The user can adjust the ic-proxy peer addresses at runtime and reload by
sending SIGHUP, if an address is modified or removed, the corresponding
peer connection must be closed or reestablished.  The same to the peer
listener, if the listener port is changed, then must re-setup the
listener.

The peer addresses are specified with the GUC
gp_interconnect_proxy_addresses, it can be reloaded on SIGHUP, we used
to only care about the newly added ones, however it is also possible for
the user to modify them, or even remove some of them.

So now we add the logic to classify the addresses after parsing the GUC,
we can tell whether an address is added, removed, or modified.

The handling of the classified addresses will be done in the next
commit.

We used to scan the whole addr list to find my addr, now we record it
directly when parsing the addresses.

A ICProxyAddr variable is usually named as "addr", so the attribute is
referred as "addr->addr", it's confusing and sometimes ambiguous.

So renamed the attribute to "sockaddr", the function
ic_proxy_extract_addr() is also renamed to ic_proxy_extract_sockaddr().

ProcessCopyOptions checks the option list of COPY command. It's also
called by external table when text/csv format is used. It's better
not to mix external table specific options here and check them
separately.

Checking custom protocol here is not necessary because it's checked
when parsing location urls in GenerateExtTableEntryOptions anyway.

When stash a 'VisimapDelete' to the buffile, we must seek to end of the last
physical file if the buffile contains multiple files. This commit cherry-pick
part of the commit from upstream:

commit 808e13b282efa7e7ac7b78e886aca5684f4bccd3
Author: Amit Kapila <akapila@postgresql.org>
Date:   Wed Aug 26 07:36:43 2020 +0530

    Extend the BufFile interface.

    Allow BufFile to support temporary files that can be used by the single
    backend when the corresponding files need to be survived across the
    transaction and need to be opened and closed multiple times. Such files
    need to be created as a member of a SharedFileSet.

    Additionally, this commit implements the interface for BufFileTruncate to
    allow files to be truncated up to a particular offset and extends the
    BufFileSeek API to support the SEEK_END case. This also adds an option to
    provide a mode while opening the shared BufFiles instead of always opening
    in read-only mode.

    These enhancements in BufFile interface are required for the upcoming
    patch to allow the replication apply worker, to handle streamed
    in-progress transactions.

    Author: Dilip Kumar, Amit Kapila
    Reviewed-by: Amit Kapila
    Tested-by: Neha Sharma
    Discussion: https://postgr.es/m/688b0b7f-2f6c-d827-c27b-216a8e3ea700@2ndquadrant.com

This is a cherry-pick of the change from PR https://github.com/greenplum-db/gporca/pull/607

Avoid costing change for IN predicates on btree indexes

Commit e5f1716 changed the way we handle IN predicates on indexes, it
now uses a more efficient array comparison instead of treating it like
an OR predicate. A side effect is that the cost function,
CCostModelGPDB::CostBitmapTableScan, now goes through a different code
path, using the "small NDV" or "large NDV" costing method. This produces
very high cost estimates when the NDV increases beyond 2, so we
basically never choose an index for these cases, although a btree
index used in a bitmap scan isn't very sensitive to the NDV.

To avoid this, we go back to the old formula we used before commit e5f1716.
The fix is restricted to IN predicates on btree indexes, used in a bitmap
scan.

Add an MDP for a larger IN list, using a btree index on an AO table

Misc. changes to the calibration test program

- Added tests for btree indexes (btree_scan_tests).
- Changed data distribution so that all column values range from 1...n.
- Parameter values for test queries are now proportional to selectivity,
  a parameter value of 0 produces a selectivity of 0%.
- Changed the logic to fake statistics somewhat, hopefully this will
  lead to more precise estimates. Incorporated the changes to the
  data distribution with no more 0 values. Added fake stats for
  unique columns.
- Headers of tests now use semicolons to separate parts, to give
  a nicer output when pasting into Google Docs.
- Some formatting changes.
- Log fallbacks.
- When using existing tables, the program now determines the table
  structure (heap or append-only) and the row count.
- Split off two very slow tests into separate test units. These are
  not included when running "all" tests, they have to be run
  explicitly.
- Add btree join tests, rename "bitmap_join_tests" to "index_join_tests"
  and run both bitmap and btree joins
- Update min and max parameter values to cover a range that includes
  or at least is closer to the cross-over between index and table scan
- Remove the "high NDV" tests, since the ranges in the general test
  now include both low and high NDV cases (<= and > 200)
- Print out selectivity of each query, if available
- Suppress standard deviation output when we execute queries only once
- Set search path when connecting
- Decrease the parameter range when running bitmap scan tests on
  heap tables
- Run btree scan tests only on AO tables, they are not designed
  for testing index scans

Updates to the experimental cost model, new calibration

1. Simplify some of the formulas, the calibration process seemed to justify
   that. We might have to revisit if problems come up. Changes:
   - Rewrite some of the formulas so the costs per row and costs per byte
     are more easy to see
   - Make the cost for the width directly proportional
   - Unify the formula for scans and joins, use the same per-byte costs
     and make NDV-dependent costs proportional to num_rebinds * dNDV,
     except for the logic in item 3.

   That makes the cost for the new experimental cost model a simple linear formula:

   num_rebinds * ( rows * c1 + rows * width * c2 + ndv * c3 + bitmap_union_cost + c4 ) + c5

   We have 5 constants, c1 ... c5:

   c1: cost per row (rows on one segment)
   c2: cost per byte
   c3: cost per distinct value (total NDV on all segments)
   c4: cost per rebind
   c5: initialization cost
   bitmap_union_cost: see item 3 below

2. Recalibrate some of the cost parameters, using the updated calibration
   program src/backend/gporca/scripts/cal_bitmap_test.py

3. Add a cost penalty for bitmap index scans on heap tables. The added
   cost takes the form bitmap_union_cost = <base table rows> * (NDV-1) * c6.

   The reason for this is, as others have pointed out, that heap tables
   lead to much larger bit vectors, since their CTIDs are more spaced out
   than those of AO tables. The main factor seems to be the cost of unioning
   these bit vectors, and that cost is proportional to the number of bitmaps
   minus one and the size of the bitmaps, which is approximated here by the
   number of rows in the table.

   Note that because we use (NDV-1) in the formula, this penalty does not
   apply to usual index joins, which have an NDV of 1 per rebind. This is
   consistent with what we see in measurements and it also seems reasonable,
   since we don't have to union bitmaps in this case.

4. Fix to select CostModelGPDB for the 'experimental' model, as we do in 5X.

5. Calibrate the constants involved (c1 ... c6), using the calibration program
   and running experiments with heap and append-only tables on a laptop and
   also on a Linux cluster with 24 segments. Also run some other workloads
   for validation.

6. Give a small initial advantage to bitmap scans, so they will be chosen over
   table scans for small tables. Otherwise, small queries will
   have more or less random plans, all of which cost around 431, the value
   of the initial cost. Added a 10% advantage of the bitmap scan.

* Port calibration program to Python 3

- Used 2to3 program to do the basics.
- Version parameter in argparse no longer supported
- Needs additional option in connection string to keep the search path
- The dbconn.execSQL call can no longer be used to get a cursor,
  this was probably a non-observable defect in the Python 2 version
- Needed to use // (floor division) in some cases
Co-authored-by: NDavid Kimura <dkimura@vmware.com>

* Improve partition elimination when indexes are present (port from 6X)

* Use original join pred for DPE with index nested loop joins

Dynamic partition selection is based on a join predicate. For index
nested loop joins, however, we push the join predicate to the inner
side and replace the join predicate with "true". This meant that
we couldn't do DPE for nested index loop joins.

This commit remembers the original join predicate in the index nested
loop join, to be used in the generated filter map for DPE. The original
join predicate needs to be passed through multiple layers.

* SPE for index preds

Some of the xforms use method CXformUtils::PexprRedundantSelectForDynamicIndex
to duplicate predicates that could be used both as index predicates and as
partition elimination predicates. The call was missing in some other xforms.
Added it.

* Changes to equivalent distribution specs with redundant predicates

Adding redundant predicates causes some issues with generating
equivalent distribution specs, to be used for the outer table of
a nested index loop join. We want the equivalent spec to be
expressed in terms of outer references, which are the columns of
the outer table.

By passing in the outer refs, we can ensure that we won't replace
an outer ref in a distribution spec with a local variable from
the original distribution spec.

Also removed the asserts in CPhysicalFilter::PdsDerive that ensure the
distribution spec is complete (consisting of only columns from the
outer table) after we see a select node. Even without my changes, the
asserts do not always hold, as this test case shows:

  drop table if exists foo, bar;
  create table foo(a int, b int, c int, d int, e int) distributed by(a,b,c);
  create table bar(a int, b int, c int, d int, e int) distributed by(a,b,c);

  create index bar_ixb on bar(b);

  set optimizer_enable_hashjoin to off;
  set client_min_messages to log;

  -- runs into assert
  explain
  select *
  from foo join bar on foo.a=bar.a and foo.b=bar.b
  where bar.c > 10 and bar.d = 11;

Instead of the asserts, we now use the new method of passing in the
outer refs to ensure that we move towards completion. We also know
now that we can't always achieve a complete distribution spec, even
without redundant predicates.

* MDP changes

Various changes to MDPs:

- New SPE filters used in plan
- New redundant predicates (partitioning or on non-partitioning columns)
- Plan space changes
- Cost changes
- Motion changes
- Regenerated, because plan switched to a hash join, so used a guc
  to force an index plan
- Fixed lookup failures
- Add mdp where we try unsuccessfully to complete a distribution spec

* ICG result changes

- Test used the 'experimental' cost model to force an index scan, but we
  now get the index scan even with the default cost model (plans currently
  fall back).

This is a cherry-pick of commit 4a7a6821 from the 6X_STABLE branch.

They have the same no-op implementation as the overridden base method,
and they aren't called anywhere.

The method called doesn't actually do any printing, and we don't assert
on the output. Removing the call doesn't even change the program output.

While working on extracting a common implementation of DbgPrint() into a
mixin (commit forthcoming), I ran into the curious phenomenon that is
the non-const CMemo::OsPrint. I almost dropped the requirement that
DbgPrint requires "OsPrint() const", before realizing that the root
cause is CSyncList has non-const Next() and friends. And that could be
easily fixed. Make it so.

While we're at it, also fixed a fairly obvious omission in
CMemo::OsPrint where the output stream parameter was unused. We output
to an unrelated "auto" stream instead. This was probably never noticed
because we were relying on the assumption that streams are always
connected to standard output.

These are classes that are only implementing an OsPrint method just so
that they can have a debug printing facility. They are not overriding
anything from a base class, so the "virtual" was just a bad habit.
Remove them.

I looked through the history, this class was dead on arrival and *never*
used. Ironically, we kept adding #include for its header over the years
to places that didn't use the class.

Mortality date, in chronological order:

gpos/memory/ICache.h: Added in 2010, orphaned in 2011 (private commit)
CL 90194

gpopt/utils/COptClient.h and gpopt/utils/COptServer.h: Added in 2012,
orphaned in 2015 (private commit) MPP-25631

gpopt/base/CDrvdPropCtxtScalar.h: Dead on arrival when added in 2013

gpos/error/CAutoLogger.h: Added in 2012, orphaned in 2014 (private
commit) CL 189022

unittest/gpos/task/CWorkerPoolManagerTest.h: Added in 2010, orphaned in
2019 in commit 61c7405a "Remove multi-threading code"
(greenplum-db/gporca#510)

unittest/gpos/task/CAutoTaskProxyTest.h wasn't removed in commit
61c7405a probably because there was an reference in
CWorkerPoolManagerTest.h which is was also left behind (chained
orphaning).

Co-authored-by: NGang Xiong <gangx@vmware.com>

On QD, it tracks whether QE wrote_xlog in the libpq connection.

The logic is, if QE writes xlog, it'll send a libpq msg to QD. But the
msg is sent in ReadyForQuery. So, before QE execute this function, the
QE may already send back results to QD. Then when QD process this
message, it does not read the new wrote_xlog value. This makes the
connection still contains the previous dispatch wrote_xlog value,
which will affect whether choosing one phase commit.

The issue only happens when the QE flush the libpq msg before the
ReadyForQuery function, hard to find a case to cover it.
I found the issue when I playing the code to send some information from
QE to QD. And it breaks the gangsize test which shows the commit info.

If cdbcomponent_getCdbComponents() caught an error threw by
function getCdbComponents, FtsNotifyProber would be called.
But if it happened inside fts process, ftp process would hang.

Skip fts probe for fts process, after that, under the same
situation, fts process would exit and then be restarted by
postmaster.

Collect tuple relead pgstat table info from segments. Then the
auto-analyze could consider partition tables now. Since before, we don't
have accurate pgstat for partition leaf table. This kind of info is counted
through the access method on segments and we used to collect them by the
estate es_processed count on QD. So if insert into the root partition
table, we can not know how many tuples inserted into a leaf, autovacuum
never trigger auto-ANALYZE for leaf table.

The idea is, for writer QE, report current nest level xact tables pgstat
to QD through libpq at the end of a query statement. For a single
statement, it wouldn't operate too many tables, so the effort is really
small.
And on QD, retrieve and combine these tables' stat from the dispatch
result and add to current nest level xact pgstats.
Now we can remove the old pgstat collection code on QD.

The pgstat for a table could be view by query `pg_stat_all_tables_inernal`.
And now, except for the scan related counters, other counters should be accurate.
On master, the table's pgstat of scan related counters are not gathered
from segments yet, this requires extra work. The current implementation
is already enough for supporting auto-ANALYZE on partition table.
Reviewed-by: NHubert Zhang <hzhang@pivotal.io>

In some cases, some signals (like SIGQUIT) that should only be
processed by the main thread of the postmaster may be dispatched to rxThread.
So we should and it is safe to block all signals in the udp pthreads.

Fix #11006

Previously, GPDB did not support the SQL "EXCLUDE [CURRENT ROW | GROUP |
TIES]" syntax in window functions. We got support for that from upstream
with the PostgreSQL v12 merge. That left the GUC obsolete and unused.

Update the 'olap_window' test accordingly. NOTE: 'olap_window' test isn't
currently run as part of the regression suite! I don't know why it's been
neglected like that, but that's not this patch's fault. The upstream
'window' test has queries with the EXCLUDE clause, so it's covered.

Reviewed-by: Jimmy Yih

GPCC want to hook query like
- create table ... as select ...
- create materialized view ... as select ...

These assertions started getting tripped in the previous commit when
adding tests, but aren't related to the Epsilon change. Rather, we're
calculating the frequency of a singleton bucket using two different
methods which causes this assertion to break down. The first method
(calculating the upper_third) assumes the singleton has 1 NDV and that there is an even distribution
across the NDVs. The second (in GetOverlapPercentage) calculates a
"resolution" that is based on Epsilon and assumes the bucket contains
some small Epsilon frequency. It results in the overlap percentage being
too high, instead it too should likely be based on the NDV.

In practice, this won't have much impact unless the NDV is very small.
Additionally, the conditional logic is based on the bounds, not
frequency. However, it would be good to align in the future so our
statistics calculations are simpler to understand and predictable.

For now, we'll remove the assertions and add a TODO. Once we align the
methods, we should add these assertions back.

When merging statistics buckets for UNION and UNION ALL queries
involving a column that maps to Double (eg: floats, numeric, time
related types), we could end up in an infinite loop. This occurred if
the bucket boundaries that we compared were within a very small value,
defined in Orca as Epsilon. While we considered that two values were
equal if they were within Epsilon, we didn't when computing whether
datum1 < datum2. Therefore we'd get into a situation where a datum
could be both equal to and less than another datum, which the logic
wasn't able to handle.

The fix is to make sure we have a hard boundary of when we consider a
datum less than another datum by including the epsilon logic in all
datum comparisons. Now, 2 datums are equal if they are within epsilon,
but datum1 is less than datum 2 only if datum1 < datum2 - epsilon.

Also add some tests since we didn't have any tests for types that mapped
to Double.

In commit c5f6dbbe, we changed the row and cost estimates on plan nodes
to represent per-segment costs. That made some estimates worse, because
the effects of the estimate "clamping" compounds. Per my comment on the
PR back then:

> One interesting effect of this change, that explains many of the
> plan changes: If you have a table with very few rows, or e.g. a qual
> like id = 123 that matches exactly one row, the Seq/Index Scan on it
> will be marked with rows=1. It now means that we estimate that every
> segment returns one row, although in reality, only one of them will
> return a row, and the rest will return nothing. That's because the
> row count estimates are "clamped" in the planner to at least
> 1. That's not a big deal on its own, but if you then have e.g. a
> Gather Motion on top of the Scan, the planner will estimate that the
> Gather Motion returns as many rows as there are segments. If you
> have e.g. 100 segments, that's relatively a big discrepancy, with
> 100 rows vs 1. I don't think that's a big problem in practice, I
> don't think most plans are very sensitive to that kind of a
> misestimate. What do you think?
>
> If we wanted to fix that, perhaps we should stop "clamping" the
> estimates to 1. I don't think there's any fundamental reason we need
> to do it. Perhaps clamp down to 1 / numsegments instead.

But I came up with a less intrusive idea, implemented in this commit:
Most Motion nodes have a "parent" RelOptInfo, and the RelOptInfo
contains an estimate of the total number of rows, before dividing it
with the number of segments or clamping. So if the row estimate we get
from the subpath seems clamped to 1.0, we look at the row estimate on
the underlying RelOptInfo instead, and use that if it's smaller. That
makes the row count estimates better for plans that fetch a single row
or a few rows, same as they were before commit c5f6dbbe. Not all
RelOptInfos have a row count estimate, and the subpaths estimate is
more accurate if the number of rows produced by the path differs from
the number of rows in the underlying relation, e.g.  because of a
ProjectSet node, so we still prefer the subpath's estimate if it
doesn't seem clamped.
Reviewed-by: NZhenghua Lyu <zlv@pivotal.io>

It was handled in expression_tree_mutator(), which is why everything
worked, but that's not the right place. expression_tree_mutator() is
supposed to handle nodes that can appear in expressions, and
plan_tree_mutator() is supposed to handle Plan nodes.
Reviewed-by: NZhenghua Lyu <zlv@pivotal.io>

In buildGangDefinition, newGangDefinition->db_descriptors are
initialized one by one, but newGangDefinition->size was already
set to its final value. If an error was caught, its size should
be reset to the right number.

Append-optimized tables do not contain transaction information in
their tuples.  Therefore, pg_class.relfrozenxid must remain invalid.
This is being done correctly during table creation, however, when the
table was rewritten, the relfrozenxid was accidentally set.  Fix it
such that diff with upstream is minimised.  In particular, the function
"should_have_valid_relfozenxid" is removed.

The fixme comments that led me to this bug are also removed.

Reviewed by: Ashwin Agrawal

Postgresql libpq document:

> Note that when PQconnectStart or PQconnectStartParams returns a
> non-null pointer, you must call PQfinish when you are finished
> with it, in order to dispose of the structure and any associated
> memory blocks. **This must be done even if the connection attempt
> fails or is abandoned**.

However, cdbconn_disconnect() function did not call PQfinish when
CONNECTION_BAD, it can cause socket leaks (CLOSE_WAIT state).

This conforms our code to the best practice that each polymorphic
function should have exactly one of "virtual", "override", and "final"
specifier. I made this change using the following invocation:

clang-tidy -checks '-*,modernize-use-override'

Once we've made this change, ideally this practice can be enforced in
CI. We can just run clang-tidy with a single "modernize-use-override"
check to start with. Or we can see if our compilers are helpful enough.
Fortunately Clang already issues warnings (turned into errors by
-Werror) when we have inconsistent use of "override", and GCC appears to
have something similar (-Wsuggest-override) in versions 9.2 and later.

Now that we are explicitly declaring copy-assignment operators and copy
constructors as deleted, we should also make them public -- private and
=delete don't make much sense in combination, and this results in the
best diagnostics in practice [1].

In the previous commit where private unimplemented special member
functions are changed to be declared as deleted, we left the new
declarations private. This follows up by moving those deleted functions
to the public section of their classes.

I made this change guided by tooling: even though it doesn't offer a
fix, clang-tidy is useful enough to emit diagnostics that look like the
following:

/home/pivotal/workspace/gpdb/src/backend/gporca/libgpopt/include/gpopt/base/CColRef.h:76:2: warning: deleted member function should be public [modernize-use-equals-delete]
        CColRef(const CColRef &) = delete;
        ^

The process involved of making this change is a tale of much sorrow,
blood and tears. Suffice it to say 20 different regular expressions were
involved, and I'm edging closer to a PTSD when looking at backslashes.

References:
[1] https://abseil.io/tips/143#summary

This commit replaces two pre-C++ 11 practices with their modern, more
intent-expressive equivalents: "disallowed" copy and assignments, and
pairs of empty braces for special member function (destructors, default
constructors, and etc) bodies.

"Disallowed" copy constructors / assignment
-------------------------------------------
Old: private, unimplemented copy constructors and copy-assignment
operators in classes. These are usually paired with a semi-descriptive
comment.

New: publicly declare them as "= delete".

Fun fact: we had 13 spellings in comments on disallowed copy
constructors:

01. disable copy ctor
02. hidden copy ctor
03. inaccessible copy ctor
04. no copy ctor
05. no default copy ctor
06. private copy ctor
07. private no copy ctor
08. disabled copy constructor
09. no copy constructor
10. private copy constructor
11. copy c'tor - not defined
12. no copy c'tor
13. private copy c'tor

This commit removes all of them, because the new code ("~T() = delete")
already clearly expresses the intent of disallowing copy and assignment.

To keep the history clear, this commit leaves the declaration of
"prohibited" functions private. A forthcoming commit will wholesale
change them to public.

Defaulted special member functions
----------------------------------
Old:
struct A {
  A() {}
  ~A();
};
A::~A() {}

New:
struct A {
  A() = default;
  ~A();
};
A::~A() = default;

Replacing empty braces with defaulting not only makes them more clear,
they also enable more opportunities in compiler optimizations, as e.g.
some defaulted functions might be recognized as trivial.

Most of this commit is produced by running clang-tidy with an invocation
like the following (plus some CMake and shell tricks):

clang-tidy-12 -header-filter 'gpdbcost|gpopt|gpos|naucrates' -checks '-*,modernize-use-equals-delete,modernize-use-equals-default'

The tool uses a slightly conservative heuristic to detect a large
portion of the two outdated patterns above and rewrite them into using
"= delete" and "= default". Making the "= delete" functions public, is
sadly a FIXME item, so we'll have to do it by hand (in a forthcoming
commit).

The current setup in CMake (and Makefile's too, but that's an even
harder problem) leads to equivalent-but-not-identical header include
paths (-I) for the same directory, e.g. -Ilibgpopt/include vs
-Ilibgpdbcost/../libgpopt/include .

This confuses Clang-based tooling into identifying multiple paths for
the same header -- the difference being the extra sibling directory
followed by dot-dot, or "niece" directory followed by two levels of
dot-dot, and so forth -- as different headers. That, in turn, undermines
the conflict resolution and edit deduplication features in Clang's
refactoring engine, leading to duplicate edits when applying FixIt's.

This commit applies some fairly simple fixes to spell the sibling
directories in a way that generates consistent include paths, so that
Clang tooling are more functional. The Makefile's are left unchanged as
that is a lot more difficult to make "right". One can argue that we
_might_ want to instead transform the intermediate representation of
Clang's "replacement" YAML files, but that's left for another day.

During the development of a forthcoming commit that replaces private
unimplemented special member functions with explicitly deleted ones, we
got a surprising improvement of compiler diagnostics: Clang started to
see a lot of unused private fields that are masked by the fact that
there were unimplemented functions in the class. This makes sense
because the ostensibly unused field _could be_ used by a method whose
definition compiler hasn't seen in the current translation unit -- it
also suggests that the compiler would be better equipped at detecting
this if we had used whole-program analysis.

A sample of the errors looks like the following:

In file included from CMiniDumper.cpp:14:
In file included from ../../../../../../src/backend/gporca/libgpos/include/gpos/error/CErrorContext.h:17:
../../../../../../src/backend/gporca/libgpos/include/gpos/error/CMiniDumper.h:32:15: error: private field 'm_mp' is not used [-Werror,-Wunused-private-field]
        CMemoryPool *m_mp;
                     ^
1 error generated.

There are 12 such warnings, and this commit fixes them all. Note that
code mortality is a chain reaction: oftentimes, a variable (including
parameter) is only live because it's passed to another variable. While I
was at it, I also performed chained removal of variables and parameters
that became dead after removing the dead fields.

We have a bunch of classes with private fields that are used only in
debug builds, some of them are probably opportunities for complete
removal. This is exposed by an upcoming commit that enforces the use of
"=delete" and "=default" throughout the codebase.

I've attempted to solve this by adding the GPOS_ASSERTS_ONLY attribute,
but GCC doesn't like that, throwing errors like the following:

In file included from ../src/backend/gporca/libgpos/include/gpos/common/clibwrapper.h:22,
                 from ../src/backend/gporca/libgpos/include/gpos/error/CMessage.h:21,
                 from ../src/backend/gporca/libgpos/include/gpos/error/CMessageTable.h:14,
                 from ../src/backend/gporca/libgpos/include/gpos/error/CMessageRepository.h:14,
                 from ../src/backend/gporca/libgpos/src/_api.cpp:15:
../src/backend/gporca/libgpos/include/gpos/attributes.h:15:43: error: ‘unused’ attribute ignored [-Werror=attributes]
   15 | #define GPOS_UNUSED __attribute__((unused))
      |                                           ^
../src/backend/gporca/libgpos/include/gpos/attributes.h:21:27: note: in expansion of macro ‘GPOS_UNUSED’
   21 | #define GPOS_ASSERTS_ONLY GPOS_UNUSED
      |                           ^~~~~~~~~~~
../src/backend/gporca/libgpos/include/gpos/memory/CAutoMemoryPool.h:56:31: note: in expansion of macro ‘GPOS_ASSERTS_ONLY’
   56 |  ELeakCheck m_leak_check_type GPOS_ASSERTS_ONLY;
      |                               ^~~~~~~~~~~~~~~~~
cc1plus: all warnings being treated as errors

So we're back to the good ol' #ifdef GPOS_DEBUG.

This is the first of a pair of manual changes. In the immediately
following commit I'll remove the remaining (unconditionally) unused
private fields.

Reviewed-by: NPaul Guo <guopa@vmware.com>

Postgres 991f3e5a introduce new error
message fields, but cdbdisp_get_PQerror() did not extract these newly
added message field. These fields client cannot see from libpq.

This fixes https://github.com/greenplum-db/gpdb/issues/7934.
Co-authored-by: NAshwin Agrawal <aashwin@vmware.com>
Reviewed-by: NHeikki Linnakangas <hlinnaka@iki.fi>