Column numbers, if trigger is column-specific;
otherwise an empty array

tgargs

bytea

Argument strings to pass to trigger, each
NULL-terminated

tgqual

text

Expression tree (in nodeToString() representation) for the
trigger's WHEN condition, or
null if none

Currently, column-specific triggering is supported only for
UPDATE events, and so tgattr is relevant only for that event type.
tgtype might contain bits for other
event types as well, but those are presumed to be table-wide
regardless of what is in tgattr.

Note: When tgconstraint is nonzero, tgconstrrelid, tgconstrindid, tgdeferrable, and tginitdeferred are largely redundant with
the referenced pg_constraint
entry. However, it is possible for a non-deferrable trigger
to be associated with a deferrable constraint: foreign key
constraints can have some deferrable and some non-deferrable
triggers.

Note:pg_class.relhastriggers must be true if a
table has any triggers in this catalog.