Horton

Re: UPDATE of partition key

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Amit Khandekar <amitdkhan.pg@gmail.com>
Cc: Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>, pgsql-hackers <pgsql-hackers@postgresql.org>, Thomas Munro <thomas.munro@enterprisedb.com>
Date: 2017-11-06T19:03:29Z
Lists: pgsql-hackers 
On Wed, Oct 25, 2017 at 11:40 AM, Amit Khandekar <amitdkhan.pg@gmail.com> wrote:
> Below I have addressed the remaining review comments :

The changes to trigger.c still make me super-nervous.  Hey THOMAS
MUNRO, any chance you could review that part?

+       /* The caller must have already locked all the partitioned tables. */
+       root_rel = heap_open(root_relid, NoLock);
+       *all_part_cols = NULL;
+       foreach(lc, partitioned_rels)
+       {
+               Index           rti = lfirst_int(lc);
+               Oid                     relid = getrelid(rti, rtables);
+               Relation        part_rel = heap_open(relid, NoLock);
+
+               pull_child_partition_columns(part_rel, root_rel, all_part_cols);
+               heap_close(part_rel, NoLock);

I don't like the fact that we're opening and closing the relation here
just to get information on the partitioning columns.  I think it would
be better to do this someplace that already has the relation open and
store the details in the RelOptInfo.  set_relation_partition_info()
looks like the right spot.

+void
+pull_child_partition_columns(Relation rel,
+                                                        Relation parent,
+                                                        Bitmapset **partcols)

This code has a lot in common with is_partition_attr().  I'm not sure
it's worth trying to unify them, but it could be done.

+ * 'num_update_rri' : number of UPDATE per-subplan result rels. For INSERT,

Instead of " : ", you could just write "is the".

+                * For Updates, if the leaf partition is already present in the
+                * per-subplan result rels, we re-use that rather than
initialize a
+                * new result rel. The per-subplan resultrels and the
resultrels of
+                * the leaf partitions are both in the same canonical
order. So while

It would be good to explain the reason.  Also, Updates shouldn't be
capitalized here.

+                               Assert(cur_update_rri <= update_rri +
num_update_rri - 1);

Maybe just cur_update_rri < update_rri + num_update_rri, or even
current_update_rri - update_rri < num_update_rri.

Also, +1 for Amit Langote's idea of trying to merge
mt_perleaf_childparent_maps with mt_persubplan_childparent_maps.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

Commits

  1. Avoid referencing off the end of subplan_partition_offsets.

  2. Allow UPDATE to move rows between partitions.

  3. Remove useless lookup of root partitioned rel in ExecInitModifyTable().

  4. Factor error generation out of ExecPartitionCheck.

  5. Minor preparatory refactoring for UPDATE row movement.

  6. Simplify and encapsulate tuple routing support code.

  7. Avoid coercing a whole-row variable that is already coerced.

  8. Use ResultRelInfo ** rather than ResultRelInfo * for tuple routing.

  9. Make RelationGetPartitionDispatchInfo expand depth-first.

  10. Expand partitioned tables in PartDesc order.

  11. Use a real RT index when setting up partition tuple routing.

  12. Fix transition tables for partition/inheritance.

  13. Fix confusion about number of subplans in partitioned INSERT setup.

  14. Prevent BEFORE triggers from violating partitioning constraints.

  15. Fire per-statement triggers on partitioned tables.

  16. Fix reporting of violations in ExecConstraints, again.

  17. Don't scan partitioned tables.

  18. Allow FDWs to push down quals without breaking EvalPlanQual rechecks.