This removes a whole set of GUCs which are no longer used in the
codebase. Also remove relevant documentation.
Reviewed-by: NAshwin Agrawal <aagrawal@pivotal.io>
Reviewed-by: NHeikki Linnakangas <hlinnakangas@pivotal.io>
Reviewed-by: NGeorgios Kokolatos <gkokolatos@pivotal.io>

The GUC which enables recursive CTEs is in the currently released
version called gp_recursive_cte_prototype, but in order to reflect
the current state of the code it's now renamed to gp_recursive_cte.
By default the GUC is still off, but that might change before we
ship the next release.

The previous GUC name is still supported, but marked as deprecated,
in order to make upgrades easier.
Reviewed-by: NIvan Novick <inovick@pivotal.io>
Reviewed-by: NGeorgios Kokolatos <gkokolatos@pivotal.io>

This method was introduced to improve the data redistribution
performance during gpexpand phase2, however per benchmark results the
effect does not reach our expectation.  For example when expanding a
table from 7 segments to 8 segments the reshuffle method is only 30%
faster than the traditional CTAS method, when expanding from 4 to 8
segments reshuffle is even 10% slower than CTAS.  When there are indexes
on the table the reshuffle performance can be worse, and extra VACUUM is
needed to actually free the disk space.  According to our experiments
the bottleneck of reshuffle method is on the tuple deletion operation,
it is much slower than the insertion operation used by CTAS.

The reshuffle method does have some benefits, it requires less extra
disk space, it also requires less network bandwidth (similar to CTAS
method with the new JCH reduce method, but less than CTAS + MOD).  And
it can be faster in some cases, however as we can not automatically
determine when it is faster it is not easy to get benefit from it in
practice.

On the other side the reshuffle method is less tested, it is possible to
have bugs in corner cases, so it is not production ready yet.

In such a case we decided to retire it entirely for now, we might add it
back in the future if we can get rid of the slow deletion or find out
reliable ways to automatically choose between reshuffle and ctas
methods.

Discussion: https://groups.google.com/a/greenplum.org/d/msg/gpdb-dev/8xknWag-SkI/5OsIhZWdDgAJReviewed-by: NHeikki Linnakangas <hlinnakangas@pivotal.io>
Reviewed-by: NAshwin Agrawal <aagrawal@pivotal.io>

* vacuumdb - add missing equal signs =

* CREATE/ALTER/DROP COLLATION. Adds new references for these commands.

* ALTER CONVERSION. Add SET SCHEMA variant.

* ALTER OPERATOR. add SET SCHEMA.

* ALTER OPERATOR CLASS. add SET SCHEMA

* ALTER OPERATOR FAMILY. add SET SCHEMA, FOR SEARCH/FOR ORDER BY

* ALTER ROLE. add REPLICATION/NOREPLICATION options

* ALTER TABLE. Adds collation order, table constraints, many edits.

* reindexdb - add equal signs =

* pg_restore - misc edits, reorg and add some new options

* pg_dumpall - misc edits, new/rearrange options

* pg_dump - misc edits, new/rearrange options, new example

* dropuser - add equal signs =

* droplang - misc edits, add equal signs

* dropdb - add equal signs

* createuser - misc edits, add equal signs

* ALTER TYPE. reorganize synopsis. edits.

* ALTER USER. Add replication/noreplication

* BEGIN. Add DEFERRABLE options

* CLUSTER. Edits to usage notes

* COMMENT. Add new object types, examples

* createlang - misc edits, note, add equal signs

* createdb - misc edits, rearrange options, add equal signs

* clusterdb - add equal signs

* remove space

* note should be info, not warning

* COPY. Add encoding option.

* CREATE DOMAIN. Add collation option.

* CREATE INDEX. A collation.

* CREATE ROLE. Add replication/no replication

* CREATE OPERATOR CLASS. Add FOR SEARCH/ORDER BY.

* CREATE TYPE. Add collatable. Update Compatibility.

* CREATE USER. Add REPLICATION/NOREPLICATION. Make consistent with create role.

* CREATE VIEW. Edits to usage

* CREATE TABLE. Add UNLOGGED table type and COLLATE for table column.
updated - UNLOGGED warnings are per segment.

* CREATE TABLE. Add UNLOGGED table type. UNLOGGED information/warnings are per segment.

* GRANT. minor edits.

* psql - add equal signs, many additions, regorgs, and edits

* COPY - change literal to codeph

* DELETE. Add WITH query clause

* LOCK. SERIALIZABLE xact locking clarifications.

* SET TRANSACTION. Adds deferrable mode.

* DROP COLLATION. Remove redundant privileges statement.

* DROP TYPE. Qualify/hedge type extension compatibility

* EXPLAIN. Add JSON and YAML format examples.

* SET TRANSACTION. Add DEFERRED syntax and note that it is inoperative in gpdb

* REVOKE. add missing spaces in syntax.

* SELECT. Add DISTINCT to several clauses, and may edits.

* TRUNCATE. edits about RESTART and triggers

* VACUUM. deprecate notice for unparenthized syntax.

* SELECT INTO. Add DISTINCT keyword (syntax only), UNLOGGED table keyword and definition.

* INSERT. add WITH [RECURSIVE] clause

* UPDATE. Add WITH [RECURSIVE] clause

* createlang/droplang - remove deprecation note

* CREATE LANGUAGE. Use create extension instead for languages repackaged as extensions.

* pg_dump - --serializable-deferrable is a no-op

* SET TRANSACTION. Add transaction_default_deferred GUC and another unsupported notice

* BEGIN. Note DEFERRABLE has no effect in Greenplum Database

* EXPLAIN. Add missing query from example

* Address review comments.

* edits from Chuck

This re-implements compression that was lost in the WorkFile/BufFile
refactoring. This new implementation uses Zstandard rather than zlib.

Compression can be enabled with "gp_workfile_compression=on". It is
disabled by default.
Reviewed-by: NMel Kiyama <mkiyama@pivotal.io>
Reviewed-by: NYandong Yao <yyao@pivotal.io>

Temporary files have been somewhat inconsistent across different
operations. Some operations used the Greenplum-specific "workfile" API,
while others used the upstream BufFile API directly.

The workfile API provides some extra features: workfiles are visible in
the gp_toolkit views, and you can limit their size with the
gp_workfile_limit_* GUCs. The temporary files that didn't go through the
workfile API were exempt, which is not cool.

To make things consistent, remove the workfile APIs. Use BufFiles
directly everywhere. Re-implement the user-facing view and tracking the
limits, on top of the BufFile API, so that those features are not lost.

The workfile API also supported compressing the temporary files using
zlib. That feature is lost with this commit, but will be re-introduced by
the next commit.

Another feature that this removes, is checksumming temporary files.
That doesn't seem very useful, so we can probably live without it. But
if it's still needed, then that should also be re-implemented on top
of the BufFile API later.

Discussion: https://groups.google.com/a/greenplum.org/d/msg/gpdb-dev/8Xe9MGor0pM/SjqiOo83BAAJReviewed-by: NMel Kiyama <mkiyama@pivotal.io>
Reviewed-by: NYandong Yao <yyao@pivotal.io>

* docs - remove/replace references to gphdfs

* misc edits

* stronger statement (note) about pxf replacing gphdfs

* stronger statement

* edit to note requested by david

* haved -> have... doh

* docs - updates for online expand

* docs - online expand - edits based on review comments.
updated catalog table information.
removed draft comments.

* docs - new GUC optimizer_enable_agg_skew_avoidance

* docs - edits for GUC optimizer_enable_agg_skew_avoidance

* docs - change GUC name to optimizer_force_agg_skew_avoidance

* docs - discuss the global deadlock detector

* some of the edits requested by david

* move opening paragraph to release note

* reorg content, add a bit about local deadlock

* guc can be reloaded

* concurrent update AND DELETE

The support for sending alerts via Email or SNMP was quite a kludge,
and there are much better external tools for managing alerts than
what we can supply in core anyways so this retires the capability.

All references to alert sending in the docs are removed, but there
needs to be section written about how to migrate off this feature
in the release notes or a similar location.

Discussion: https://github.com/greenplum-db/gpdb/pull/6384

Given the online gpexpand work, the gp_num_contents_in_cluster GUC is
unused. So, delete the same from code to avoid confusions and eliminate this
long argument required to start a postgres instance in gpdb.

* Adds PostgreSQL full text search docs to GPDB docs

* Add link to new text search section to internal toc

* Restore unintentional delete

* Fix cross-refs and uppercase GIN

* Small edits and changes from review

* Addresses review comments

- Move text search to Query section of admin guide
- Add chapter tocs
- Add GPText comparison to About Full Text Search topic
- Link fix

Now there is only the async dispatcher.  The dispatcher API interface is
kept so we might add new backend in the future.

The GUC gp_connections_per_thread is also retired which was used to
switch between the async and threaded backends.

This GUC is now unused after the major COPY refactor.
Co-authored-by: NChris Hajas <chajas@pivotal.io>
Co-authored-by: NKevin Yeap <kyeap@pivotal.io>

The GUCs controlling filerep were removed when filerep was replaced
by walrep, but the documentation hasn't caught up.  Remove mentions
of filerep GUCs as they no longer exist.
Reviewed-by: NAsim R P <apraveen@pivotal.io>
Reviewed-by: NMel Kiyama <mkiyama@pivotal.io>

* docs - add GUC gp_resource_group_bypass

Link to HTML on GPDB review doc site.
http://docs-gpdb-review-staging.cfapps.io/review/ref_guide/config_params/guc-list.html#gp_resource_group_bypass

GUC list by category
http://docs-gpdb-review-staging.cfapps.io/review/ref_guide/config_params/guc_category-list.html#topic444

* docs - new GUC gp_resource_group_bypass

--Edits based on review comments.
--Add link to GUC from Admin Guide.
--Update TOC for this guc and other gucs not in TOC.

* docs - review updates for GUC gp_resource_group_bypass

* docs - fix typos in definition of GUC gp_resource_group_bypass

* docs - update to GUC gp_resource_group_bypass based on dev changes.

Instead of completely disabling the generation of Paths with disabled
plan types, add a high penalty to their cost estimates, like in the
upstream. This reduces our diff vs. upstream, making future merges more
straightforward.

Discussion: https://groups.google.com/a/greenplum.org/d/msg/gpdb-dev/Az2cDcqf73g/_tY6Yv1kBgAJCo-authored-by: NDaniel Gustafsson <dgustafsson@pivotal.io>
Reviewed-by: NVenkatesh Raghavan <vraghavan@pivotal.io>
Reviewed-by: NRichard Guo <riguo@pivotal.io>

* Change src/backend/access/external functions to extract and pass query constraints;
* Add a field with constraints to 'ExtProtocolData';
* Add 'pxffilters' to gpAux/extensions/pxf and modify the extension to use pushdown.

* Remove duplicate '=' check in PXF

Remove check for duplicate '=' for the parameters of external table. Some databases (MS SQL, for example) may use '=' for database name or other parameters. Now PXF extension finds the first '=' in a parameter and treats the whole remaining string as a parameter value.

* disable pushdown by default
* Disallow passing of constraints of type boolean (the decoding fails on PXF side);

* Fix implicit AND expressions addition

Fix implicit addition of extra 'BoolExpr' to a list of expression items. Before, there was a check that the expression items list did not contain logical operators (and if it did, no extra implicit AND operators were added). This behaviour is incorrect. Consider the following query:

SELECT * FROM table_ex WHERE bool1=false AND id1=60003;

Such query will be translated as a list of three items: 'BoolExpr', 'Var' and 'OpExpr'.
Due to the presence of a 'BoolExpr', extra implicit 'BoolExpr' will not be added, and
we get an error "stack is not empty ...".

This commit changes the signatures of some internal pxffilters functions to fix this error.
We pass a number of required extra 'BoolExpr's to 'add_extra_and_expression_items'.

As 'BoolExpr's of different origin may be present in the list of expression items,
the mechanism of freeing the BoolExpr node changes.

The current mechanism of implicit AND expressions addition is suitable only before
OR operators are introduced (we will have to add those expressions to different parts
of a list, not just the end, as done now).

adding reference topic for maintenance_work_mem, which is mentioned elsewhere in the docs and in recent postgresql 8.4 merges (#4422)

* docs: Add guc verify_gpfdists_cert

-added guc definition to list of gucs
-added link to guc from appropriate topics.

PR for 5X_STABLE
Will be ported to MAIN

* docs:  verify_gpfdists_cert guc updates
-add SSL exceptions that are ignored
-other minor edits

* docs: guc verify_gpfdists_cert - fix typos

* docs - remove guc category section and doc files from admin guide

* add server config param categories to ref guide left nav

-Add  GUC optimizer_enable_associativity
-Add limitation for ONLY table name qualifier  (fallback to planner)

* docs: add real-time query metrics GUCs to reference

* Edits to clarify commerical Pivotal GPDB

* Remove duplicate gp_log_interconnect entry

* docs: add GUC gp_ignore_error_table

* docs: updated ditamap for gp_ignore_error_table

* docs: gp_ignore_error_table GUC - updates based on review comments.

In the upcoming PostgreSQL 9.0 merge, validating the custom variable
classes was causing grief in with the new plpgsql.variable_conflict GUC.
If you set that GUC after loading plpgsql in the QD, plpgsql migh still not
be loaded in QE processes. If the GUC was changed in the QD, the QD would
dispatch the new value to QE processes, which threw an error because the
'plpgsql' custom variable class was not defined.

In principle, we would have the same problem with any other GUC added by
a loadable module.

To fix,  cherry-pick upstream commit from 9.2, to remove the GUC and the
validation of custom variable classes altogether. Might as well do that
now, rather than make some temporary work-arounds, since it's a sensible
change that we'll get eventually from upstream anyway.

Upstream commit:

commit 1a00c0ef
Author: Tom Lane <tgl@sss.pgh.pa.us>
Date:   Tue Oct 4 12:36:18 2011 -0400

    Remove the custom_variable_classes parameter.

    This variable provides only marginal error-prevention capability (since
    it can only check the prefix of a qualified GUC name), and the consensus
    is that that isn't worth the amount of hassle that maintaining the setting
    creates for DBAs.  So, let's just remove it.

    With this commit, the system will silently accept a value for any qualified
    GUC name at all, whether it has anything to do with any known extension or
    not.  (Unqualified names still have to match known built-in settings,
    though; and you will get a WARNING at extension load time if there's an
    unrecognized setting with that extension's prefix.)

    There's still some discussion ongoing about whether to tighten that up and
    if so how; but if we do come up with a solution, it's not likely to look
    anything like custom_variable_classes.

gp_hashagg_respill_bias has been dead for close to 10 years while
gp_hashjoin_bloomfilter was a leftover from 1fd4d7ee.
gp_hashagg_rewrite_limit was deprecated close to 10 years ago and
made into a no-op.

gp_fault_action and the consumers of gp_backup_directIO* GUCs were
removed with the recent filespaces removal.

Since persistent tables were removed, these were not used for anything.

Now that we use the upstream implementation for window functions, the
'gp_enable_sequential_window_plans' and 'gp_idf_deduplicate' GUCs are no
longer.

* docs: optimizer_join_order guc

* Implement suggested edits

* Note iteractions with other params; correct inaccurate statement.

* Clarify this is a GPORCA guc

* docs: add orca guc optimizer_join_arity_for_associativity_commutativity

will be backported to 5X_STABLE

* fix typo

* DOCS: SELECT - Add RECURSIVE keyword to WITH clause

* docs: recursive CTE - add experimental designation. Add GUC gp_recursive_cte_prototype

* docs: updated recursive CTE docs based on review comments.

* DOCS: gucs for interconnect debugging

* docs: port fixes from COPY ON SEGMENT review.

* DOCS: New GUC gp_enable_segment_copy_checking. COPY ON SEGMENT changes

* docs: remove draft comment

* docs: Edited text based on review comments. Reorganized notes on COPY ... ON SEGMENT information.

* docs: clean up typos found in review.

* Add log_temp_files guc

* Add subnav log_temp_files to ditamap

* Add mention of spill files and pg_log

* Add ignore_checksum_failure GUC to reference

* Changes for review comments

* Promote embedded warning to a tagged warning

* Add heap checksums to gpinitsystem ref and GUC reference

* Replace heap_checksums with data_checksomes

* GPDB DOCS - new GUCs from 4.3.x and mdcache

* Typo fixes

* typo

* updates based or review comments.