Re: tables meta data collection

On Wed, Mar 03, 2021 at 01:20:51AM +0000, Nagaraj Raj wrote:
> 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. 

Looks like you should join information_schema.columns *before*
pg_catalog.pg_description, otherwise the columns view has nothing to join to
unless the column has a description.
...or you could use FULL OUTER JOIN on the columns view.

>  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 |

--
Justin Pryzby
System Administrator
Telsasoft
+1-952-707-8581