Can I assume relation would not be invalid during from ExecutorRun to ExecutorEnd

[Andy Fan]

Hi,

During my recent work,  I need some new stuff attached to Relation.  Rather
than adding
some new data structures,  I added it to Relation directly.  Like
relation->balabala.  Then
I initialize it during ExecutorRun,  like  table_tuple_insert.. and
destroy it at ExecutorEnd.

The above solution works based on 2 assumptions at least:
1.  During the ExecutorRun & ExecutorEnd,  the relcache will never by
invalidated, if not
the old relation->balabala will be lost.  I assume this is correct since I
didn't see any places
where we handle such changes in Executor code.
2.  We need to consider the ExuecotRun raised error,  we need to destroy
the balabala resource
as well.  so I added it to the RelationClose function.

So the overall design works like this:

xxx_table_tuple_insert(Relation rel, ...)
{
   if (rel->balabala == NULL)
        rel->balabala = allocate_bala_resource(rel);  // Allocate the
memory xCtx which is under TopTransactionContext.
   do_task_with(rel->balabala);
}

at the end of the executor,  I run

release_bala_resource(Relation rel)
{
   if (rel->balabala == NULL)
         return;
   do_the_real_task();
   MemoryContextDelete(rel->bala->memctx);
   rel->balabala = NULL
}

For the failed cases:

RelationClose(..)
{
   if (RelationHasReferenceCountZero(relation))
         release_bala_resource(relation);
}

Will my suluation work?

-- 
Best Regards
Andy Fan