$ unzip session_exec-master.zip 
$ cd session_exec-master/
$ make pg_config=/opt/pgsql/bin/pg_config
$ make pg_config=/opt/pgsql/bin/pg_config install

session_preload_libraries='session_exec'
session_exec.login_name='login'

$ sudo systemctl restart postgresql-12

create table t_login
(
login_time timestamp(3) with time zone --插入時(shí)間,
user_name text --數(shù)據(jù)庫登錄用戶,
flag int4 --標(biāo)志位，0代表過期數(shù)據(jù)，1代表正常狀態(tài)數(shù)據(jù)
);

$ cd /opt/postgresql-12.5/contrib/file_fdw
$ make && make install

create extension file_fdw;
CREATE SERVER pglog FOREIGN DATA WRAPPER file_fdw;

CREATE FOREIGN TABLE postgres_log( 
 log_time timestamp(3) with 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 pglog 
OPTIONS ( program 'find /opt/pg_log_5432 -type f -name "*.csv" -mtime -1 -exec cat {} \;', format 'csv' );

$ psql -Upostgres
WARNING: function "login()" does not exist
psql (12.5)
Type "help" for help.

create or replace function login() returns void as $$
declare
res text;
c1 timestamp(3) with time zone;
begin

--獲取當(dāng)前日志中最新時(shí)間
select login_time 
from public.t_login 
where flag = 0 
order by login_time 
desc limit 1 
into c1; 

 --將最新的數(shù)據(jù)插入t_login表
insert into public.t_login 
select log_time,user_name 
from public.postgres_log 
where command_tag='authentication' 
and error_severity= 'FATAL' 
and log_time > c1;

update public.t_login set flag = 1 where login_time > c1; 

--檢查登錄失敗次數(shù)是否大于3，若大于3則鎖定用戶
for res in select user_name from public.t_login where flag = 1 group by user_name having count(*) >=3 
loop
--鎖定用戶
EXECUTE format('alter user %I nologin',res); 
--斷開當(dāng)前被鎖定用戶會話
EXECUTE 'select pg_catalog.pg_terminate_backend(pid) from pg_catalog.pg_stat_activity where usename=$1' using res; 
raise notice 'Account % is locked!',res;
end loop;
end;
$$ language plpgsql strict security definer set search_path to 'public';

create user test1 encrypted password 'XXX';

$ psql -h192.168.137.11 -Utest1 postgres
Password for user test1: 
psql: error: FATAL: password authentication failed for user "test1"

select * from postgres_log where command_tag='authentication' and error_severity= 'FATAL';

insert into t_login select log_time,user_name,0
 from postgres_log 
 where command_tag='authentication' 
 and error_severity= 'FATAL';

postgres=# select * from t_login;
  login_time  | user_name | flag 
-------------------------+-----------+------
 2021-02-08 06:24:47.101 | test1  | 0
 2021-02-08 06:25:16.581 | test1  | 1
 2021-02-08 06:25:18.429 | test1  | 1
(3 rows)

[postgres@node11 ~]$ psql
NOTICE: Account test1 is locked!
psql (12.5)
Type "help" for help.

postgres=# select * from t_login;
  login_time  | user_name | flag 
-------------------------+-----------+------
 2021-02-08 06:45:38.017 | test1  | 0
 2021-02-08 06:45:58.809 | test1  | 1
 2021-02-08 06:45:58.809 | test1  | 1
 2021-02-08 06:46:08.116 | test1  | 1
 2021-02-08 06:46:11.986 | test1  | 1
(5 rows)

update t_login set flag = 0 where user_name='test1' and flag=1;