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Thread: DB wal file disabled --_Query

DB wal file disabled --_Query

From

jayakumar s

Date:

13 November, 22:15:49

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]$

Re: DB wal file disabled --_Query

From

"David G. Johnston"

Date:

13 November, 22:21:44

On Wed, Nov 13, 2024 at 9:16 AM jayakumar s <kumardba27.postgresql@gmail.com> wrote:

postgres=# select name,setting from pg_settings where name like 'archive%';
name | setting
-----------------+------------
archive_command | (disabled)

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

David J.

Re: DB wal file disabled --_Query

From

Adrian Klaver

Date:

13 November, 22:24:47

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.
> 
> 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)

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.
"




> 
> 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]$

-- 
Adrian Klaver
adrian.klaver@aklaver.com

Re: DB wal file disabled --_Query

From

jayakumar s

Date:

14 November, 15:14:09

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?

On Wed, Nov 13, 2024 at 9:54 PM Adrian Klaver <adrian.klaver@aklaver.com> wrote:

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.
>
> 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)

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.
"

>
> 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]$

--
Adrian Klaver
adrian.klaver@aklaver.com

Re: DB wal file disabled --_Query

From

"David G. Johnston"

Date:

14 November, 20:02:48

On Thursday, November 14, 2024, jayakumar s <kumardba27.postgresql@gmail.com> wrote:

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?

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.