Subject: DB wal file disabled --_Query

From: jayakumar s <[email-masked]>
Date: Wed, 13 Nov 2024 21:45:49 +0530

Hi Team,

We have disabled walfile ion database level. While I do manual switch wal
file generating in wal file location.

Here is my question if we disable it. Walfile won't generate am i correct?

Kindly clarify my doubts.

postgres=# select name,setting from pg_settings where name like 'archive%';
      name       |  setting
-----------------+------------
 archive_command | (disabled)
 archive_mode    | off
 archive_timeout | 0
(3 rows)

postgres=#

postgres=# SELECT pg_switch_wal();
 pg_switch_wal
---------------
 D/9D000000
(1 row)

[postgres@xxxxxxxxx pg_wal]$ ls -lrt
total 81920
drwx------. 2 postgres postgres        6 Oct 13  2020 archive_status
-rw-------. 1 postgres postgres 16777216 Nov 13 20:47
000000010000000D0000009F
-rw-------. 1 postgres postgres 16777216 Nov 13 20:50
000000010000000D000000A0
-rw-------. 1 postgres postgres 16777216 Nov 13 20:51
000000010000000D000000A1
-rw-------. 1 postgres postgres 16777216 Nov 13 21:02
000000010000000D0000009D
-rw-------. 1 postgres postgres 16777216 Nov 13 21:02
000000010000000D0000009E
[postgres@# pg_wal]$

---

From: "David G. Johnston" <[email-masked]>
Date: Wed, 13 Nov 2024 09:21:44 -0700

> postgres=# select name,setting from pg_settings where name like 'archive%';

You cannot disable WAL.  What is disabled here is copying the WAL that is
produced to an archive.  IOW, backing up WAL.

David J.

---

From: Adrian Klaver <[email-masked]>
Date: Wed, 13 Nov 2024 08:24:47 -0800

On 11/13/24 08:15, jayakumar s wrote:
> Hi Team,
> 
> We have disabled walfile ion database level. While I do manual switch 
> wal file generating in wal file location.
> 

The above is disabling the archiving of WAL files to another location. 
WAL will still be written to pg_wal.

What are you trying to achieve?

You can  specify individual tables be UNLOGGED as shown here:

https://www.postgresql.org/docs/current/sql-createtable.html

"UNLOGGED

     If specified, the table is created as an unlogged table. Data 
written to unlogged tables is not written to the write-ahead log (see 
Chapter 28), which makes them considerably faster than ordinary tables. 
However, they are not crash-safe: an unlogged table is automatically 
truncated after a crash or unclean shutdown. The contents of an unlogged 
table are also not replicated to standby servers. Any indexes created on 
an unlogged table are automatically unlogged as well.

     If this is specified, any sequences created together with the 
unlogged table (for identity or serial columns) are also created as 
unlogged.
"

-- 
Adrian Klaver
[email-masked]

---

From: jayakumar s <[email-masked]>
Date: Thu, 14 Nov 2024 14:44:09 +0530

Hi All,

Archive mode is already disabled. If more wal files will generate fs also
reached 100 percent based on application data load.

As updated archive enabled or disabled. Will any state wall file that
will be generate correct?

---

From: "David G. Johnston" <[email-masked]>
Date: Thu, 14 Nov 2024 07:02:48 -0700

> will be generate correct?

WAL files are removed once they are no longer needed by the system.  If
they are not being removed you have an issue you need to debug to figure
out why they are staying around.

David J.