On Tue, Jun 27, 2017 at 7:23 PM, Alexander Korotkov
<a.korotkov@postgrespro.ru> wrote:
> On Tue, Jun 27, 2017 at 4:08 PM, Amit Kapila <amit.kapila16@gmail.com>
> wrote:
>>
>> Similarly,
>> if the page format is changed you need to consider all page scan API's
>> like heapgettup_pagemode/heapgetpage.
>
>
> If page format is changed, then heapgettup_pagemode/heapgetpage should use
> appropriate API functions for manipulating page items. I'm very afraid of
> overriding whole heapgettup_pagemode/heapgetpage and monstrous functions
> like heap_update without understanding of clear use-case. It's definitely
> not needed for changing heap page format.
>
Yeah, we might not change them completely, there will always be some
common parts, but as of now, this API considers that we can return a
pointer to tuple on the page with just having a pin on the buffer.
This is based on the assumption that nobody can update the current
tuple, only a new tuple will be created on the update. For some use
cases like in-place updates, we might want to do that differently.
--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com