On Fri, Sep 20, 2024 at 7:32 AM Olleg <splarv@xxxxx> wrote:
Hi all.
One of our programmer created a view based on the system view. I tried
to explain him, that he created a dependency from the ordinary database
to the system object and this is a bad idea. But he is not smart enough.
So I need a guru opinion. Is this permissible or will here be a trouble
with, for instance, pg_upgrade?
CREATE OR REPLACE VIEW public.all_tables
AS SELECT n.nspname AS schemaname,
c.relname AS tablename,
pg_get_userbyid(c.relowner) AS tableowner,
c.reltuples AS num_rows,
c.relkind,
CASE c.relkind
WHEN 'f'::"char" THEN 'Foreign table'::text
WHEN 'r'::"char" THEN 'Relation'::text
WHEN 'i'::"char" THEN 'Index'::text
WHEN 'S'::"char" THEN 'Sequence'::text
WHEN 't'::"char" THEN 'TOAST'::text
WHEN 'v'::"char" THEN 'View'::text
WHEN 'm'::"char" THEN 'Materialized view'::text
WHEN 'c'::"char" THEN 'Composite type'::text
WHEN 'p'::"char" THEN 'Partitioned table'::text
WHEN 'I'::"char" THEN 'partitioned Index'::text
ELSE NULL::text
END AS rel_type,
c.relpersistence,
CASE c.relpersistence
WHEN 'p'::"char" THEN 'permanent'::text
WHEN 'u'::"char" THEN 'unlogged'::text
WHEN 't'::"char" THEN 'temporary'::text
WHEN 'c'::"char" THEN 'constant'::text
ELSE NULL::text
END AS persistence,
t.spcname AS tablespace,
c.relhasindex AS hasindexes,
c.relhasrules AS hasrules,
c.relhastriggers AS hastriggers
FROM pg_class c
LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
LEFT JOIN pg_tablespace t ON t.oid = c.reltablespace;
1. pg_upgrade will throw an error if a column in one of those catalog tables is removed. Version release notes should mention whether columns are dropped; you'll just have to drop that view beforehand, and create a new version afterwards, possibly modifying any pg/plsql. No big deal, honestly; just something to keep in mind.
2. The query will become incomplete/wrong when new relkind and relpersistence values are added, necessitating an updated version. Again, not a big deal, and just something to keep in mind.
Thus, I see no problem with that sort of view. Heck, I've made similar views; they're all over my cron jobs. (I think it should not be in public -- my views all go in the "dba" schema -- but that's a different issue.)
Death to <Redacted>, and butter sauce.
Don't boil me, I'm still alive.
<Redacted> crustacean!
