Horton

Re: [proposal] de-TOAST'ing using a iterator

Binguo Bao <djydewang@gmail.com>

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From: Binguo Bao <djydewang@gmail.com>
To: Thomas Munro <thomas.munro@gmail.com>
Cc: Andrey Borodin <x4mmm@yandex-team.ru>, Atri Sharma <atri.jiit@gmail.com>, Stephen Frost <sfrost@snowman.net>, Владимир Лесков <vladimirlesk@yandex-team.ru>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2019-07-11T09:23:24Z
Lists: pgsql-hackers

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  1. Use single-byte Boyer-Moore-Horspool search even with multibyte encodings.

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I have set the local build configuration to be the same as on the CI. This
patch should be correct.

Best regards,
Binguo Bao

Binguo Bao <djydewang@gmail.com> 于2019年7月11日周四 上午12:39写道：

> This is the patch that fix warnings.
>
> Best Regards,
> Binguo Bao
>
> Binguo Bao <djydewang@gmail.com> 于2019年7月10日周三 下午10:18写道：
>
>> Hi Thomas,
>> I've fixed the warnings.
>>
>> Thomas Munro <thomas.munro@gmail.com> 于2019年7月5日周五 下午12:21写道：
>>
>>> On Thu, Jun 20, 2019 at 1:51 AM Binguo Bao <djydewang@gmail.com> wrote:
>>> > Hi hackers!
>>> > This proposal aims to provide the ability to de-TOAST a fully TOAST'd
>>> and compressed field using an iterator and then update the appropriate
>>> parts of the code to use the iterator where possible instead of
>>> de-TOAST'ing and de-compressing the entire value. Examples where this can
>>> be helpful include using position() from the beginning of the value, or
>>> doing a pattern or substring match.
>>> >
>>> > de-TOAST iterator overview:
>>> > 1. The caller requests the slice of the attribute value from the
>>> de-TOAST iterator.
>>> > 2. The de-TOAST iterator checks if there is a slice available in the
>>> output buffer, if there is, return the result directly,
>>> >     otherwise goto the step3.
>>> > 3. The de-TOAST iterator checks if there is the slice available in the
>>> input buffer, if there is, goto step44. Otherwise,
>>> >     call fetch_datum_iterator to fetch datums from disk to input
>>> buffer.
>>> > 4. If the data in the input buffer is compressed, extract some data
>>> from the input buffer to the output buffer until the caller's
>>> >     needs are met.
>>> >
>>> > I've implemented the prototype and apply it to the position() function
>>> to test performance.
>>>
>>> Hi Binguo,
>>>
>>> Interesting work, and nice performance improvements so far.  Just by
>>> the way, the patch currently generates warnings:
>>>
>>> https://travis-ci.org/postgresql-cfbot/postgresql/builds/554345719
>>>
>>> --
>>> Thomas Munro
>>> https://enterprisedb.com
>>>
>>