Re: Setting pd_lower in GIN metapage

From: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
To: Michael Paquier <michael(dot)paquier(at)gmail(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Setting pd_lower in GIN metapage
Date: 2017-09-24 05:25:50
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On Wed, Sep 20, 2017 at 9:19 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> On Wed, Sep 20, 2017 at 4:25 AM, Michael Paquier
> <michael(dot)paquier(at)gmail(dot)com> wrote:
>> On Wed, Sep 20, 2017 at 12:47 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>> Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> writes:
>>>> On Tue, Sep 19, 2017 at 9:27 AM, Michael Paquier
>>>> <michael(dot)paquier(at)gmail(dot)com> wrote:
>>>>> I am not saying that no index AMs take advantage FPW compressibility
>>>>> for their meta pages. There are cases like this one, as well as one
>>>>> code path in BRIN where this is useful, and it is useful as well when
>>>>> logging FPWs of the init forks for unlogged relations.
>>>> Hmm, why is it useful for logging FPWs of the init forks for unlogged
>>>> relations? We don't use REGBUF_STANDARD in those cases.
>>> But if we started to do so, that would be a concrete benefit of this
>>> patch ...
>> In the proposed set of patches, all the empty() routines part of index
>> AMs which use log_newpage_buffer() (brin, gin, spgst) are doing the
>> right thing by updating log_newpage_buffer(). btree also should have
>> its call to log_newpage updated in btbuildempty(), and your patch is
>> missing that.
> We can add that for btree patch.

Added and updated the comments for both btree and hash index patches.

With Regards,
Amit Kapila.

Attachment Content-Type Size
change_metapage_usage_btree-v2.patch application/octet-stream 3.9 KB
change_metapage_usage_hash-v2.patch application/octet-stream 1.2 KB

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