Re: WIP: parallel GiST index builds - Mailing list pgsql-hackers

From Andrey M. Borodin
Subject Re: WIP: parallel GiST index builds
Date
Msg-id 9CBC7FE3-22D8-4F35-A631-AECD24418004@yandex-team.ru
Whole thread Raw
In response to Re: WIP: parallel GiST index builds  (Tomas Vondra <tomas.vondra@enterprisedb.com>)
Responses Re: WIP: parallel GiST index builds
List pgsql-hackers

> On 22 Jul 2024, at 14:53, Tomas Vondra <tomas.vondra@enterprisedb.com> wrote:
>
>
>
> On 7/22/24 13:08, Andrey M. Borodin wrote:
>>
>>
>>> On 22 Jul 2024, at 12:26, Tomas Vondra
>>> <tomas.vondra@enterprisedb.com> wrote:
>>>
>>> I don't understand how would that solve the problem, can you
>>> elaborate? Which of the values are you suggesting should be
>>> replaced with the shared counter? lastlsn?
>>
>> I think during build we should consider index unlogged and always use
>> GetFakeLSNForUnloggedRel() or something similar. Anyway we will
>> calllog_newpage_range(RelationGetNumberOfBlocks(index)) at the end.
>>
>
> But that doesn't update the page LSN, which GiST uses to detect
> concurrent splits, no?

During inserting tuples we need NSN on page. For NSN we can use just a counter, generated by gistGetFakeLSN() which in
turnwill call GetFakeLSNForUnloggedRel(). Or any other shared counter. 
After inserting tuples we call log_newpage_range() to actually WAL-log pages.
All NSNs used during build must be less than LSNs used to insert new tuples after index is built.


Best regards, Andrey Borodin.


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