At Sun, 01 Nov 2020 21:05:29 -0500, Tom Lane <t...@sss.pgh.pa.us> wrote in
> Kyotaro Horiguchi <horikyota....@gmail.com> writes:
> > We cannot reach there with ev_action == NULL since it comes from a
> > non-nullable column. Since most of the other columns has an assertion
> > that !isnull, I think we should do the same thing for ev_action (and
> > ev_qual). SPI_getvalue() returns C-NULL for SQL-NULL (or for some
> > other unexpected situations.).
>
> Isn't the comment just above there wrong?
>
> /* these could be nulls */
>
> I wonder just when that became outdated.
Mmm. I investigated that.
At the very beginning of CREATE RULE (d31084e9d1, 1996), InsertRule()
did the following.
> template = "INSERT INTO pg_rewrite \
>(rulename, ev_type, ev_class, ev_attr, action, ev_qual, is_instead) VALUES \
>('%s', %d::char, %d::oid, %d::int2, '%s'::text, '%s'::text, \
> '%s'::bool);";
> if (strlen(template) + strlen(rulname) + strlen(actionbuf) +
> strlen(qualbuf) + 20 /* fudge fac */ > RULE_PLAN_SIZE) {
> elog(WARN, "DefineQueryRewrite: rule plan string too big.");
> }
> sprintf(rulebuf, template,
> rulname, evtype, eventrel_oid, evslot_index, actionbuf,
> qualbuf, is_instead);
Doesn't seem that ev_qual and ev_action can be NULL. The same
function in the current converts action list to string using
nodeToSTring so NIL is converted into '<>', which is not NULL.
So I think ev_action cannot be null from the beginning of the history
unless the columns is modified manually. ev_qual and ev_action are
marked as non-nullable (9b39b799db, in 2018). They could be null if we
modified that columns nullable then set NULL, but that could happen on
all other columns in pg_rewite catalog, which are Assert(!null)ed.
Although ev_action cannot be a empty list using SQL interface. So we
can get rid of the case list_length(action) == 0, but I'm not sure
it's worth doing (but the attaches does..).
regards.
--
Kyotaro Horiguchi
NTT Open Source Software Center
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 6c656586e8..120b8869ea 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -4763,15 +4763,15 @@ make_ruledef(StringInfo buf, HeapTuple ruletup, TupleDesc rulettc,
Assert(!isnull);
is_instead = DatumGetBool(dat);
- /* these could be nulls */
fno = SPI_fnumber(rulettc, "ev_qual");
ev_qual = SPI_getvalue(ruletup, rulettc, fno);
+ Assert(ev_qual != NULL);
fno = SPI_fnumber(rulettc, "ev_action");
ev_action = SPI_getvalue(ruletup, rulettc, fno);
- if (ev_action != NULL)
- actions = (List *) stringToNode(ev_action);
-
+ Assert(ev_action != NULL);
+ actions = (List *) stringToNode(ev_action);
+
ev_relation = table_open(ev_class, AccessShareLock);
/*
@@ -4819,10 +4819,8 @@ make_ruledef(StringInfo buf, HeapTuple ruletup, TupleDesc rulettc,
generate_relation_name(ev_class, NIL) :
generate_qualified_relation_name(ev_class));
- /* If the rule has an event qualification, add it */
- if (ev_qual == NULL)
- ev_qual = "";
- if (strlen(ev_qual) > 0 && strcmp(ev_qual, "<>") != 0)
+ Assert(strlen(ev_qual) > 0);
+ if (strcmp(ev_qual, "<>") != 0)
{
Node *qual;
Query *query;
@@ -4875,6 +4873,7 @@ make_ruledef(StringInfo buf, HeapTuple ruletup, TupleDesc rulettc,
appendStringInfoString(buf, "INSTEAD ");
/* Finally the rules actions */
+ Assert(list_length(actions) > 0);
if (list_length(actions) > 1)
{
ListCell *action;
@@ -4893,10 +4892,6 @@ make_ruledef(StringInfo buf, HeapTuple ruletup, TupleDesc rulettc,
}
appendStringInfoString(buf, ");");
}
- else if (list_length(actions) == 0)
- {
- appendStringInfoString(buf, "NOTHING;");
- }
else
{
Query *query;
