This patch removes codegen wholesale from Greenplum.

In addition to reverting the commits involving codegen, we also removed
miscellaneous references to the feature and GUC.

The following commits from 5.0.0 were reverted (topologically ordered):

f38c9064 Support avg aggregate function in codegen
87dcae4c Capture and print error messages from llvm::verifyFunction
65137540 libgpcodegen assert() overrides use GPDB Assert()
81d378b4 GenerateExecVariableList calls regular slot_getattr when the code generation of the latter fails
05a28211 Update Google Test source path used by codegen
22a35fcc Call ereport when code generating float operators
79517271 Support overflow checks for doubles.
b5373a1e Fix codegen unittest link problem
7a1a98c9 Print filename and lineno in codegened CreateElog
58eda293 Fix wrong virtual tuple check in codegened slot_getattr
bc6faa08 Set llvm_isNull_ptr to false when the result of codegened expression evaluation is not null
8bbbd63f Enhance codegened advance_aggregates with support for null attributes
e1fd6072 Abort code generation of expression evaluation trees with unsupported ExprState types
509460ee Support null attributes in codegen expression evaluation framework
739d978d Move enrollment of codegened ExecVariableList to ExecInitNode
c05528d1 Fix CHECK_SYMBOL_DEFINED macro in CMakeLists.txt
12cfd7bd Support offset calculation when there is null in the tuple and codegen is enabled
40a2631e Use slot_getattr wrapper function for regular version.(#1194)
613e9fbb Revert "Fix codegen issue by moving slot_getattr to heaptuple.c similar to"
ee03f799 Fix cpplint error on advance aggregate
2a65b0aa Fix slot function nullptr issue in expr eval.
3107fc0e Fix for !(expr1 & expr2) and hasnull logic in slot_getatrr codegen.
c940c7f6 Fix codegen issue by moving slot_getattr to heaptuple.c similar to Postgres.
c8125736 Introduce guc to enable/disable all generator.
a4f39507 Ensure that codegen unittests pass with GCC 6.2.0 (#1177)
682d0b28 Allow overriding assert() functionality in libgpcodegen in DEBUG mode
3209258a Organize codegen source files and unit tests
d2ba88a9 Fix codegen unittests using DatumCastGenerator
020b71a5 Generate code for COUNT aggregate function
0eeec886 Fixing codegen related bugs in InitializeSupportedFunction
41055352 Rewrite PGGenericFuncGenerator to support variable number of types
e5318b6b Add AdvanceAggregatesCodegenEnroll mock function
87521715 Codegen advance_aggregates for SUM transition function
2043d95b Use string messages in codegened slot_getattr fallback block
f160fa5a Add new GUC to control Codegen Optimization level.
697ffc1a Fix cpplint errors
c5e3aed4 Support Virtual Tuples and Memtuples in SlotGetAttrCodegen
5996aaa7 Keep a reference to the CodegenManager in code generators
6833b3c2 Remove unused header and just include what you use in codegen
ab1eda87 Allow setting codegen guc to ON only if code generation is supported by the build
dcd40712 Use PGFuncGeneratorInfo to codegen pg functions
83869d1c Replace dynamic_cast with dyn_cast for llvm objects
23007017 Decide what to generate for ExecEvalExpr based on PlanState
387d8ce8 Add EXPLAIN CODEGEN to print generated IR to the client
c4a9bd27 Introduce Datum to cpp cast, cpp type to Datum cast  and normal cast.(#944)
66158dfd Record external function names for useful debugging
adab9120 Support variable length attributes in SlotGetAttrCodegen.
335e09aa Proclaim that the codegen'ed version of generated functions are called in debug build
50fd9140 Fix cpplint errors
88a04412 Use ExprTreeGeneratorInfo for expression tree generation.
3b4af3bb Split code generation of ExecVariableList from slot_getattr
8cd9ed9f Support <= operator for date/timestamp data types and some minor refactors.
e4dccf46 Implement InlineFunction to force inline at call site
71170942 Mock postmaster.o for codegen_framework_unittest.t
09f00581 Codegen expressions that contain plus, minus and mul operators on float8 data types
d7fb2f6d Fix codegen unittests on Linux and various compiler warnings while building codegen.
45f2aa96 Fix test and update coding style This closes #874
1b26fbfc Enrolled targetlist for scan and aggregate
ebd1d014 Enhance codegen framework to support arbitrary expr tree
ec626ce6 Generate and enroll naive ExecEvalExpr in Scan's quals
1186001e Revert "Create naive code-generated version of ExecQual"
6f928a65 Replace RegisterExternalFunction with GetOrRegisterExternalFunction using an unordered_map in codegen_utils
6ae0085b Move ElogWrapper to GpCodegenUtils.
d3f80b45 Add verifyfunction for generated llvm function.
7bcf094a Fix codegen compiler error with 8.3 merge
aae0ad3d Create naive code-generated version of ExecQual
dce266ad Minor code quality fixes in src/backend/codegen
d281f340 Support null attributes in code generated ExecVariableList
82fd418e Address a number of cpplint errors in codegen_utils_unittest.cc
887aa48d Add check for CodegenUtils::GetType for bool arrays
bb9b92c6 Enhance Base Codegen to do clean up when generation fails
b9ef5e3f Fix build error for Annotated types
a5cfefd9 Add support for array types in codegen_utils.
2b883384 Fix static_assert call
7b75d9ea This commit  generates code for code path: ExecVariableList > slot_getattr > _slot_getsomeattrs > slot_deform_tuple. This code path is executed during scan in simple select queries that do not have a where clause (e.g., select bar from foo;).
6d0a06e8 Fix CodeGen typos and CodeGeneratorManagerCreate function signature in gpcodegen_mock.c
4916a606 Add support for registering vararg external functions with codegen utils.
ae4a7754 Integrate codegen framework and make simple external call to slot deform tuple. This closes #649
ee5fb851 Renaming code_generator to codegen_utils and CodeGenerator to CodegenUtils. This closes #648
88e9baba Adding GPDB code generation utils
Signed-off-by: NJesse Zhang <sbjesse@gmail.com>
Signed-off-by: NMelanie Plageman <mplageman@pivotal.io>
Signed-off-by: NSambitesh Dash <sdash@pivotal.io>

These were added in GPDB to encapsulate RelFileNode and persistent table
information. But persistent tables are no more, so there is no reason to
differ from upstream.

To reduce merge conflicts as we start to merge with upstream again.

Also add some comments, based on the descriptions of the original bugs
that were fixed.

These are no longer used for anything.

With persistent tables removed there are no more consumers of this
API, so remove it.

The change in index.c is a behavioral change. The behavior on reindexing
shared catalogs now matches upstream again. The rest is just removal of
dead code.

This test file is currently unused altogether. That's another issue we
should do something about, but let's at least remove these clearly obsolete
queries from it.

These changes were made obsolete by the removal of all the cdbdump code
(commit 8922315e).

A long time ago, they were disabled, because the GIN code had not been
modified to work with file replication. Now with WAL replication, there's
no reason to not support them.

After finding a match in semijoin mode, arrange to advance to
the next outer tuple not next inner tuple after returning the
current match. The node->mj_MatchedOuter is always false here,
there is no need to check it.

Author: Max Yang <myang@pivotal.io>

contrib/bufferedtest depends on LZJB code which was removed long
before the open sourcing of Greenplum, and contrib/varblocktest
hasn't built in a long time due to the Makefile being wonky. Since
noone has missed these tools, remove them rather than keeping dead
code around.

They were not testing anything interesting anymore. Per discussion on
gpdb-dev mailing list.

Discussion: https://groups.google.com/a/greenplum.org/d/msg/gpdb-dev/gq07ixYkTqk/ehLfByeIAAAJ

In the first cut of the walreplication work, I left out the part that
drops a segfile during AO compaction, because there was no
straightforward native PostgreSQL function to drop just a single segfile.
However, that leads to a massive disk space leak, as the space freed by
VACUUM on an AO table is not reclaimed, until the same segment number is
used again for further insertions, so we clearly must do something about
that.

Instead of dropping the segfile altogether, like we used to, truncate the
file to 0 bytes. Mostly because that's more expedient to do, as we have
the functions to do that and to WAL-log that, whereas code to fully remove
just a single segfile doesn't exist. But if you squint a bit, you could
even call that an optimization: it saves the overhead of recreating the
file again, if you load more data to it later.

Pointed out by Coverity.

As Coverity pointed out, 'pelem' has already been dereferenced in the
function, and hence it can never be NULL here. And indeed it should never
be NULL.

With 'prule', we explicitly checked for NULL earlier in the function.

This test keeps failing in CI intermittently, needs to be looked into as seems
hitting the assertion currently
"Unexpected internal error (postmaster.c:5328)","FailedAssertion(""!(CountChildren(0x0001|0x0002) == 0)"", File: ""postmaster.c"", Line: 5328)"

Once postmaster cleanup PR is done will revisit the test.

The IDENTIFICATION stanza in the source files is of questionable
usefulness, but unexpanded CVS keywords that never existed in the
codebase where the expansion happened are even less useful.
Replace with the filepath to make these headers consistent with
upstream.

A PL/JAVA NULL point reference has been reported by coverity scan.
The issue is located in guc.c for a pljava guc option
"pljava_classpath_insecure" and fixed in this commit.

tuple store which just advances current position by N instead of getting
tuple N times.

Author: Max Yang <myang@pivotal.io>

Since ICW is a very longrunning process, attempt to reduce time
consumption by reducing overhead during testing while keeping the
test constant (coverage not reduced).

Avoid dropping/recreating underlying test tables when not required,
reduce the number of partitions in some cases and skip pointless
drops for objects we know doesn't exist. In total this shaves about
30-40 seconds off an ICW run on my local machine, mileage may vary.

Make sure that we are able to exchnage in an external partition, and
also ensure that truncation doesn't recurse into the ext partition.

This backports the below commit which moved from the source timezone
file to the newly introduced compact format.

  commit 097b24cea68ac167a82bb617eb1844c8be4eaf24
  Author: Tom Lane <tgl@sss.pgh.pa.us>
  Date:   Sat Nov 25 15:30:11 2017 -0500

    Replace raw timezone source data with IANA's new compact format.

    Traditionally IANA has distributed their timezone data in pure source
    form, replete with extensive historical comments.  As of release 2017c,
    they've added a compact single-file format that omits comments and
    abbreviates command keywords.  This form is way shorter than the pure
    source, even before considering its allegedly better compressibility.
    Hence, let's distribute the data in that form rather than pure source.

    I'm pushing this now, rather than at the next timezone database update,
    so that it's easy to confirm that this data file produces compiled zic
    output that's identical to what we were getting before.

    Discussion: https://postgr.es/m/1915.1511210334@sss.pgh.pa.us

The timezone data in Greenplum are from the base version of
PostgreSQL that the current version of Greenplum is based on.
This cause issues since it means we are years behind on tz
changes that have happened. This pulls in the timezone data
and code from PostgreSQL 10.1 with as few changes to Greenplum
as possible to minimize merge conflicts. The goal is to gain
data rather than features, and for Greenplum for each release
to be able to stay current with the iana tz database as it is
imported into upstream PostgreSQL.

This removes a Greenplum specific test for the Yakutsk timezone
as it was made obsolete by upstream tz commit 1ac038c2c3f25f72.

pg_ctl and gpstart appear to be running simultaneously, because we're
not waiting for pg_ctl to finish before moving to the next call.
(subprocess.Popen() doesn't return the process's return code -- it
returns a Popen instance.)

cs_walrep_2 in the master pipeline is currently failing roughly 50% of
the time due to a crash during test_negative. Let's see if this helps at
all.