[Resending with gzip'ed patch this time, I think the last attempt got eaten.]

On Mon, Jul 18, 2011 at 11:15 PM, Robert Haas <robertmh...@gmail.com> wrote:
> On Mon, Jul 18, 2011 at 10:57 PM, Josh Kupershmidt <schmi...@gmail.com> wrote:
>>>> 1.) For now, I'm just ignoring the issue of visibility checks; I
>>>> didn't see a simple way to support these checks \dd was doing:
>>>>
>>>>    processSQLNamePattern(pset.db, &buf, pattern, true, false,
>>>>                          "n.nspname", "p.proname", NULL,
>>>>                          "pg_catalog.pg_function_is_visible(p.oid)");
>>>>
>>>> I'm a bit leery of adding an "is_visible" column into pg_comments, but
>>>> I'm not sure I have a feasible workaround if we do want to keep this
>>>> visibility check. Maybe a big CASE statement for the last argument of
>>>> processSQLNamePattern() would work...
>>>
>>> Yeah... or we could add a function pg_object_is_visible(classoid,
>>> objectoid) that would dispatch to the relevant visibility testing
>>> function based on object type.  Not sure if that's too much of a
>>> kludge, but it wouldn't be useful only here: you could probably use it
>>> in combination with pg_locks, for example.
>>
>> Something like that might work, though an easy escape is just leaving
>> the query style of \dd as it was originally (i.e. querying the various
>> catalogs directly, and not using pg_comments): discussed a bit in the
>> recent pg_comments thread w/ Josh Berkus.
>
> That's another approach.  It seems a bit lame, but...

I went ahead and patched up \dd to display its five object types with
its old-style rooting around in catalogs. I played around again with
the idea of having \dd query pg_comments, but gave up when I realized:

 1. We might not be saving much complexity in \dd's query
 2. Taking the is_system column out was probably good for pg_comments,
but exacerbates point 1.), not to mention the visibility testing that
would have to be done somehow.
 3. The "objname" column of pg_comments is intentionally different
than the "Name" column displayed by \dd; the justification for this
was that \dd's "Name" display wasn't actually useful to recreate the
call to COMMENT ON, but this difference in pg_comments would make it
pretty tricky to keep \dd's "Name" the same
 4. I still would like to get rid of \dd entirely, thus it seems less
important whether it uses pg_comments. It's down to five object types
now; I think that triggers, constraints, and rules could feasibly be
incorporated into \d+ output as Robert suggested upthread, and perhaps
operator class & operator family could get their own backslash
commands.

Some fixes:
 * shuffled the query components in describe.c's objectDescription()
so they're alphabetized by object type
 * untabified pg_comments in system_views.sql to match its surroundings
 * the WHERE d.objsubid = 0 was being omitted in one or two spots,
 * the objects with descriptions coming from pg_shdescription, which
does not have the objsubid column, were using NULL::integer instead of
0, as all the other non-column object types should have. This seemed
undesirable, and counter to what the doc page claimed.
 * fixed up psql's documentation and help string for \dd

Updated patch attached, along with a revised SQL script to make
testing easier. I can add this to the next CF.

Note, there is a separate thread[1] with just the psql changes broken
out, if it's helpful to consider the psql changes separately from
pg_comments. I do need to update the patch posted there with this
latest set of changes.

Josh
--
[1] http://archives.postgresql.org/pgsql-hackers/2011-07/msg00459.php
CREATE SCHEMA myschema;
COMMENT ON SCHEMA myschema IS 'schema comment';

CREATE DOMAIN us_postal_code AS TEXT
CHECK(
   VALUE ~ '^\\d{5}$'
OR VALUE ~ '^\\d{5}-\\d{4}$'
);
COMMENT ON DOMAIN us_postal_code IS 'domain comment';

CREATE DOMAIN uncommented_domain AS TEXT CHECK(true);

COMMENT ON TABLESPACE pg_default IS 'default tablespace';

CREATE TABLE mytbl (a serial PRIMARY KEY, b int);
COMMENT ON TABLE mytbl IS 'example table';
COMMENT ON SEQUENCE mytbl_a_seq IS 'serial sequence';
COMMENT ON COLUMN mytbl.a IS 'column comment';

CREATE TABLE myschema.another_tbl (a int);
ALTER TABLE myschema.another_tbl ADD CONSTRAINT a_chk_con CHECK(a != 0);
COMMENT ON TABLE myschema.another_tbl IS 'another_tbl comment';
COMMENT ON CONSTRAINT a_chk_con ON myschema.another_tbl IS 'constraint comment';

CREATE INDEX myidx ON mytbl (a);
COMMENT ON INDEX myidx IS 'example index';

ALTER TABLE mytbl ADD CONSTRAINT mycon CHECK (b < 100);
COMMENT ON CONSTRAINT mycon ON mytbl IS 'constraint comment';

CREATE VIEW myview AS SELECT * FROM mytbl;
COMMENT ON VIEW myview IS 'view comment';

CREATE TABLE dummy_tbl (a int);

CREATE RULE "myrule" AS
    ON INSERT TO dummy_tbl
    DO INSTEAD NOTHING;

COMMENT ON RULE "myrule" ON dummy_tbl IS 'bogus rule';

CREATE FUNCTION ex_trg_func() RETURNS trigger AS $$
    BEGIN
    	RETURN NEW;
    END;
$$ LANGUAGE plpgsql;

COMMENT ON FUNCTION ex_trg_func() IS 'function comment';

create trigger ex_trg BEFORE INSERT OR UPDATE ON mytbl
  for each row execute procedure ex_trg_func();
  
COMMENT ON TRIGGER ex_trg ON mytbl IS 'example trigger';

CREATE AGGREGATE public.myavg (float8)
(
    sfunc = float8_accum,
    stype = float8[],
    finalfunc = float8_avg,
    initcond = '{0,0,0}'
);

COMMENT ON AGGREGATE public.myavg (float8) IS 'aggregate comment';

CREATE FOREIGN DATA WRAPPER dummy;
CREATE FOREIGN DATA WRAPPER dummy2;
CREATE FOREIGN DATA WRAPPER uncommented_fdw;

COMMENT ON FOREIGN DATA WRAPPER dummy IS 'dummy fdw';
COMMENT ON FOREIGN DATA WRAPPER dummy2 IS 'dummy2 fdw';

CREATE SERVER my_foreign_server FOREIGN DATA WRAPPER dummy;
CREATE SERVER uncommented_server FOREIGN DATA WRAPPER dummy2;
COMMENT ON SERVER my_foreign_server IS 'dummy foreign server';

CREATE FOREIGN TABLE my_foreign_table (a int) SERVER my_foreign_server;
COMMENT ON FOREIGN TABLE my_foreign_table IS 'foreign table comment';

CREATE FOREIGN TABLE uncommented_ft (a int) SERVER my_foreign_server;

CREATE FOREIGN TABLE myschema.my_ft2 (a int) SERVER my_foreign_server;
COMMENT ON FOREIGN TABLE myschema.my_ft2 IS 'another foreign table comment';


CREATE SEQUENCE my_seq;
COMMENT ON SEQUENCE my_seq IS 'sequence comment';

CREATE TYPE compfoo AS (f1 int, f2 text);
COMMENT ON TYPE compfoo IS 'type comment';

-- after intarray contrib extension installed:
CREATE EXTENSION intarray;
COMMENT ON OPERATOR CLASS gist__int_ops USING gist IS 'comment for gist__int_ops';

CREATE OPERATOR FAMILY dummy_opf USING btree;
COMMENT ON OPERATOR FAMILY dummy_opf USING btree IS 'operator family comment';

Attachment: pg_comments.v16.patch.gz
Description: GNU Zip compressed data

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