最近在整理postgresql数据库的表、列的备注信息时，用到了如下的sql

表、视图、分区表的备注

with tmp_tab as (
    select pc.oid as ooid,pn.nspname,pc.*
      from pg_class pc
           left outer join pg_namespace pn
                        on pc.relnamespace = pn.oid
      where 1=1
       and pc.relkind in ('r','v','m','f','p')
       and pn.nspname not in ('pg_catalog','information_schema') -- select pn.oid, pn.* from pg_namespace pn where 1=1
       and pn.nspname not like 'pg_toast%'
       /*and pc.oid not in (
          select inhrelid
            from pg_inherits
       )*/
    order by pc.relname
),tmp_desc as (
   select pd.*
     from pg_description pd
    where 1=1
      and pd.objsubid = 0 --objsubid 对于一个表列上的一个注释，这里是列号（objoid和classoid指表本身）。对所有其他对象类型，此列为0。
      --and pd.objoid=168605
)
select t0.*,
       case when t0.relkind in ('r','p')
                 then 'comment on table '||t0.nspname||'.'||t0.relname||' is '''||coalesce(t0.description,'')||''';' 
            when t0.relkind='v' 
                 then 'comment on view '||t0.nspname||'.'||t0.relname||' is '''||coalesce(t0.description,'')||''';' 
        end as table_description
  from (
		select tab.nspname,
		       tab.relname,
		       tab.relkind,
		       de.description
		  from tmp_tab tab
		       left outer join tmp_desc de
		                    on tab.ooid = de.objoid 
		 where 1=1    
		) t0
 where 1=1
   --and t0.description is not null
order by t0.nspname,t0.relname   
;

列的备注

with tmp_tab as (
    select pc.oid as ooid,pn.nspname,pc.*
      from pg_class pc
           left outer join pg_namespace pn
                        on pc.relnamespace = pn.oid
      where 1=1
       and pc.relkind in ('r','v','m','f','p')
       and pn.nspname not in ('pg_catalog','information_schema') -- select pn.oid, pn.* from pg_namespace pn where 1=1
       and pn.nspname not like 'pg_toast%'
       /*
       and pc.oid not in (
          select inhrelid
            from pg_inherits
       )*/
    order by pc.relname
),tmp_col as (
   select pa.*
     from pg_attribute pa
    where 1=1
      --and pa.attrelid = 168605
      and pa.attisdropped = false
      and pa.attname not in (
      'tableoid',
      'cmax',
      'xmax',
      'cmin',
      'xmin',
      'ctid'
      )
),tmp_desc as (
   select pd.*
     from pg_description pd
    where 1=1
      and pd.objsubid <> 0 --objsubid 对于一个表列上的一个注释，这里是列号（objoid和classoid指表本身）。对所有其他对象类型，此列为0。
      --and pd.objoid=168605
)
select t0.*,
       'comment on COLUMN '||t0.nspname||'.'||t0.relname||'.'||t0.attname||' is '''||coalesce(t0.description,'')||''';' as column_description
  from (
		select tab.nspname,
		       tab.relname,
		       tc.attname,
		       tc.attnum,
		       de.description
		  from tmp_tab tab
		       left outer join tmp_col tc
		                    on tab.ooid = tc.attrelid
		       left outer join tmp_desc de
		                    on tc.attrelid = de.objoid and tc.attnum = de.objsubid
       ) t0
 where 1=1
   --and t0.description is not null
order by t0.nspname,t0.relname, t0.attnum
;

参考:
http://postgres.cn/docs/9.6/catalog-pg-class.html
http://postgres.cn/docs/9.6/catalog-pg-attribute.html
http://postgres.cn/docs/9.6/catalog-pg-description.html