本篇文章為大家展示了怎么在postgresql 中查看pg_wal目錄下的xlog文件大小，內容簡明扼要并且容易理解，絕對能使你眼前一亮，通過這篇文章的詳細介紹希望你能有所收獲。
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 ./
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：
答：使用 initdb 調整WAL文件大小。
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
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 最后訪問時間戳(linux:最近訪問) 、
– 3 modification 最后修改時間戳(linux:最近更改–) 、
– 4 change 最后文件狀態改變時間戳（只支持 Unix 平臺）(linux:最近改動) 、
– 5 creation 文件創建時間戳（只支持 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/archivelogwith 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
;上述內容就是怎么在postgresql 中查看pg_wal目錄下的xlog文件大小，你們學到知識或技能了嗎？如果還想學到更多技能或者豐富自己的知識儲備，歡迎關注億速云行業資訊頻道。
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