Обсуждение: BUG #15950: pg_freespace.avail is 0

The following bug has been logged on the website:

Bug reference:      15950
Logged by:          Daniel Adeniji
Email address:      daniel_adeniji@hotmail.com
PostgreSQL version: 11.4
Operating system:   Windows 10
Description:

Issued the query pasted below :-
===============================

with cteSetting
(
      name
    , setting
)

as
(
    select 
              name
            , setting::integer
            
    from   pg_catalog.pg_settings
    
    where  name = 'block_size'
)
SELECT 

          tblN.nspname 
            as "schema"

        , tblC.relname

        , avg(tblC.relpages)::int
            as relpages

        , avg(tblC.reltuples)::int
            as reltuples

        , count(*) as cnt

        , pg_size_pretty
            (
                cast
                (
                    avg(tblPGFS.avail) as bigint
                )
            ) 
            as "Av. freespace size"

        /*
             max(cteSBS.setting)
            as "blockSize"
        */
        
        , round
            (
                100 
                    * avg
                    (
                        tblPGFS.avail
                    )
                    /
                    ( 
                        avg(cteSBS.setting)::int
                    )
                ,2
            ) as "Av. freespace ratio"        

FROM pg_catalog.pg_class tblC

join pg_catalog.pg_namespace tblN

    on tblC.relnamespace = tblN.oid

inner join pg_freespace(tblC.oid) tblPGFS

    on TRUE

inner join cteSetting cteSBS
    on cteSBS.name = 'block_size'

where   tblC.relkind = 'r'

and     tblN.nspname not in

            (
                  'information_schema'
                , 'pg_catalog'

            )

GROUP BY

          tblN.nspname 

        , tblC.relname

ORDER BY

          tblN.nspname 

        , tblC.relname

;


Result :-
=========

1) pg_freespace.avail is 0

PostgreSQL :- Create free pages in Table

https://learningintheopen.org/2019/08/12/postgresql-create-freepages-in-table/.