Обсуждение: pgsql: Allow UPDATE to move rows between partitions.

Allow UPDATE to move rows between partitions.

When an UPDATE causes a row to no longer match the partition
constraint, try to move it to a different partition where it does
match the partition constraint.  In essence, the UPDATE is split into
a DELETE from the old partition and an INSERT into the new one.  This
can lead to surprising behavior in concurrency scenarios because
EvalPlanQual rechecks won't work as they normally did; the known
problems are documented.  (There is a pending patch to improve the
situation further, but it needs more review.)

Amit Khandekar, reviewed and tested by Amit Langote, David Rowley,
Rajkumar Raghuwanshi, Dilip Kumar, Amul Sul, Thomas Munro, Álvaro
Herrera, Amit Kapila, and me.  A few final revisions by me.

Discussion: http://postgr.es/m/CAJ3gD9do9o2ccQ7j7+tSgiE1REY65XRiMb=yJO3u3QhyP8EEPQ@mail.gmail.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/2f178441044be430f6b4d626e4dae68a9a6f6cec

Modified Files
--------------
contrib/file_fdw/input/file_fdw.source  |   1 +
contrib/file_fdw/output/file_fdw.source |   2 +
doc/src/sgml/ddl.sgml                   |  24 +-
doc/src/sgml/ref/update.sgml            |  13 +-
doc/src/sgml/trigger.sgml               |  23 ++
src/backend/commands/copy.c             |  40 +-
src/backend/commands/trigger.c          |  52 ++-
src/backend/executor/execPartition.c    | 241 ++++++++++-
src/backend/executor/nodeModifyTable.c  | 583 +++++++++++++++++++++------
src/backend/nodes/copyfuncs.c           |   2 +
src/backend/nodes/equalfuncs.c          |   1 +
src/backend/nodes/outfuncs.c            |   3 +
src/backend/nodes/readfuncs.c           |   1 +
src/backend/optimizer/path/allpaths.c   |   4 +-
src/backend/optimizer/plan/createplan.c |   4 +
src/backend/optimizer/plan/planner.c    |  19 +-
src/backend/optimizer/prep/prepunion.c  |  28 +-
src/backend/optimizer/util/pathnode.c   |   4 +
src/include/executor/execPartition.h    |  34 +-
src/include/nodes/execnodes.h           |   4 +-
src/include/nodes/plannodes.h           |   1 +
src/include/nodes/relation.h            |   3 +
src/include/optimizer/pathnode.h        |   1 +
src/include/optimizer/planner.h         |   3 +-
src/test/regress/expected/update.out    | 681 ++++++++++++++++++++++++++++++--
src/test/regress/sql/update.sql         | 458 +++++++++++++++++++--
src/tools/pgindent/typedefs.list        |   1 +
27 files changed, 1957 insertions(+), 274 deletions(-)

On Sat, Jan 20, 2018 at 2:03 AM, Robert Haas <rhaas@postgresql.org> wrote:
> Allow UPDATE to move rows between partitions.
>

+    If an <command>UPDATE</command> on a partitioned table causes a row to move
+    to another partition, it will be performed as a <command>DELETE</command>
+    from the original partition followed by an <command>INSERT</command> into
+    the new partition. In this case, all row-level <literal>BEFORE</literal>
+    <command>UPDATE</command> triggers and all row-level
+    <literal>BEFORE</literal> <command>DELETE</command> triggers are fired on
+    the original partition.

Do we need to maintain triggers related behavior for logical
replication?  In logical replication, we use ExecSimpleRelationDelete
to perform Delete operation which is not aware of this special
behavior (execute before update trigger for this case).

-- 
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com