Re: PATCH: pageinspect / add page_checksum and bt_page_items(bytea)

Hi,

On Wed, Mar 29, 2017 at 8:38 PM, Tomas Vondra
<tomas(dot)vondra(at)2ndquadrant(dot)com> wrote:
>
>
> On 03/24/2017 04:27 AM, Peter Eisentraut wrote:
>>
>> On 3/17/17 18:35, Tomas Vondra wrote:
>>>
>>> On 03/17/2017 05:23 PM, Peter Eisentraut wrote:
>>>>
>>>> I'm struggling to find a good way to share code between
>>>> bt_page_items(text, int4) and bt_page_items(bytea).
>>>>
>>>> If we do it via the SQL route, as I had suggested, it makes the
>>>> extension non-relocatable, and it will also create a bit of a mess
>>>> during upgrades.
>>>>
>>>> If doing it in C, it will be a bit tricky to pass the SRF context
>>>> around. There is no "DirectFunctionCall within SRF context", AFAICT.
>>>
>>>
>>> Not sure what it has to do with DirectFunctionCall? You want to call the
>>> bytea variant from the existing one? Wouldn't it be easier to simply
>>> define a static function with the shared parts, and pass around the
>>> fctx/fcinfo? Not quite pretty, but should work.
>>
>>
>> Perhaps what was added in
>>
>> <http://git.postgresql.org/pg/commitdiff/29bf5016835a2c2c23786f7cda347716c083d95f>
>> would actually work here.
>>
>
> I've tried to refactor the code using this, but the result was rather ugly
> because (a) it really is quite tricky to pass around the contexts and (b)
> the sanity checks are quite different for the two input types, so mixing
> those parts (essentially the SRF_IS_FIRSTCALL bits) does not make much sense
> IMHO.
>
> The attached patch is the best I came up with - it essentially shares just
> the tuple-forming part, which is exactly the same in both cases.
>
> It also adds the P_ISMETA(opaque) check to the original function, which
> seems like a useful defense against page written to a different place (which
> is essentially the issue I was originally investigating).
>

It seems like the latest patch(v4) shared by Tomas upthread is an
empty patch. If I am not wrong, please share the correct patch.
Thanks.

--
With Regards,
Ashutosh Sharma
EnterpriseDB:http://www.enterprisedb.com