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help / color / mirror / Atom feedFrom: Sergey Sargsyan <[email protected]>
To: Mihail Nikalayeu <[email protected]>
Cc: Álvaro Herrera <[email protected]>
Cc: Andres Freund <[email protected]>
Cc: Michael Paquier <[email protected]>
Cc: PostgreSQL Hackers <[email protected]>
Cc: Andrey Borodin <[email protected]>
Cc: Melanie Plageman <[email protected]>
Cc: Matthias van de Meent <[email protected]>
Subject: Re: Revisiting {CREATE INDEX, REINDEX} CONCURRENTLY improvements
Date: Tue, 17 Jun 2025 18:55:54 +0300
Message-ID: <CAMAof69JSL8MYWG2qRScs3RQDpfcyZT_wFwW4SoAvftW+K_p1g@mail.gmail.com> (raw)
In-Reply-To: <CAMAof695VA+mbVRhWCTus=E0WnsMAQyqXxfOTohbcb7VUHSP4g@mail.gmail.com>
References: <CADzfLwW9QczZW-E=McxcjUv0e5VMDctQNETbgao0K-SimVhFPA@mail.gmail.com>
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<CAMAof695VA+mbVRhWCTus=E0WnsMAQyqXxfOTohbcb7VUHSP4g@mail.gmail.com>
Hello Mihail,
In patch v20-0006-Add-STIR-access-method-and-flags-related-to-auxi.patch,
within the "StirMarkAsSkipInserts" function, a critical section appears to
be left unclosed. This resulted in an assertion failure during ANALYZE of a
table containing a leftover STIR index.
Best regards,
Sergey
On Mon, Jun 16, 2025, 11:21 PM Sergey Sargsyan <
[email protected]> wrote:
> Thank you for the information. Tomorrow, I will also run a few tests to
> measure the time required to collect tids from the index; however, since I
> do not work with vanilla postgres, the results may vary.
>
> If the results indicate that this procedure is time-consuming, I maybe
> will develop an additional patch specifically for b-tree indexes, as they
> are the default and most commonly used type.
>
> Best regards,
> Sergey
>
>
> On Mon, Jun 16, 2025, 11:01 PM Mihail Nikalayeu <[email protected]>
> wrote:
>
>> Hello, Sergey!
>>
>> > I think it's to avoid duplicate errors when adding tuples from STIP to
>> the main index,
>> > but couldn't we just suppress that error during validation and skip the
>> new tuple insertion if it already exists?
>>
>> In some cases, it is not possible:
>> – Some index types (GiST, GIN, BRIN) do not provide an easy way to
>> detect such duplicates.
>> – When we are building a unique index, we cannot simply skip
>> duplicates, because doing so would also skip the rows that should
>> prevent the unique index from being created (unless we add extra logic
>> for B-tree indexes to compare TIDs as well).
>>
>> > The main index may get huge after building, and iterating over it in a
>> single thread and then sorting tids can be time consuming.
>> My tests indicate that the overhead is minor compared with the time
>> spent scanning the heap and building the index itself.
>>
>> > At least I guess one can skip it when STIP is empty.
>> Yes, that’s a good idea; I’ll add it later.
>>
>> > p.s. I noticed that `stip.c` has a lot of functions that don't follow
>> the Postgres coding style of return type on separate line.
>> Hmm... I’ll fix that as well.
>>
>> Best regards,
>> Mikhail.
>>
>
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Subject: Re: Revisiting {CREATE INDEX, REINDEX} CONCURRENTLY improvements
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