Re: Lock-free compaction. Why not?

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От Ahmed Yarub Hani Al Nuaimi
Тема Re: Lock-free compaction. Why not?
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Msg-id CAF239vqnUs9O71WVc5eFS-tkGV3AdTsDbrL5hAOXU05h_9q_dw@mail.gmail.com
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Ответ на Re: Lock-free compaction. Why not?  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: Lock-free compaction. Why not?
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Wow I was busy for a controle of days and now I’m again fully committed to this initiative. These ideas are extremely useful to my. I’ll first start by reading the old in-place implementation, but meanwhile I have the following questions:
1- I’m thinking of adding only one simple step to be auto-vacuum. This means that there will neither be excessive locking nor resource utilization. I guess my question is: does that simple step make the current lazy auto-vacuum much worse?
2- Can you point me to a resource explaining why this might lead to index bloating?

Em qui., 18 de jul. de 2024 às 15:21, Tom Lane <tgl@sss.pgh.pa.us> escreveu:
Robert Haas <robertmhaas@gmail.com> writes:
> On Thu, Jul 18, 2024 at 7:08 AM David Rowley <dgrowleyml@gmail.com> wrote:
>> I think the primary issue with the old way was index bloat wasn't
>> fixed. The release notes for 9.0 do claim the CLUSTER method "is
>> substantially faster in most cases", however, I imagine there are
>> plenty of cases where it wouldn't be. e.g, it's hard to imagine
>> rewriting the entire 1TB table and indexes is cheaper than moving 1
>> row out of place row.

> The other thing I remember besides index bloat is that it was
> crushingly slow.

Yeah.  The old way was great if there really were just a few tuples
needing to be moved ... but by the time you decide you need VACUUM
FULL rather than plain VACUUM, that's unlikely to be the case. 

                        regards, tom lane

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