheckcat` we *should not*
include DESTDIR in the target. A common usage for DESTDIR is to allow
moving the build artifacts after the build is completed. If the target
includes DESTDIR, than the link could point to a non-existing path.
Authored-by: NBradford D. Boyle <bboyle@pivotal.io>
(cherry picked from commit 7de35b7e)

* docs - add GUC optimizer_enable_dml

* docs - review comment updates. Add guc to table.

* docs - add optimizer_enable_dml GUC to ditamap

* docs - promote pxf protocol over s3 protocol

--Reordered listing of pxf and s3.
--Added link to pxf protocol from s3 protocol
--Updated some pxf/s3 information in g-external-tables.xml
 pxf uses CREATE EXTENSION, s3 uses CREATE PROTOCOL

* docs - updated ditamap - to put PXF first under "Working with External Data"

Corresponding ORCA commits:
* Refactor: Simplify property derivation in CExpression
* Support on-demand property derivation in CDrvdPropRelational
* Rename DrvdPropArray to DrvdProp and DrvdProp2dArray to DrvdPropArray
* Bump ORCA version to 3.73.0
Authored-by: NChris Hajas <chajas@pivotal.io>
(cherry picked from commit 043365cc)

* docs - Add note for gpfdist/gpload wrong line number in error messages

This will be backporrted to 6X_STABLE, 5X_STABLE, and 4.3.x

* docs - fixed typo

- otherwise the cluster remains running if a test fails, which is
  problematic for the next test run.

gp_tablespace_with_faults test writes no-op record and waits for
mirror to replay the same before deleting the tablespace
directories. This step fails sometime in CI and causes flaky
behavior. The is due to existing code behavior in startup and
walreceiver process. If primary writes big (means spanning across
multiple pages) xlog record, flushes only partial xlog record due to
XLogBackgroundFlush() but restarts before commiting the transaction,
mirror only receives partial record and waits to get complete
record. Meanwhile after recover, no-op record gets written in place of
that big record, startup process on mirror continues to wait to
receive xlog beyond previously received point to proceed further.

Hence, as temperory workaround till the actual code problem is not
resolved and to avoid failures for this test, switch xlog before
emitting no-op xlog record, to have no-op record at far distance from
previously emitted xlog record.

(cherry picked from commit efd76c4c)

- introduces test helpers to remove knowledge from the suite file.

If the number of rows is always passed around together with the actual
rows, there's a missing abstraction.

This eliminates the warning "incompatible pointer types" as in:

```
greenplum_five_to_greenplum_six_upgrade_test.c:137:23: warning: incompatible pointer types passing 'User *(*)[10]' to parameter of type 'User **' (aka 'struct UserData **') [-Wincompatible-pointer-types]
        initialize_user_rows(&rows, size);
                             ^~~~~
```

By declaring them static
```
greenplum_five_to_greenplum_six_upgrade_test.c:35:1: warning: no previous prototype for function 'connectToFive' [-Wmissing-prototypes]
connectToFive()
^
```

* Re-ordering Makefile.global and Makefile.mock brings in the
much-needed global CFLAGS that turn some warnings into errors
* Add missing headers to fix "missing prototype" errors
* While we're at it, properly use <> for system / standard headers

The cause of the PANIC was an incorrectly populated list containing the
namespace information for the affected the relation. A GrantStmt contains the
necessary objects in a list named objects. This gets initially populated during
parsing (via the privilege_target rule) and processed during parse analysis based
on the target type and object type to RangeVar nodes, FuncWithArgs nodes or
plain names.

In Greenplum, the catalog information about the partition hierarchies is not
propagated to all segments. This information needs to be processed in the
dispatcher and to be added backed in the parsed statement for the segments to
consume.

In this commit, the partition hierarchy information is expanded only for the
target and object type required. The parsed statement gets updated
uncoditionally of partitioned references before dispatching for required types.

The privileges tests have been updated to get check for privileges in the
segments also.

Problem identified and initial patch by Fenggang <ginobiliwang@gmail.com>,
reviewed and refactored by me.

(cherry picked from commit 7ba2af39)

Current code for COPY FROM picks mode as COPY_DISPATCH for
non-distributed/non-replicated table as well. This causes crash. It
should be using COPY_DIRECT, which is normal/direct mode to be used
for such tables.

The crash was exposed by following SQL commands:

    CREATE TABLE public.heap01 (a int, b int) distributed by (a);
    INSERT INTO public.heap01 VALUES (generate_series(0,99), generate_series(0,98));
    ANALYZE public.heap01;

    COPY (select * from pg_statistic where starelid = 'public.heap01'::regclass) TO '/tmp/heap01.stat';
    DELETE FROM pg_statistic where starelid = 'public.heap01'::regclass;
    COPY pg_statistic from '/tmp/heap01.stat';

Important note: Yes, it's known and strongly recommended to not touch
the `pg_statistics` or any other catalog table this way. But it's no
good to panic either. The copy to `pg_statictics` is going to ERROR
out "correctly" and not crash after this change with `cannot accept a
value of type anyarray`, as there just isn't any way at the SQL level
to insert data into pg_statistic's anyarray columns. Refer:
https://www.postgresql.org/message-id/12138.1277130186%40sss.pgh.pa.us

(cherry picked from commit 6793882b)

* docs - move install guide to gpdb repo

--move Install Guide source files back to gpdb repo.
--update config.yml and gpdb-landing-subnav.erb files for OSS doc builds.
--removed refs directory - unused utility reference pages.
--Also added more info to creating a gpadmin user.

These files have conditionalized text (pivotal and oss-only).

./supported-platforms.xml
./install_gpdb.xml
./apx_mgmt_utils.xml
./install_guide.ditamap
./preinstall_concepts.xml
./migrate.xml
./install_modules.xml
./prep_os.xml
./upgrading.xml

* docs - updated supported platforms with PXF information.

* docs - install guide review comment update

-- renamed one file from supported-platforms.xml to platform-requirements.xml

* docs - reworded requirement/warning based on review comments.

* add ad steps in pxf krb doc

* From Lisa Owen

* distributing keytab using gpscp and gpssh

* Update gpdb-doc/markdown/pxf/pxf_kerbhdfs.html.md.erb
Co-Authored-By: NAlexander Denissov <denalex@users.noreply.github.com>

* Update gpdb-doc/markdown/pxf/pxf_kerbhdfs.html.md.erb
Co-Authored-By: NAlexander Denissov <denalex@users.noreply.github.com>

* misc formatting edits

* a few more formatting edits