Re: Lock-free compaction. Why not?

Please don't top-post ...

On 7/21/24 16:42, Ahmed Yarub Hani Al Nuaimi wrote:
> That clearly explains the problem. But this got me thinking: what if we do
> both index and heap optimization at the same time?
> Meaning that the newly move heap tuple which is used to compact/defragment
> heap pages would be followed by moving the index (creating and then
> deleting) a new index tuple at the right place in the index data files (the
> one that had its dead tuples removed and internally defragmented, aka
> vacuumed). Deleting the old index could be done immediately after moving
> the heap tuple. I think that this can both solve the bloating problem and
> make sure that both the table and index heaps are in optimum shape, all of
> this being done lazily to make sure that these operations would only be
> done when the servers are not overwhelmed (or just using whatever logic our
> lazy vacuuming uses). What do you think?
>

I think this would run directly into the problems mentioned by Tom [1].
You say "immediately", but what does that mean? You need to explain how
would you ensure a scan (of arbitrary type) sees *exactly( one of the
heap/index tuples.

regards

--
Tomas Vondra
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