postgresql 如何查看pg_wal目錄下xlog文件總大小

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當然如果你登錄服務器所在主機，直接在$PGDAT/pg_wal下執行：

du -h --max-depth=1 ./

可以得到。

#du -h --max-depth=1 ./
4.0K  ./archive_status
193M  ./

如果通過客戶端怎麼做呢？

答案：pg_ls_waldir()函數。pg_ls_waldir()是pg 10.0引入的函數，可以輸出數據庫WAL目錄的所有文件。

postgres=# select sum(size) from pg_ls_waldir();   
  sum  
-----------
 201326592
(1 row)

單位是byte，所以當前pg_wal的xlog日志總大小為201326592/1024/1024=192M。

也可以使用：

postgres=# select count(*) from pg_ls_waldir();
 count 
-------
  12
(1 row)

12表示wal日志文件個數，總大小12*16=192M。

16表示單個wal日志文件大小，單位MB，WAL 日志文件大小默認為16MB。

bonus：

1、怎麼調整單個wal日志文件大小？

答：使用 initdb 調整WAL文件大小。

2、pg_ls_logdir() 也是pg10.0版本引入的函數，輸出數據庫日志目錄的所有文件。

postgres=# select * from pg_ls_logdir();
        name        | size  |   modification   
----------------------------------+---------+------------------------
 postgresql-2020-04-28_092020.log | 2277343 | 2020-04-29 11:34:56+08
 postgresql-2020-04-28_092020.csv | 140050 | 2020-04-29 11:34:56+08

3、如何列出/data文件夾中的文件？

答：pg_ls_dir

postgres=# select pg_ls_dir('/data');
   pg_ls_dir    
----------------------

補充：postgresql 查看wal生成頻率和大小

–wal 文件生成數量

–linux ls –full-time stat filename

–pg_stat_file返回一個記錄，其中包含

– 1 size 文件尺寸

– 2 access 最後訪問時間戳(linux:最近訪問) 、

– 3 modification 最後修改時間戳(linux:最近更改–) 、

– 4 change 最後文件狀態改變時間戳（隻支持 Unix 平臺）(linux:最近改動) 、

– 5 creation 文件創建時間戳（隻支持 Windows）

– 6 isdir 一個boolean指示它是否為目錄 isdir

– select * from pg_stat_file('/var/lib/postgresql/9.1/main/pg_xlog/0000000200000BBB000000A9');
– /var/lib/postgresql/9.1/main/pg_xlog
– /var/log/postgresql
– /mnt/nas_dbbackup/archivelog
with tmp_file as (
  select t1.file,
      t1.file_ls,
      (pg_stat_file(t1.file)).size as size,
      (pg_stat_file(t1.file)).access as access,
      (pg_stat_file(t1.file)).modification as last_update_time,
      (pg_stat_file(t1.file)).change as change,
      (pg_stat_file(t1.file)).creation as creation,
      (pg_stat_file(t1.file)).isdir as isdir
   from (select dir||'/'||pg_ls_dir(t0.dir) as file,
          pg_ls_dir(t0.dir) as file_ls
       from ( select '/var/lib/postgresql/9.1/main/pg_xlog'::text as dir
           --需要修改這個物理路徑
           --select '/mnt/nas_dbbackup/archivelog'::text as dir
           --select setting as dir from pg_settings where name='log_directory'
          ) t0
      ) t1 
   where 1=1
   order by (pg_stat_file(file)).modification desc
) 
select to_char(date_trunc('day',tf0.last_update_time),'yyyymmdd') as day_id,
    sum(case when date_part('hour',tf0.last_update_time) >=0 and date_part('hour',tf0.last_update_time) <24 then 1 else 0 end) as wal_num_all,
    sum(case when date_part('hour',tf0.last_update_time) >=0 and date_part('hour',tf0.last_update_time) <1 then 1 else 0 end) as wal_num_00_01,
    sum(case when date_part('hour',tf0.last_update_time) >=1 and date_part('hour',tf0.last_update_time) <2 then 1 else 0 end) as wal_num_01_02,
    sum(case when date_part('hour',tf0.last_update_time) >=2 and date_part('hour',tf0.last_update_time) <3 then 1 else 0 end) as wal_num_02_03,
    sum(case when date_part('hour',tf0.last_update_time) >=3 and date_part('hour',tf0.last_update_time) <4 then 1 else 0 end) as wal_num_03_04,
    sum(case when date_part('hour',tf0.last_update_time) >=4 and date_part('hour',tf0.last_update_time) <5 then 1 else 0 end) as wal_num_04_05,
    sum(case when date_part('hour',tf0.last_update_time) >=5 and date_part('hour',tf0.last_update_time) <6 then 1 else 0 end) as wal_num_05_06,
    sum(case when date_part('hour',tf0.last_update_time) >=6 and date_part('hour',tf0.last_update_time) <7 then 1 else 0 end) as wal_num_06_07,
    sum(case when date_part('hour',tf0.last_update_time) >=7 and date_part('hour',tf0.last_update_time) <8 then 1 else 0 end) as wal_num_07_08,
    sum(case when date_part('hour',tf0.last_update_time) >=8 and date_part('hour',tf0.last_update_time) <9 then 1 else 0 end) as wal_num_08_09,
    sum(case when date_part('hour',tf0.last_update_time) >=9 and date_part('hour',tf0.last_update_time) <10 then 1 else 0 end) as wal_num_09_10,
    sum(case when date_part('hour',tf0.last_update_time) >=10 and date_part('hour',tf0.last_update_time) <11 then 1 else 0 end) as wal_num_10_11,
    sum(case when date_part('hour',tf0.last_update_time) >=11 and date_part('hour',tf0.last_update_time) <12 then 1 else 0 end) as wal_num_11_12,
    sum(case when date_part('hour',tf0.last_update_time) >=12 and date_part('hour',tf0.last_update_time) <13 then 1 else 0 end) as wal_num_12_13,
    sum(case when date_part('hour',tf0.last_update_time) >=13 and date_part('hour',tf0.last_update_time) <14 then 1 else 0 end) as wal_num_13_14,
    sum(case when date_part('hour',tf0.last_update_time) >=14 and date_part('hour',tf0.last_update_time) <15 then 1 else 0 end) as wal_num_14_15,
    sum(case when date_part('hour',tf0.last_update_time) >=15 and date_part('hour',tf0.last_update_time) <16 then 1 else 0 end) as wal_num_15_16,
    sum(case when date_part('hour',tf0.last_update_time) >=16 and date_part('hour',tf0.last_update_time) <17 then 1 else 0 end) as wal_num_16_17,
    sum(case when date_part('hour',tf0.last_update_time) >=17 and date_part('hour',tf0.last_update_time) <18 then 1 else 0 end) as wal_num_17_18,
    sum(case when date_part('hour',tf0.last_update_time) >=18 and date_part('hour',tf0.last_update_time) <19 then 1 else 0 end) as wal_num_18_19,
    sum(case when date_part('hour',tf0.last_update_time) >=19 and date_part('hour',tf0.last_update_time) <20 then 1 else 0 end) as wal_num_19_20,
    sum(case when date_part('hour',tf0.last_update_time) >=20 and date_part('hour',tf0.last_update_time) <21 then 1 else 0 end) as wal_num_20_21,
    sum(case when date_part('hour',tf0.last_update_time) >=21 and date_part('hour',tf0.last_update_time) <22 then 1 else 0 end) as wal_num_21_22,
    sum(case when date_part('hour',tf0.last_update_time) >=22 and date_part('hour',tf0.last_update_time) <23 then 1 else 0 end) as wal_num_22_23, 
    sum(case when date_part('hour',tf0.last_update_time) >=23 and date_part('hour',tf0.last_update_time) <24 then 1 else 0 end) as wal_num_23_24
from tmp_file tf0
where 1=1
 and tf0.file_ls not in ('archive_status')
group by to_char(date_trunc('day',tf0.last_update_time),'yyyymmdd')
order by to_char(date_trunc('day',tf0.last_update_time),'yyyymmdd') desc
;

以上為個人經驗，希望能給大傢一個參考，也希望大傢多多支持WalkonNet。如有錯誤或未考慮完全的地方，望不吝賜教。

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