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

On Mon, Dec 29, 2025 at 10:53 AM pramod gupta <mail2sony2010(at)gmail(dot)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
>

See the TRUNCATE option:
https://www.postgresql.org/docs/12/sql-vacuum.html

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