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Date: Mon, 29 Apr 2024 08:34:40 -0700
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Subject: Re: Need help to make space on my database
To: Cocam' server <cocamserver@gmail.com>
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From: Adrian Klaver <adrian.klaver@aklaver.com>
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On 4/29/24 08:04, Cocam' server wrote:

When replying use Reply All to include the mailing list
Ccing list

>  > How much current free space do you have available on the disk?
> as we speak, I only have 6 GB available on the machine running the server
> 
>  > Did you VACUUM FULL a table at a time or all of them at once?
> I tried to make a VACUUM FULL. I also tried on the biggest tables (200 
> Mb and +) but not on all of them

Did the above work for each table?

Have you done something like?:

select relname, n_dead_tup from pg_stat_all_tables where relname = 
'<table_name>';

to see if there any dead tuples to clean out.

Or if you use the contrib extension pgstattuple:

https://www.postgresql.org/docs/current/pgstattuple.html

then:

SELECT * FROM pgstattuple('<table_name>');

This returns something like:

-[ RECORD 1 ]------+--------
table_len          | 3940352
tuple_count        | 4310
tuple_len          | 3755414
tuple_percent      | 95.31
dead_tuple_count   | 0
dead_tuple_len     | 0
dead_tuple_percent | 0
free_space         | 124060
free_percent       | 3.15


> 
> The two biggest are these:
>   state_groups_state | 5475 MB
>   event_json | 2328 MB
> 
> (I'd particularly like to make room on these two tables, which take up 
> the most space)
> 
> By the way, excuse me if I make a few mistakes (especially when 
> replying), this is the first time I've used Postgres community support 
> directly
> 
> 
> Le lun. 29 avr. 2024 à 16:37, Adrian Klaver <adrian.klaver@aklaver.com 
> <mailto:adrian.klaver@aklaver.com>> a écrit :
> 
>     On 4/29/24 07:33, Cocam' server wrote:
> 
>     Please reply to list also
>     Ccing list
> 
>      > No, the aim is also to reallocate free space to the system for
>     the other
>      > tasks it performs.(That's why I said I'd like it returned to the OS)
> 
>     You led with:
> 
>     "I need help to make space on my database".
> 
>     How much current free space do you have available on the disk?
> 
>     Did you VACUUM FULL a table at a time or all of them at once?
> 
>     What are the individual tables sizes?
> 
>      >
>      > Le lun. 29 avr. 2024 à 16:19, Adrian Klaver
>     <adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>
>      > <mailto:adrian.klaver@aklaver.com
>     <mailto:adrian.klaver@aklaver.com>>> a écrit :
>      >
>      >     On 4/29/24 06:45, Cocam' server wrote:
>      >      > Hello.
>      >      >
>      >      > I need help to make space on my database. I have tables
>     that are
>      >     several
>      >      > GB in size. I used to use the VACUUM FULL VERBOSE command; but
>      >     now, this
>      >      > command is too greedy in free space to be used and I'm looking
>      >     for a way
>      >      > to make free space (given back to the OS)
>      >      >
>      >      > Thanks in advance to everyone who responds
>      >
>      >     Per
>      >
>      > https://www.postgresql.org/docs/current/sql-vacuum.html
>     <https://www.postgresql.org/docs/current/sql-vacuum.html>
>      >     <https://www.postgresql.org/docs/current/sql-vacuum.html
>     <https://www.postgresql.org/docs/current/sql-vacuum.html>>
>      >
>      >     "VACUUM reclaims storage occupied by dead tuples. In normal
>     PostgreSQL
>      >     operation, tuples that are deleted or obsoleted by an update
>     are not
>      >     physically removed from their table; they remain present
>     until a VACUUM
>      >     is done. Therefore it's necessary to do VACUUM periodically,
>     especially
>      >     on frequently-updated tables.
>      >
>      >     <...>
>      >
>      >     Plain VACUUM (without FULL) simply reclaims space and makes it
>      >     available
>      >     for re-use. This form of the command can operate in parallel with
>      >     normal
>      >     reading and writing of the table, as an exclusive lock is not
>     obtained.
>      >     However, extra space is not returned to the operating system
>     (in most
>      >     cases); it's just kept available for re-use within the same
>     table.
>      >     "
>      >
>      >     So a regular VACUUM should work if all you want to do is give the
>      >     database the ability to recycle the vacuumed tuple space.
>      >
>      >     --
>      >     Adrian Klaver
>      > adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>
>     <mailto:adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>>
>      >
> 
>     -- 
>     Adrian Klaver
>     adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>
> 

-- 
Adrian Klaver
adrian.klaver@aklaver.com