Обсуждение: How did VACUUM ANALYZE reclaim large TOAST bloat at disk level in PostgreSQL 16?

## pramod gupta (mail2sony2010@gmail.com):

> How was VACUUM ANALYZE able to reclaim such a large amount of space,
> especially for TOAST data?
> 
> Under what conditions does PostgreSQL reclaim disk space without requiring
> VACUUM FULL or CLUSTER?

https://www.postgresql.org/docs/current/routine-vacuuming.html#VACUUM-FOR-SPACE-RECOVERY
"in the special case where one or more pages at the end of a table
become entirely free and an exclusive table lock can be easily obtained"

Regards,
Christoph

-- 
Spare Space

On 1/15/26 08:42, pramod gupta wrote:
> Hello Everyone,
> 
> I am encountering the following error while using the *pg_ai_query* 
> extension.
> 
> /test=# SELECT generate_query('show recent orders', null, 'gemini');
> ERROR:  Query generation failed: No API key available for gemini 
> provider. Please provide API key as parameter or configure it in 
> ~/.pg_ai.config.
> test=#
> test=# SELECT generate_query('show recent orders', null, 
> 'google_ai_studio');
> ERROR:  Query generation failed: API key required. Pass as parameter or 
> set OpenAI, Anthropic, or Gemini API key in ~/.pg_ai.config.
> test=#/
> 
>   have verified all required permissions and confirmed that the 
> configuration is correctly placed; however, I continue to receive the 
> above error when using the *pg_ai.config* file.
> 
> If I execute the query by explicitly passing the API key, it works as 
> expected:
> 
> /select generate_query('I want to count the rows in orders 
> tables','MYAPIKEY','gemini');/
> 
> 
> This works perfectly. I would appreciate guidance on how to configure 
> this so that the API key does not need to be passed explicitly in the 
> query. Please let me know if there is any alternative configuration or 
> recommended approach to achieve this.

It is AI it should know the answer.

That being said.

1) Did you, in the config file, follow the format here?:

https://benodiwal.github.io/pg_ai_query/configuration.html.

2) Is the client you are running the query as in the same location as 
~/.pg_ai.config?


> 
> Thanks in advance.
> Pramod Gupta
>
---------------------------------------------------------------------------------------------------------------------------------------
> 
> On Mon, Dec 29, 2025 at 9:23 PM pramod gupta <mail2sony2010@gmail.com 
> <mailto:mail2sony2010@gmail.com>> wrote:
> 
>     Hello Everyone,
> 
>     We have a table with a total size of ~628 GB, out of which ~601 GB
>     was TOAST data.
>     After running VACUUM ANALYZE on a weekly basis, the table size
>     reduced significantly to ~109 GB, indicating a large amount of bloat
>     removal.
> 
>     I would like to understand:
> 
>     How was VACUUM ANALYZE able to reclaim such a large amount of space,
>     especially for TOAST data?
> 
>     Under what conditions does PostgreSQL reclaim disk space without
>     requiring VACUUM FULL or CLUSTER?
> 
>     Is this behavior expected in PostgreSQL 16, particularly for heavily
>     updated or deleted TOASTed columns?
> 
>     Any insights or documentation references would be greatly appreciated.
> 
>     PostgreSQL version: 16
> 
>     Thanks in advance.
>     Pramod Gupta
> 


-- 
Adrian Klaver
adrian.klaver@aklaver.com

On 1/15/26 09:06, pramod gupta wrote:
Reply to list also
Ccing list

> Hi Adrian,
> 
> Thanks for you quick response, Did in the same way but its not working.

1) Show your configuration.

2) Is the client you are running the query as in the same location as
      ~/.pg_ai.config?

3) Does the Postgres log show anything?
> 
> Regards,
> Pramod Gupta
> 
> On Thu, Jan 15, 2026 at 10:21 PM Adrian Klaver 
> <adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>> wrote:
> 
>     On 1/15/26 08:42, pramod gupta wrote:
>      > Hello Everyone,
>      >
>      > I am encountering the following error while using the *pg_ai_query*
>      > extension.
>      >
>      > /test=# SELECT generate_query('show recent orders', null, 'gemini');
>      > ERROR:  Query generation failed: No API key available for gemini
>      > provider. Please provide API key as parameter or configure it in
>      > ~/.pg_ai.config.
>      > test=#
>      > test=# SELECT generate_query('show recent orders', null,
>      > 'google_ai_studio');
>      > ERROR:  Query generation failed: API key required. Pass as
>     parameter or
>      > set OpenAI, Anthropic, or Gemini API key in ~/.pg_ai.config.
>      > test=#/
>      >
>      >   have verified all required permissions and confirmed that the
>      > configuration is correctly placed; however, I continue to receive
>     the
>      > above error when using the *pg_ai.config* file.
>      >
>      > If I execute the query by explicitly passing the API key, it
>     works as
>      > expected:
>      >
>      > /select generate_query('I want to count the rows in orders
>      > tables','MYAPIKEY','gemini');/
>      >
>      >
>      > This works perfectly. I would appreciate guidance on how to
>     configure
>      > this so that the API key does not need to be passed explicitly in
>     the
>      > query. Please let me know if there is any alternative
>     configuration or
>      > recommended approach to achieve this.
> 
>     It is AI it should know the answer.
> 
>     That being said.
> 
>     1) Did you, in the config file, follow the format here?:
> 
>     https://benodiwal.github.io/pg_ai_query/configuration.html <https://
>     benodiwal.github.io/pg_ai_query/configuration.html>.
> 
>     2) Is the client you are running the query as in the same location as
>     ~/.pg_ai.config?
> 
> 
>      >
>      > Thanks in advance.
>      > Pramod Gupta
>      >
>
---------------------------------------------------------------------------------------------------------------------------------------
>      >
>      > On Mon, Dec 29, 2025 at 9:23 PM pramod gupta
>     <mail2sony2010@gmail.com <mailto:mail2sony2010@gmail.com>
>      > <mailto:mail2sony2010@gmail.com
>     <mailto:mail2sony2010@gmail.com>>> wrote:
>      >
>      >     Hello Everyone,
>      >
>      >     We have a table with a total size of ~628 GB, out of which
>     ~601 GB
>      >     was TOAST data.
>      >     After running VACUUM ANALYZE on a weekly basis, the table size
>      >     reduced significantly to ~109 GB, indicating a large amount
>     of bloat
>      >     removal.
>      >
>      >     I would like to understand:
>      >
>      >     How was VACUUM ANALYZE able to reclaim such a large amount of
>     space,
>      >     especially for TOAST data?
>      >
>      >     Under what conditions does PostgreSQL reclaim disk space without
>      >     requiring VACUUM FULL or CLUSTER?
>      >
>      >     Is this behavior expected in PostgreSQL 16, particularly for
>     heavily
>      >     updated or deleted TOASTed columns?
>      >
>      >     Any insights or documentation references would be greatly
>     appreciated.
>      >
>      >     PostgreSQL version: 16
>      >
>      >     Thanks in advance.
>      >     Pramod Gupta
>      >
> 
> 
>     -- 
>     Adrian Klaver
>     adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>
> 


-- 
Adrian Klaver
adrian.klaver@aklaver.com

On 1/15/26 09:48, pramod gupta wrote:
Again, you need to use Reply All to get post to mailing list
Ccinglist.


You did not answer 2) or 3).

Though the below is revealing:

> postgres@ANRPGTEST01:~$ ls -ltrh /var/lib/postgresql/.pg_ai.config
> -rw------- 1 postgres postgres 1.8K Jan 15 17:03 /var/lib/ 
> postgresql/.pg_ai.config
> postgres@ANRPGTEST01:~$ pwd
> /var/lib/postgresql
> postgres@ANRPGTEST01:~$ psql
> psql (16.11 (Ubuntu 16.11-1.pgdg24.04+1))
> Type "help" for help.
> 
> postgres=# \q

Per:
https://github.com/benodiwal/pg_ai_query/issues/38

"
benodiwal last month


Thanks for sharing, actually .pg_ai.config should be in your home 
directory and not root. Can u try to put it in home directory once and 
they try.

sudheermudunuri

same with me as well i added in /var/lib/postgresql/.pg_ai.config but 
still it doesn't load from the config file.

benodiwal


Hey @sudheermudunuri, it is designed this way in first release. Can u 
please try putting it in home dir.

"

-- 
Adrian Klaver
adrian.klaver@aklaver.com

On 1/15/26 10:22, pramod gupta wrote:
> postgres@ANRPGTEST01:~$ echo $HOME
> /var/lib/postgresql
> postgres@ANRPGTEST01:~$

I have to believe the extension author is referring to a user 
/home/some_user/ directory.

How are you getting to postgres@ANRPGTEST01?

What happens if you try something like?:

sudo -u postgres psql -d postgres -U postgres



> 
> On Thu, Jan 15, 2026 at 11:27 PM Adrian Klaver 
> <adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>> wrote:
> 
>     On 1/15/26 09:48, pramod gupta wrote:
>     Again, you need to use Reply All to get post to mailing list
>     Ccinglist.
> 
> 
>     You did not answer 2) or 3).
> 
>     Though the below is revealing:
> 
>      > postgres@ANRPGTEST01:~$ ls -ltrh /var/lib/postgresql/.pg_ai.config
>      > -rw------- 1 postgres postgres 1.8K Jan 15 17:03 /var/lib/
>      > postgresql/.pg_ai.config
>      > postgres@ANRPGTEST01:~$ pwd
>      > /var/lib/postgresql
>      > postgres@ANRPGTEST01:~$ psql
>      > psql (16.11 (Ubuntu 16.11-1.pgdg24.04+1))
>      > Type "help" for help.
>      >
>      > postgres=# \q
> 
>     Per:
>     https://github.com/benodiwal/pg_ai_query/issues/38 <https://
>     github.com/benodiwal/pg_ai_query/issues/38>
> 
>     "
>     benodiwal last month
> 
> 
>     Thanks for sharing, actually .pg_ai.config should be in your home
>     directory and not root. Can u try to put it in home directory once and
>     they try.
> 
>     sudheermudunuri
> 
>     same with me as well i added in /var/lib/postgresql/.pg_ai.config but
>     still it doesn't load from the config file.
> 
>     benodiwal
> 
> 
>     Hey @sudheermudunuri, it is designed this way in first release. Can u
>     please try putting it in home dir.
> 
>     "
> 
>     -- 
>     Adrian Klaver
>     adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>
> 


-- 
Adrian Klaver
adrian.klaver@aklaver.com

On 1/15/26 10:22, pramod gupta wrote:
> postgres@ANRPGTEST01:~$ echo $HOME
> /var/lib/postgresql
> postgres@ANRPGTEST01:~$
> 

Should have added to previous post:

Another thing to try is copy/move .pg_ai.config to your home directory 
and run psql from there.

-- 
Adrian Klaver
adrian.klaver@aklaver.com

> On Jan 15, 2026, at 11:52 AM, Adrian Klaver <adrian.klaver@aklaver.com> wrote:
>
> On 1/15/26 10:22, pramod gupta wrote:
>> postgres@ANRPGTEST01:~$ echo $HOME
>> /var/lib/postgresql
>> postgres@ANRPGTEST01:~$
>
> Should have added to previous post:
>
> Another thing to try is copy/move .pg_ai.config to your home directory and run psql from there.
>
> --
> Adrian Klaver
> adrian.klaver@aklaver.com
>
Is this a hijacked thread?
>

On 1/15/26 10:55, Rob Sargent wrote:
> 
> 
>> On Jan 15, 2026, at 11:52 AM, Adrian Klaver <adrian.klaver@aklaver.com> wrote:
>>
>> On 1/15/26 10:22, pramod gupta wrote:
>>> postgres@ANRPGTEST01:~$ echo $HOME
>>> /var/lib/postgresql
>>> postgres@ANRPGTEST01:~$
>>
>> Should have added to previous post:
>>
>> Another thing to try is copy/move .pg_ai.config to your home directory and run psql from there.
>>
>> --
>> Adrian Klaver
>> adrian.klaver@aklaver.com
>>
> Is this a hijacked thread?

Same author. I am not sure if what they are attempting with pg_ai_query 
is related to the original post or not.



-- 
Adrian Klaver
adrian.klaver@aklaver.com