Re: page macros cleanup
От | Zdenek Kotala |
---|---|
Тема | Re: page macros cleanup |
Дата | |
Msg-id | 486E03AF.2040402@sun.com обсуждение исходный текст |
Ответ на | Re: page macros cleanup ("Heikki Linnakangas" <heikki@enterprisedb.com>) |
Список | pgsql-patches |
Heikki Linnakangas napsal(a): > Pavan Deolasee wrote: >> On Fri, Jul 4, 2008 at 3:37 PM, Heikki Linnakangas >> <heikki@enterprisedb.com> wrote: >>> >>> I think this is the way it should be: >>> >>> #define HashMaxItemSize \ >>> (BLCKSZ - \ >>> SizeOfPageHeaderData - \ >>> MAXALIGN(sizeof(HashPageOpaqueData)) - \ >>> sizeof(ItemIdData)) >>> >> >> I am wondering if this would fail for corner case if HashMaxItemSize >> happened to be unaligned. For example, if (itemsz < HashMaxItemSize < >> MAXALIGN(itemsz), PageAddItem() would later fail with a not-so-obvious >> error. Should we just MAXALIGN_DOWN the HashMaxItemSize ? > > No, there's a itemsz = MAXALIGN(itemsz) call before the check against > HashMaxItemSize. It is tru, but id somebody will use HashMaxItemSize in different place in the future he could omit to use same approach. See tuptoaster.h how TOAST_MAX_CHUNK is defined or BTMaxItemSize in nbtree.h. Pavan's comments is correct. It should give same result as my implementation (because BLCKSZ is aligned), but it is better readable and consistent with other. Zdenek -- Zdenek Kotala Sun Microsystems Prague, Czech Republic http://sun.com/postgresql
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