diff options
Diffstat (limited to 'src/include/access/htup.h')
| -rw-r--r-- | src/include/access/htup.h | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/src/include/access/htup.h b/src/include/access/htup.h index abc4dce9b9..6a78cd3a01 100644 --- a/src/include/access/htup.h +++ b/src/include/access/htup.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/access/htup.h,v 1.76 2005/08/20 00:39:59 tgl Exp $ + * $PostgreSQL: pgsql/src/include/access/htup.h,v 1.77 2005/09/02 19:02:20 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -324,6 +324,16 @@ do { \ (BLCKSZ - MAXALIGN(sizeof(PageHeaderData) + MaxSpecialSpace)) /* + * MaxHeapTuplesPerPage is an upper bound on the number of tuples that can + * fit on one heap page. (Note that indexes could have more, because they + * use a smaller tuple header.) We arrive at the divisor because each tuple + * must be maxaligned, and it must have an associated item pointer. + */ +#define MaxHeapTuplesPerPage \ + ((int) ((BLCKSZ - offsetof(PageHeaderData, pd_linp)) / \ + (MAXALIGN(offsetof(HeapTupleHeaderData, t_bits)) + sizeof(ItemIdData)))) + +/* * MaxAttrSize is a somewhat arbitrary upper limit on the declared size of * data fields of char(n) and similar types. It need not have anything * directly to do with the *actual* upper limit of varlena values, which |