[PATCH] Add pretty formatting to pg_get_triggerdef

[Philip Alger]

Hello Hackers,

Currently, `pg_get_triggerdef` includes a "pretty" flag, but it does not
actually format the `CREATE TRIGGER` statement in a "pretty" way. Unlike
`pg_get_viewdef`, `pg_get_ruledef`, and `pg_get_indexdef`, the purpose of
pretty formatting has been to remove the schema name so it can be used by
the `\d` psql comment to display triggers associated with a view or table,
as shown below:

postgres=# \d main_table
             Table "public.main_table"
 Column |  Type   | Collation | Nullable | Default
--------+---------+-----------+----------+---------
 a      | integer |           |          |
 b      | integer |           |          |
Indexes:
    "main_table_a_key" UNIQUE CONSTRAINT, btree (a)
Triggers:
    foofoo AFTER INSERT ON main_table FOR EACH STATEMENT EXECUTE FUNCTION
trigger_func('foo_bar')
    foo_bar BEFORE INSERT ON main_table FOR EACH STATEMENT EXECUTE FUNCTION
trigger_func('foo_bar')
    bar_fooAFTER DELETE ON main_table FOR EACH ROW WHEN ((old.a = 123))
EXECUTE FUNCTION trigger_func('foo_bar')

This patch introduces true pretty formatting to `pg_get_triggerdef`.
Additionally, it creates a new function specifically for the `\d` psql
command, as that command requires schema removal and a single line
statement.

With this patch, when the `pretty` parameter is set to `true`,
`pg_get_triggerdef` now displays a formatted output, consistent with
`pg_get_viewdef`, `pg_get_ruledef`, and `pg_get_indexdef`:

postgres=# select pg_get_triggerdef(12345, true);
                pg_get_triggerdef
--------------------------------------------------
 CREATE TRIGGER some_trig_foobar AFTER UPDATE    +
     ON some_t                                   +
     FOR EACH ROW                                +
     WHEN (NOT new.some_col)                     +
     EXECUTE FUNCTION dummy_update_func('foobar')
(1 row)

When the `pretty` flag is `false`, the function's behavior remains
unchanged from the original implementation:

postgres=# select pg_get_triggerdef(47901, false);

 pg_get_triggerdef

---------------------------------------------------------------------------------------------------------------------------------------------------
 CREATE TRIGGER some_trig_foobar AFTER UPDATE ON public.some_t FOR EACH ROW
WHEN ((NOT new.some_col)) EXECUTE FUNCTION dummy_update_func('foobar')
(1 row)


-- 
Best,
Phil Alger

v1-0001-Add-pretty-formatting-to-pg_get_triggerdef.patch
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