Re: Allow table AMs to define their own reloptions

Hello!

+dummy_table_am behaves like a heap table but accepts a different
+set of reloptions:
+
+ - "fillfactor" (inherited from the core heap registration via
+ add_reloption_to_kind)

+bool
+RelationHasStdRdOptions(Relation relation)
+{
+ if (relation->rd_options == NULL)
+ return false;
+ if (relation->rd_tableam == NULL)
+ return false;
+ return relation->rd_tableam->amoptions == NULL;
+}

dummy_table_am seems to accept but ignore fillfactor options with
this, which based on the documentation above seem unintended?

CREATE TABLE heap_ff10 (a int) WITH (fillfactor=10);
CREATE TABLE dummy_ff10 (a int) USING dummy_table_am WITH (fillfactor=10);

INSERT INTO heap_ff10 SELECT generate_series(1,200000);
INSERT INTO dummy_ff10 SELECT generate_series(1,200000);

SELECT relname, relpages,
pg_size_pretty(pg_relation_size(oid)) AS size
FROM pg_class
WHERE relname IN ('heap_ff10','dummy_ff10')
ORDER BY relname;
relname | relpages | size
------------+----------+---------
dummy_ff10 | 885 | 7080 kB
heap_ff10 | 9091 | 71 MB
(2 rows)

Also it isn't critical for the current tests, but it doesn't seem to
support text columns, so that contradicts the generic behaves like
heap claim a bit:

CREATE TABLE t_txt (a int, b text) USING dummy_table_am;
ERROR: only heap AM is supported