gp_resource_manager is reserved for later use to switch resource control stratagy from resource queue to an under-developing resource statagy named resource group. Eg:

gpconfig -c gp_resource_manager -v 'group'
gpconfig -c  gp_resource_manager -v 'queue'

To make it work, a restart of cluster is needed.

The gp_enable_alter_table_inherit_cols GUC was used to allow a list
of columns to override the attribute discovery for inheritance in
ALTER TABLE INHERIT. According to code comments the only consumer
of this was gpmigrator, but no callsite remains and no support in
pg_dumpall remains either. Remove the leftovers of this to avoid a
potential footgun and get us closer to upstream code.

The gp_external_grant_privileges GUC was needed before 4.0 to let
non superusers create external tables for gphdfs and http protocols.
This GUC was however deprecated during the 4.3 cycle so remove all
traces of it. The utility of the GUC was replaced in 4.0 when rights
management for external tables was implemented with the normal GRANT
REVOKE framework so this has been dead code for quite some time.

Remove GUC, code which handles it, all references to it from the
documentation and a release notes entry.

The gp_eager_hashtable_release GUC was deprecated in version 4.2
in 2011 when the generic eager free framework was implemented. The
leftover gp_eager_hashtable_release was asserted to be true and
never intended to be turned off. The same body of work deprecated
the max_work_mem setting which was bounding the work_mem setting.
While not technically tied to eager hashtable release, remove as
well since it's deprecated, undocumented and not terribly useful.

Relevant commit in closed source repo is 88986b7d

The gp_hashagg_compress_spill_files GUC was deprecated in 2010 when
it was replaced by gp_workfile_compress_algorithm. The leftovers
haven't done anything for quite some time so remove GUC.

Relevant commit in closed source repo is c1ce9f03

Signed-off-by Gang Xiong <gxiong@pivotal.io>

It hasn't done anything since 2010. If I'm reading the commit log
correctly, it was added and deprecated only a few months apart, and
probably hasn't done anything in any released version.

And other misc cleeanup.

Reset mppIsWriter field of PGPROC to false in hook function of GUC gp_session_role if the new value is GP_ROLE_UTILITY(#1421)

When someone is connecting to a segment in utility mode, and there exists a connection
from QD to this segment having a same session id coincidently, reader QE on this
segment may possibly treat the utility backend as its corresponding writer QE, this may lead
to confusion on shared snapshot, and reader QE of extended query may report error saying it
cannot find snapshot temp file.

We avoid this by excluding utility backend from writer list.

Signed-off-by Pengzhou Tang <ptang@pivotal.io>

In many places where we had used a mixture of spaces and tabs for
indentation, new versions of gcc complained about misleading indentation,
because gcc doesn't know we're using tab width of 4. To fix, make the
indentation consistent in all the places where gcc gave a warning. Would
be nice to fix it all around, but that's a lot of work, so let's do it
in a piecemeal fashion whenever we run into issues or need to modify a
piece of code anyway.

For some files, especially the GPDB-specific ones, I ran pgindent over
the whole file. I used the pgindent from PostgreSQL master, which is
slightly different from what was used back 8.3 days, but that's what I had
easily available, and that's what we're heading to in the future anyway.
In some cases, I didn't commit the pgindented result if there were
funnily formatted code or comments that would need special treatment.

For other places, I fixed the indentation locally, just enough to make the
warnings go away.

I also did a tiny bit of other trivial cleanup, that I happened to spot
while working on this, although I tried to refrain from anything more
extensive.

The previous commits have removed all usage of CaQL. It's no longer
needed.

The feature was disabled, by removing it from guc.c, only months after
it was introduced, back in 2009. I'm not sure if it ever made it into a
public release. We have no plans to resurrect it, and it has surely
bitrotted so badly that even if we did, it would be better to start from
scratch.

Currently gp_connections_per_thread=0 means using main thread to
do dispatch instead of creating new threads. It's not working if
segments report error before sending back any data.
For example:
create table foo(id int);
insert into foo values(0);
set gp_connections_per_thread=0;
select 100/id from foo;

We disable it for now and will reenable it when we have the new
implementation of non-threaded dispatcher.

1) add one new type of gang: singleton reader gang.
2) change interface of allocateGang.
3) handling exceptions during gang creation: segment down and segment reset.
4) cleanup some dead code.

Codes of ic_tcp and ic_udp are not maintained any more, ic_udpifc is
the only interconnect type for now. We keep the gp_interconnect_type
guc for backward compatibility.

It was just syntax and catalogs, you couldn't actually do anything useful
with it. Remove it, so that we have less code to maintain, until it's time
to merge this stuff from upstream again when we merge with PostgreSQL 8.4.
It's probably easier to merge this back at that point than maintain this
backported version in the meanwhile. Less effort now, until we reach that
point, and once we get to the point in 8.4 that we merge this in, we'll
have all the preceding patches applied already, so it should merge quite
smoothly.