tables meta data collection

From: Nagaraj Raj <nagaraj(dot)sf(at)yahoo(dot)com>
To: Pgsql Performance <pgsql-performance(at)lists(dot)postgresql(dot)org>
Subject: tables meta data collection
Date: 2021-03-03 01:20:51
Message-ID: 591365510.2330079.1614734451782@mail.yahoo.com
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Hi Everyone,
I was trying to collect table metadata with a description; the use case is that I need to show all columns of the tables whether it has the description or not. 
I tried the below query, but it only gives column details that have a description and ignore others if not. 

Postgres 11 | db<>fiddle

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Postgres 11 | db<>fiddle

Free online SQL environment for experimenting and sharing.
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create table test(id int);create table test1(id int Primary key );comment on column test.id is 'Test descr';

 SELECT c.table_schema,c.table_name,c.column_name,case     when c.domain_name is not null then c.domain_name    when c.data_type='character varying' THEN 'character varying('||c.character_maximum_length||')'    when c.data_type='character' THEN 'character('||c.character_maximum_length||')'     when c.data_type='numeric' THEN 'numeric('||c.numeric_precision||','||c.numeric_scale||')'    else c.data_typeend as data_type,c.is_nullable, (select 'Y' from information_schema.table_constraints tcojoin information_schema.key_column_usage kcu      on kcu.constraint_name = tco.constraint_name     and kcu.constraint_schema = tco.constraint_schema     and kcu.constraint_schema = c.table_schema and kcu.table_name = c.table_name and kcu.column_name = c.column_namewhere tco.constraint_type = 'PRIMARY KEY' ) as is_in_PK,(select distinct 'Y' from information_schema.table_constraints tcojoin information_schema.key_column_usage kcu      on kcu.constraint_name = tco.constraint_name     and kcu.constraint_schema = tco.constraint_schema     and kcu.constraint_schema = c.table_schema and kcu.table_name = c.table_name and kcu.column_name = c.column_namewhere tco.constraint_type = 'FOREIGN KEY' ) as is_in_FK,pgd.description

FROM pg_catalog.pg_statio_all_tables as st  Left outer join pg_catalog.pg_description pgd on (pgd.objoid=st.relid)  left outer join information_schema.columns c on (pgd.objsubid=c.ordinal_position    and  c.table_schema=st.schemaname and c.table_name=st.relname)where c.table_name='test'order by c.table_schema,c.table_name,c.ordinal_position; 

expected formate is :

| table_schema | table_name | column_name | data_type | is_nullable | is_in_pk | is_in_fk | description |

any suggestions?
Thanks,Rj

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