>
> initially pgsql_tmp size was 87 GB and after execution of query it was
> started increasinng beyond 87GBs so yes, pgsql_tmp directory size is
> getting increased while exporting data into csv file.
>
> But once I rolled back the query, pgsql_tmp directory it was back to
> 87 GBs so please help me in telling how do I clean that 87GB of space
> of pgsql_tmp directory.
>
Ideally applications which creates temp table should drop it when no longer needed.
When not dropped, they get dropped automatically when the session which created
them terminates. Looks like in your case both are not happening.
Which is the oldest session still shown as connected?