I'm using a hosted PostgreSQL database where I don't have shell access. Is there a query I can use to check the current WAL log size?

1 Answer 1


If you have superuser access, you can use:

select * 
from pg_ls_dir('pg_xlog');

which will return one row for each file in the directory pg_xlog. As the size for a WAL segment is fixed, you can easily calculate the total size by multiplying the number of rows by 16MB:

select count(*) * pg_size_bytes(current_setting('wal_segment_size')) as total_size
from pg_ls_dir('pg_xlog') as t(fname)
where fname <> 'archive_status';

Alternatively you can use pg_stat_file() to return information about the files:

select sum((pg_stat_file('pg_wal/'||fname)).size) as total_size
from pg_ls_dir('pg_xlog') as t(fname);

Starting with Postgres 10 you can use:

select sum(size) 
from pg_ls_waldir()
  • 1
    Pg 10 also provides for pg_current_wal_flush_lsn(), pg_current_wal_insert_lsn(), pg_current_wal_lsn() which you can feed to pg_walfile_name() Commented Dec 6, 2017 at 22:27
  • 1
    please note the 16MB size is the default but could be configured to be different
    – Luke404
    Commented Feb 9, 2021 at 13:42
  • @Luke404: good point, I have changed the query.
    – user1822
    Commented Feb 9, 2021 at 13:47
  • 4
    what's the unit for each query? Bytes?
    – Alex
    Commented Mar 18, 2021 at 0:59
  • @Alex it seems that for the last one it is indeed bytes. Commented Aug 10, 2021 at 6:39

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