Heikki Linnakangas napsal(a):
Pavan Deolasee wrote:
On Fri, Jul 4, 2008 at 1:01 PM, Zdenek Kotala <[EMAIL PROTECTED]> wrote:

Good catch. I lost in basic arithmetic. What I see now that original
definition count sizeof(ItemIdData) twice and on other side it does not take
care about MAXALING correctly. I think correct formula is:

#define HashMaxItemSize(page) \
       (PageGetPageSize(page) - \
         ( MAXALIGN(SizeOfPageHeaderData + sizeof(ItemIdData))+ \
           MAXALIGN(sizeof(HashPageOpaqueData)) \

What do you think?

Yes. I think that's the correct way.

Doesn't look right to me. There's no padding after the first line pointer, hence the first MAXALIGN shouldn't be there.

Are you sure? I expecting that tupleheader must be aligned to MAXALIGN. If it is not required than you are right.

Look on PageAddItem:

00226     alignedSize = MAXALIGN(size);
00228     upper = (int) phdr->pd_upper - (int) alignedSize;

By my opinion first place where tuple should be placed is:

MAXALIGN(SizeOfPageHeaderData + sizeof(ItemIdData))

BTW, looking at hashinsert.c where it's used, we're actually passing a pointer to the meta page to HashMaxItemSize(). So the PageGetPageSize() call on that is quite bogus, since it's not the meta page that the tuple is going to be inserted to. It's academical, because all pages are the same size anyway, but doesn't look right. I think I'd go with BLKCSZ instead.

Yeah, BLKCSZ looks good. Anyway, I plan to reorganize all *MaxItemSize staff to be compatible with in-place upgrade.

                thanks Zdenek

Zdenek Kotala              Sun Microsystems
Prague, Czech Republic     http://sun.com/postgresql

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