Hello Zdenek,
On Thu, Oct 9, 2008 at 12:38 AM, Zdenek Kotala wrote:
Ryan Bradetich napsal(a):
On Wed, Oct 8, 2008 at 10:59 PM, Zdenek Kotala <Zdenek.Kotala@sun.com>
wrote:
I would like to see this patch (or some variant) go in if possible.
Since the inplace
upgrades a concern to you, is there anything I can do to help with the
inplace
upgrades to help offset the disruption this patch causes you?
Yaah, wait until 8.5 :-). However, currently there is no clear consensus
which upgrade method is best. I hope that It will clear after Prato
developers meeting. Until this meeting I cannot say more.
Heh, understood. :)

I believe the proposed CRC patch also affects the heap page layout (adds
the pd_checksum field to the PageHeaderData). [1] Just pointing out another
patch that could affect you as well. My offer to help still stands.
I overlooked 'd' test. Your idea seems to me reasonable. Maybe, you could
test 'd' alignment only for NOT NULL values.
Funny you should mention this. I had just started looking into this
optimization
to see if I could convince myself it would be safe. My initial
conclusion indicates
it would be safe, but I have not tested nor verified that yet. Having
an independent
proposal for this boosts my confidence even more. Thanks!
The problem there is add_item which it is used for indexes as well and they
has IndexTupleHeader structure. I'm not convenience about idea has two
different alignment for items on page.
Just to clarify, this patch only affects heap storage when (i.e. the
is_heap flag is
set). I have not had a chance to analyze or see if I can reduce
other storage types
yet.
I guess another problem is with MAX_TUPLE_CHUNK_SIZE which uses MAXALIGN for
computing. It seems to me that toast chunk could waste a space anyway.

And of course you should bump page layout version.
Thanks. I will do.
I also suggest create function/macro to compute hoff and replace code with
this function/macro.
Great. That is some of the feedback I was looking for. I did not
implement it yet,
because I wanted to see if the basic implementation was feasible first.

Thanks again for your feedback!

- Ryan


[1] http://archives.postgresql.org/pgsql-hackers/2008-10/msg00070.php

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