As we merge with upstream and by that keep refining the Postgres
planner, legacy planner is no longer a suitable name. This changes
all variations of the spelling (legacy planner, legacy optimizer,
legacy query optimizer etc) to say "Postgres" rather than "legacy".
Reviewed-by: NVenkatesh Raghavan <vraghavan@pivotal.io>
Reviewed-by: NDavid Yozie <dyozie@pivotal.io>
Reviewed-by: NGeorgios Kokolatos <gkokolatos@pivotal.io>

explain_format tests validate for memory related information. But the
printing for that information is not stable and varies based on orca vs
planner, assert enabled vs disabled, query reusing the slice vs run on
fresh session. Plus, future modifications not related to explain
formatting can cause this test to fail. Hence, only minimal explain
format validation which is found to be stable currently is being
retained for this test.

Better alternative needs to be found to perform for full validation for
explain formatting, seems sql way is too fragile for it.
Co-authored-by: NAshwin Agrawal <aagrawal@pivotal.io>

The Greenplum specific error handling via ereport()/elog() calls was
in need of a unification effort as some parts of the code was using a
different messaging style to others (and to upstream). This aims at
bringing many of the GPDB error calls in line with the upstream error
message writing guidelines and thus make the user experience of
Greenplum more consistent.

The main contributions of this patch are:

* errmsg() messages shall start with a lowercase letter, and not end
  with a period. errhint() and errdetail() shall be complete sentences
  starting with capital letter and ending with a period. This attempts
  to fix this on as many ereport() calls as possible, with too detailed
  errmsg() content broken up into details and hints where possible.

* Reindent ereport() calls to be more consistent with the common style
  used in upstream and most parts of Greenplum:

	ereport(ERROR,
			(errcode(<CODE>),
			 errmsg("short message describing error"),
			 errhint("Longer message as a complete sentence.")));

* Avoid breaking messages due to long lines since it makes grepping
  for error messages harder when debugging. This is also the de facto
  standard in upstream code.

* Convert a few internal error ereport() calls to elog(). There are
  no doubt more that can be converted, but the low hanging fruit has
  been dealt with. Also convert a few elog() calls which are user
  facing to ereport().

* Update the testfiles to match the new messages.

Spelling and wording is mostly left for a follow-up commit, as this was
getting big enough as it was. The most obvious cases have been handled
but there is work left to be done here.

Discussion: https://github.com/greenplum-db/gpdb/pull/6378Reviewed-by: NAshwin Agrawal <aagrawal@pivotal.io>
Reviewed-by: NHeikki Linnakangas <hlinnakangas@pivotal.io>

We had changed this in GPDB, to print less parens. That's fine and dandy,
but it hardly seems worth it to carry a diff vs upstream for this. Which
format is better, is a matter of taste. The extra parens make some
expressions more clear, but OTOH, it's unnecessarily verbose for simple
expressions. Let's follow the upstream on this.

These changes were made to GPDB back in 2006, as part of backporting
to EXPLAIN-related patches from PostgreSQL 8.2. But I didn't see any
explanation for this particular change in output in that commit message.

It's nice to match upstream, to make merging easier. However, this won't
make much difference to that: almost all EXPLAIN plans in regression
tests are different from upstream anyway, because GPDB needs Motion nodes
for most queries. But every little helps.

In aligned format, there is an end-of-line marker at the end of each line,
and its position depends on the longest line. If the width changes, all
lines need to be adjusted for the moved end-of-line-marker.

While testing this, we found out that 'atmsort' had been doing bad things
to the YAML output before:

    -- Check Explain YAML output
    EXPLAIN (FORMAT YAML) SELECT * from boxes LEFT JOIN apples ON apples.id = boxes.apple_id LEFT JOIN box_locations ON box_locations.id = boxes.location_id;
    QUERY PLAN
    ___________
    {
      'id' => 1,
      'short' => '- Plan:                                                  +'
    }
    GP_IGNORE:(1 row)

In other worse, we were not comparing the output at all, except for that one
line that says "Plan:". The access plan for one of the queries had changed,
from a Left Join to a Right Join, and we still had the old plan memorized
in expected output, but the test was passing because atmsort hid the issue.
This commit fixes the expected output for the new plan.

 - Display Worker information when Gang is active
 - On Explain Analyze, when there are multiple Gang Members active the
information about the workers (errors, canceled, not dispatched, aborted
and ok) is displayed for the YAML, JSON and XML format
 - Correct explain_format without optimizer
 - Correct orca enabled test
 - Correct fixme related to the display of extra text
 - Memory used is variable
The tests were failing because "Memory used" in YML is variable and
the tests was not ready for it
 - Ensure that the tests do not fail due to white spaces
Tests were failing due to whitespaces after the replacement on
"Total memory used across slices"
 - Extra information was creating the multiple groups

Display the amount of memory used by ORCA when doing and explain analyze
with the GUT `explain_memory_verbosity` set to `summary`

Add YAML, JSON and XML representation for simple statistics on the
slices

Add other variables fields
Add explain test to the parallel group for GreenPlum
Add optimizer tests

This property should be used on the sql regression tests and will
activate or deactivate the usage of the explain parser.
Added basic format test to explain parsing