From: | Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp> |
---|---|
To: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Setting pd_lower in GIN metapage |
Date: | 2017-06-21 00:42:47 |
Message-ID: | a114ed01-fed6-2f5a-4be5-ed126b998d8e@lab.ntt.co.jp |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
On 2017/06/20 20:37, Amit Kapila wrote:
> On Tue, Jun 20, 2017 at 1:50 PM, Amit Langote
> <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp> wrote:
>> On 2017/06/19 23:31, Tom Lane wrote:
>>> I'd suggest a rule like "if pd_lower is smaller than SizeOfPageHeaderData
>>> then don't trust it, but assume all of the page is valid data".
>>
>> Actually, such a check is already in place in the tool, whose condition
>> looks like:
>>
>> if (PageGetPageSize(header) == BLCKSZ &&
>> PageGetPageLayoutVersion(header) == PG_PAGE_LAYOUT_VERSION &&
>> (header->pd_flags & ~PD_VALID_FLAG_BITS) == 0 &&
>> header->pd_lower >= SizeOfPageHeaderData &&
>> header->pd_lower <= header->pd_upper &&
>> header->pd_upper <= header->pd_special &&
>> header->pd_special <= BLCKSZ &&
>> header->pd_special == MAXALIGN(header->pd_special) && ...
>>
>> which even GIN metapage passes, making it an eligible data page and hence
>> for omitting the hole between pd_lower and pd_upper.
>>
>
> Won't checking for GIN_META in header->pd_flags gives you what you want?
GIN_META flag is not written into pd_flags but GinPageOpaqueData.flags,
which still requires including GIN's private header.
Thanks,
Amit
From | Date | Subject | |
---|---|---|---|
Next Message | Amit Langote | 2017-06-21 01:15:28 | Re: Beta 10 parser error for CREATE STATISTICS IF NOT EXISTS |
Previous Message | Bruno Wolff III | 2017-06-21 00:42:37 | Beta 10 parser error for CREATE STATISTICS IF NOT EXISTS |