Count no. of files in pg_xlog or pg_wal directory
SELECT COUNT(*) FROM pg_ls_dir('pg_xlog') WHERE pg_ls_dir ~ '^[0-9A-F]{24}';
postgres=# SELECT COUNT(*) FROM pg_ls_dir('pg_wal') WHERE pg_ls_dir ~ '^[0-9A-F]{24}';
count
-------
61
Find Current WAL LSN
postgres=# select pg_current_wal_lsn();
pg_current_wal_lsn
--------------------
3/A0007BC8
(1 row)
Find LSN File Name into WAL
postgres=# select pg_walfile_name('3/A0007BC8');
pg_walfile_name
--------------------------
0000000100000003000000A0
(1 row)
Check PostgreSQL pg_wal / pg_xlog Directory
root@mlt352-ubuntu:/opt/PostgreSQL/10/data/pg_wal# ls -lth
total 977M
-rw——- 1 postgres postgres 16M Apr 5 01:42 0000000100000003000000A0
-rw——- 1 postgres postgres 16M Oct 1 2019 0000000100000003000000D8
-rw——- 1 postgres postgres 16M Oct 1 2019 0000000100000003000000CB
-rw——- 1 postgres postgres 16M Oct 1 2019 0000000100000003000000D7