Currently upstream supports two options: seq_page_cost and random_page_cost. In theory we possibly do not need to mpp-ify this utility stmt, but it is better to do that in case upstream or greenplum add some other option that affects QE.

PG9.4 starts to allow the WITH syntax to support options
in create tablespace. Greenplum previously used the OPTIONS
syntax to support per segment location. Let's union them all to
use the WITH syntax only, following upstream.

Note the greenplum specific OPTIONS exists in gpdb master only.

Alter tablespace needs to copy all underlying files of table from one tablespace
to other. For AO/CO tables this was implemented using full directory scan to
find files and copy when persistent tables were removed. This gets very
inefficient and varies in performance based on number of files present in the
directory. Instead use the same optimization logic used for `mdunlink_ao()`
leveraging known file layout for AO/CO tables.

Also, old logic had couple of bugs:
- missed coping the base or .0 file. Which means data loss if table was altered in past.
- xlogging even for temp tables

These are fixed as well with this patch. Additional tests added to cover for
those missing scenaiors. Also, moved the AO specific code to aomd.c, out of
tablecmds.c file to reduce conflicts to upstream.

The pg_tablespace_location function only returns the tablespace
location of the connected segment. For Greenplum, we need to be able
to easily see the tablespace locations for all segments. This is
especially needed because we support defining tablespace locations
per-segment.

The old filespace concept allowed for different physical location per
segment/mirror, whereas the tablespace definition only support a
single location.  Tablespaces are backed by a symlink which can be
changed without any changes required on the database level, as long as
the system is turned off at the time. To recreate the filespace
functionality, a process like this would be required:

  1. CREATE TABLESPACE foo LOCATION '/foo/bar';
  2. Shut down the cluster
  3. Move the symlinks to preferred location on each segment
  4. Start cluster back up

Since step 3 require accessing each segment in the cluster, it is
preferable to allow syntax do to this automatically. This commit adds
support for specifying per segment overrides from the default LOCATION
by using an optional OPTIONS clause to specify the segment's content
ID and desired non-default location:

  CREATE TABLESPACE foo LOCATION '/foo/bar'
    OPTIONS (content1 '/content1/bar', content2 '/content2/bar');

Any segment content ID not listed in the OPTIONS clause will get the
LOCATION as its tablespace symlink. The spclocation will be set to
LOCATION, but that column will shortly go away as it's no longer used.

Greenplum Developers mailing thread:
https://groups.google.com/a/greenplum.org/forum/#!msg/gpdb-dev/vmdRjm54on8/nj2SSns0AwAJCo-authored-by: NJimmy Yih <jyih@pivotal.io>