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

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.

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.

3. Allow HOT to be used even though the old and new tuple are stored on
different pages?

This is not feasible..

- Heikki