diff options
Diffstat (limited to 'src/include/access/htup.h')
| -rw-r--r-- | src/include/access/htup.h | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/src/include/access/htup.h b/src/include/access/htup.h index 7a77d438933..8bfdf26697e 100644 --- a/src/include/access/htup.h +++ b/src/include/access/htup.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/access/htup.h,v 1.99 2008/05/12 00:00:53 alvherre Exp $ + * $PostgreSQL: pgsql/src/include/access/htup.h,v 1.100 2008/07/13 20:45:47 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -362,12 +362,12 @@ do { \ * other stuff that has to be on a disk page. Since heap pages use no * "special space", there's no deduction for that. * - * NOTE: we do not need to count an ItemId for the tuple because - * sizeof(PageHeaderData) includes the first ItemId on the page. But beware - * of assuming that, say, you can fit 2 tuples of size MaxHeapTupleSize/2 - * on the same page. + * NOTE: we allow for the ItemId that must point to the tuple, ensuring that + * an otherwise-empty page can indeed hold a tuple of this size. Because + * ItemIds and tuples have different alignment requirements, don't assume that + * you can, say, fit 2 tuples of size MaxHeapTupleSize/2 on the same page. */ -#define MaxHeapTupleSize (BLCKSZ - MAXALIGN(sizeof(PageHeaderData))) +#define MaxHeapTupleSize (BLCKSZ - MAXALIGN(SizeOfPageHeaderData + sizeof(ItemIdData))) /* * MaxHeapTuplesPerPage is an upper bound on the number of tuples that can @@ -381,7 +381,7 @@ do { \ * require increases in the size of work arrays. */ #define MaxHeapTuplesPerPage \ - ((int) ((BLCKSZ - offsetof(PageHeaderData, pd_linp)) / \ + ((int) ((BLCKSZ - SizeOfPageHeaderData) / \ (MAXALIGN(offsetof(HeapTupleHeaderData, t_bits)) + sizeof(ItemIdData)))) /* |