pg确定一张表最后被使用的时间

create or replace function table_file_access_info(

IN schemaname text,IN tablename text,OUT last_access timestamp with time zone,

OUT last_change timestamp with time zone

) LANGUAGE plpgsql AS $func$

DECLARE

     tabledir text;

     filenode text;

BEGIN

     SELECT regexp_replace(current_setting('data_directory') || '/' || pg_relation_filepath(c.oid), pg_relation_filenode(c.oid) || '$',''),pg_relation_filenode(c.oid)

INTO tabledir,filenode

from pg_class c

join pg_namespace ns

on c.relnamespace=ns.oid

and c.relname=tablename

and ns.nspname=schemaname;

raise notice 'tabledir:% - filenode : %',tabledir,filenode;

select max((pg_stat_file(tabledir || filename)).access),

     max((pg_stat_file(tabledir || filename)).modification)

     INTO last_access, last_change

from pg_ls_dir(tabledir) as filename

where filename ~ ('^' || filenode || '([.]?[0-9]+)?$');

END;

$func$;

调用该函数：

select  table_file_access_info('public','test');   --大概时间

输出示例：

postgres=# select  table_file_access_info('public','test');
NOTICE:  tabledir:/home/postgres/datalm/base/13241/ - filenode : 16392
               table_file_access_info                
-----------------------------------------------------
 ("2017-03-23 17:26:02+08","2017-03-23 17:35:16+08")
(1 row)

postgres=#