Re: delta relations in AFTER triggers

On Fri, Mar 24, 2017 at 1:14 PM, Thomas Munro
<thomas(dot)munro(at)enterprisedb(dot)com> wrote:
> On Tue, Mar 14, 2017 at 7:51 AM, Kevin Grittner <kgrittn(at)gmail(dot)com> wrote:
>> On Sun, Mar 12, 2017 at 4:08 PM, Thomas Munro
>> <thomas(dot)munro(at)enterprisedb(dot)com> wrote:
>>> I found a new way to break it: run the trigger function so
>>> that the plan is cached by plpgsql, then ALTER TABLE incompatibly,
>>> then run the trigger function again. See attached.
>>
>> [...]
>>
>> I expected that existing mechanisms would have forced re-planning of
>> a trigger function if the table the function was attached to was
>> altered. Either that was a bit "optimistic", or the old TupleDesc
>> is used for the new plan. Will track down which it is, and fix it.
>
> When PlanCacheRelCallback runs, I don't think it understands that
> these named tuplestore RangeTblEntry objects are dependent on the
> subject table. Could that be fixed like this?
>
> @@ -2571,6 +2582,9 @@ extract_query_dependencies_walker(Node *node,
> PlannerInfo *context)
> if (rte->rtekind == RTE_RELATION)
> context->glob->relationOids =
>
> lappend_oid(context->glob->relationOids, rte->relid);
> + else if (rte->rtekind == RTE_NAMEDTUPLESTORE)
> + context->glob->relationOids =
> +
> lappend_oid(context->glob->relationOids, [subject table's OID]);

I'm not sure if this is the right approach and it may have style
issues, but it does fix the crashing in the ALTER TABLE case I
reported: see attached patch which applies on top of your v12.

BTW I had to make the following change to your v12 because of commit b8d7f053:

/*
* initialize child expressions
*/
- scanstate->ss.ps.targetlist = (List *)
- ExecInitExpr((Expr *) node->scan.plan.targetlist,
- (PlanState *) scanstate);
- scanstate->ss.ps.qual = (List *)
- ExecInitExpr((Expr *) node->scan.plan.qual,
- (PlanState *) scanstate);
+ scanstate->ss.ps.qual =
+ ExecInitQual(node->scan.plan.qual, (PlanState *) scanstate);

--
Thomas Munro
http://www.enterprisedb.com