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

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От Rohit Goyal
Тема Re: HOT Update || want to use a different page for updated tuple
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Msg-id CANqGtSsD-Rx_+PtLQ-6X3yzENa4i3DCbp=jmS3YWCVnFbuqQDQ@mail.gmail.com
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Ответ на Re: HOT Update || want to use a different page for updated tuple  (Heikki Linnakangas <hlinnakangas@vmware.com>)
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On Fri, Apr 4, 2014 at 2:03 PM, Heikki Linnakangas <hlinnakangas@vmware.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

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