Re: HOT Update || want to use a different page for updated tuple

On Fri, Apr 4, 2014 at 2:03 PM, Heikki Linnakangas
<hlinnakangas(at)vmware(dot)com>wrote:

> On 04/04/2014 02:53 PM, Rohit Goyal wrote:
>
>> Hi All,
>>
>> I was comparing postgresql performance and was just curious about
>> performance in case i want to store the updated index tuple version on a
>> different page.
>> I was looking into the code of heapam.c, but was not able to find loop
>> which i should remove so that postgresql use a different buffer for
>> updated
>> index tuple version.
>>
>
> Did you mean to:
>
> 1. Force the old and new tuple to always be stored on different pages?
>
> Hack heap_update so that it chooses a new page. I think you'll also need
> to hack RelationGetBufferForTuple to not return the same buffer.
>
> Can you explain a bit more from inside the code where i have to make the
changes :)? my focus is just to store the index tuple of an updated tuple
onto a different page or on a different buffer.

> 2. Disable the HOT optimization, so that HOT is not used even if the old
> and new tuple are stored on the same page?
>
> In heap_update, force satisfies_hot variable to false.
>
If I do change only this variable to false. then does it means, i have
disabled the hot update.?

>
> 3. Allow HOT to be used even though the old and new tuple are stored on
> different pages?
>
> This is not feasible..
>
> - Heikki
>

thanks in advance.!! :)

Regards,
Rohit Goyal

--
Regards,
Rohit Goyal