Message-ID: <c8ec7a00-c5c6-48e2-ae25-14a02278d52b@ya.ru>
Date: Fri, 20 Sep 2024 14:32:48 +0300
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From: Olleg <splarv@ya.ru>
Subject: Dependencies on the system view
To: pgsql-general@postgresql.org
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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 here will be a troubles 
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;
-- 
Olleg