pgsql: Handle INSERT .. ON CONFLICT with partitioned tables

Handle INSERT .. ON CONFLICT with partitioned tables

Commit eb7ed3f30634 enabled unique constraints on partitioned tables,
but one thing that was not working properly is INSERT/ON CONFLICT.
This commit introduces a new node keeps state related to the ON CONFLICT
clause per partition, and fills it when that partition is about to be
used for tuple routing.

Author: Amit Langote, Álvaro Herrera
Reviewed-by: Etsuro Fujita, Pavan Deolasee
Discussion: https://postgr.es/m/20180228004602.cwdyralmg5ejdqkq@alvherre.pgsql

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/555ee77a9668e3f1b03307055b5027e13bf1a715

Modified Files
--------------
doc/src/sgml/ddl.sgml                         |  15 --
doc/src/sgml/ref/insert.sgml                  |   8 +
src/backend/catalog/partition.c               |  88 ++++++++--
src/backend/executor/execMain.c               |   4 +
src/backend/executor/execPartition.c          | 233 ++++++++++++++++++++++++--
src/backend/executor/nodeModifyTable.c        |  74 ++++++--
src/backend/parser/analyze.c                  |   7 -
src/include/catalog/partition.h               |   1 +
src/include/nodes/execnodes.h                 |  22 ++-
src/include/nodes/nodes.h                     |   1 +
src/test/regress/expected/insert_conflict.out | 108 ++++++++++--
src/test/regress/expected/triggers.out        |  33 ++++
src/test/regress/sql/insert_conflict.sql      |  95 +++++++++--
src/test/regress/sql/triggers.sql             |  33 ++++
14 files changed, 638 insertions(+), 84 deletions(-)