Re: [HACKERS] Pluggable storage

int rs_ntuples; /* number of visible tuples on page */

OffsetNumber rs_vistuples[MaxHeapTuplesPerPage]; /* their offsets */

tsm_system_rows.c, nodeBitmapHeapscan.c, nodesamplescan.c

Used for retrieve the offsets mainly Bitmap and sample scans.

I think rest of the above parameters usage other than heap can be changed

once the Bitmap and Sample scans are modified to use the storage routines

while returning the tuple instead of their own implementations. I feel these

scans are the major users of the rest of the parameters. This approach may

need to some more API's to get rid of Bitmap and sample scan's own 

implementation.