Re: page macros cleanup
"Heikki Linnakangas" <[email protected]>
| Newsgroups | gmane.comp.db.postgresql.devel.patches |
|---|---|
| Organization | EnterpriseDB |
| Message-ID | <[email protected]> |
Zdenek Kotala wrote: > By my opinion first place where tuple should be placed is: > > MAXALIGN(SizeOfPageHeaderData + sizeof(ItemIdData)) Yeah, but we don't enforce that directly. We enforce it by MAXALIGNing size in PageAddItem, and with the rule that special-size is MAXALIGNed. To put it another way, it's possible that there's an unaligned amount of free space on a page, as returned by PageGetExactFreeSpace. But since item size is always MAXALIGNed, it's impossible to use it all. Come to think of it, why do we require MAXALIGN alignment of tuples? I must be missing something, but AFAICS the widest fields in HeapTupleHeaderData are 4-bytes wide, so it should be possible to get away with 4-byte alignment. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com -- Sent via pgsql-patches mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-patches