Tom Lane wrote:
>
>>
> Enough handwaving, what about specifics?
>
> 1. Forget moving tuples from one page to another. Doing that in a
> transaction-safe way is hugely expensive and complicated. Lazy VACUUM
> will only delete dead tuples and coalesce the free space thus made
> available within each page of a relation.
If we really need to move a tuple we can do it by a regular update that
SET-s nothing and just copies the tuple to another page inside a
separate
transaction.
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Hannu