Re: page macros cleanup
"Heikki Linnakangas" <[email protected]>
| Newsgroups | gmane.comp.db.postgresql.devel.patches |
|---|---|
| Organization | EnterpriseDB |
| Message-ID | <[email protected]> |
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. 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. I think this is the way it should be: #define HashMaxItemSize \ (BLCKSZ - \ SizeOfPageHeaderData - \ MAXALIGN(sizeof(HashPageOpaqueData)) - \ sizeof(ItemIdData)) -- 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