创建 extension

CREATE EXTENSION file_fdw;

创建 server

CREATE SERVER file_fdw_server FOREIGN DATA WRAPPER file_fdw;

获取最新日志文件

select t00.*
from (
    select t1.file,
           t1.file_ls,
           (pg_stat_file(t1.file)).modification as last_update_time,
           round( ((pg_stat_file(t1.file)).size)/1024/1024*1.0,1) as log_size_mb
      from (select dir||'/'||pg_ls_dir(t0.dir) as file,
                   pg_ls_dir(t0.dir) as file_ls
              from ( select setting as dir from pg_settings where name='log_directory'
                    ) t0
            ) t1 
     where 1=1
     order by (pg_stat_file(file)).modification desc
    ) t00
where 1=1
  and t00.file_ls like '%.csv'
limit 1  
;

创建外部表

select name,setting 
from pg_settings where name ~ 'log';


CREATE FOREIGN TABLE pglog_current (  
  log_time timestamp(3) without time zone,  
  user_name text,  
  database_name text,  
  process_id integer,  
  connection_from text,  
  session_id text,  
  session_line_num bigint, 
  command_tag text, 

  session_start_time timestamp with time zone,  
  virtual_transaction_id text,  
  transaction_id bigint,  
  error_severity text,  
  sql_state_code text,  
  message text,  
  detail text,  
  hint text,  
  internal_query text,  
  internal_query_pos integer,  
  context text,  
  query text,  
  query_pos integer,  
  location text,  
  application_name text
 ) 
server file_fdw_server 
options(filename '/var/log/postgresql/postgresql-2017-08-29.csv',format 'csv')
;

查询外部表

select count(1)
from pglog_current
where 1=1
;

select plc.*
from pglog_current plc
where 1=1
order by plc.log_time 
;

可以和德哥一样写个存储过程来判断和创建。

参考：
http://blog.163.com/digoal@126/blog/static/16387704020121023105322442/
https://www.postgresql.org/docs/current/static/sql-createforeigntable.html
https://www.postgresql.org/docs/current/static/file-fdw.html