| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Bruce Momjian <bruce(at)momjian(dot)us> |
| Cc: | 曾文旌 <wenjing(dot)zwj(at)alibaba-inc(dot)com>, Julien Rouhaud <rjuju123(at)gmail(dot)com>, Ibrar Ahmed <ibrar(dot)ahmad(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Peter Geoghegan <pg(at)bowt(dot)ie>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Amit Langote <amitlangote09(at)gmail(dot)com>, Hamid Akhtar <hamid(dot)akhtar(at)gmail(dot)com>, "heikki(dot)linnakangas" <heikki(dot)linnakangas(at)iki(dot)fi>, "Nasby, Jim" <nasbyj(at)amazon(dot)com> |
| Subject: | Re: Proposal: Global Index |
| Date: | 2021-01-11 18:34:32 |
| Message-ID: | 970988.1610390072@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Bruce Momjian <bruce(at)momjian(dot)us> writes:
> On Mon, Jan 11, 2021 at 07:40:18PM +0800, 曾文旌 wrote:
>> This is indeed a typical scenario for a partitioned table.
>> there are two basic operations
>> 1) Monthly DETACH old child table
>> 2) Monthly ATTACH new child table
>>
>> For 1) The DETACH old child table can be finished immediately, global index can be kept valid after DETACH is completed, and the cleanup of garbage data in global index can be deferred to VACUUM.
> Yes, we can keep the index rows for the deleted partition and clean them
> up later, but what is the advantage of partitioning then? Just heap
> deletion quickly? Is that enough of a value?
More to the point, you still have a massive index cleanup operation to do.
Deferred or not, that's going to take a lot of cycles, and it will leave
you with a bloated global index. I find it hard to believe that this
approach will seem like an improvement over doing partitioning the way
we do it now.
regards, tom lane
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