pgsql: Fix tuple routing in cases where tuple descriptors don't match.

Fix tuple routing in cases where tuple descriptors don't match.

The previous coding failed to work correctly when we have a
multi-level partitioned hierarchy where tables at successive levels
have different attribute numbers for the partition key attributes. To
fix, have each PartitionDispatch object store a standalone
TupleTableSlot initialized with the TupleDesc of the corresponding
partitioned table, along with a TupleConversionMap to map tuples from
the its parent's rowtype to own rowtype. After tuple routing chooses
a leaf partition, we must use the leaf partition's tuple descriptor,
not the root table's. To that end, a dedicated TupleTableSlot for
tuple routing is now allocated in EState.

Amit Langote

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/2ac3ef7a01df859c62d0a02333b646d65eaec5ff

Modified Files
--------------
src/backend/catalog/partition.c | 74 ++++++++++++++++++++++++++++------
src/backend/commands/copy.c | 31 +++++++++++++-
src/backend/executor/nodeModifyTable.c | 27 +++++++++++++
src/include/catalog/partition.h | 7 ++++
src/include/nodes/execnodes.h | 3 ++
src/test/regress/expected/insert.out | 37 +++++++++++++++++
src/test/regress/sql/insert.sql | 26 ++++++++++++
7 files changed, 190 insertions(+), 15 deletions(-)