I have a table, when given the below query, gives 20 GB in size, I truncate the table and give the below query again, it still shows 20GB, I thought when you truncate the table resources are released and no space occupied, why am I still seeing size in GB being populated although I truncated ?
select OWNER,TABLE_NAME, round((NUM_ROWS*a.avg_row_len)/1024/1024/1024,2) SIZE_IN_GB
from dba_tables a
where round((NUM_ROWS*a.avg_row_len)/1024/1024/1024,2) > 5
and a.owner = 'xxx'
ORDER BY 3 DESC;