Need some help on code

Hi,

I was trying to change to cluster command to do the its writes clustered
by a 100 tuples, thus hoping to improve performance. However, the code
I've written crashes. This has certainly to do with some internal states
of pgsql that aren't preserved in a HeapTuple.

Could somebody with knowledge have a brief glimpse on my code and perhaps
tell me how to do it properly?

Maarten

_____________________________________________________________________________
| TU Delft, The Netherlands, Faculty of Information Technology and Systems  |
|                   Department of Electrical Engineering                    |
|           Computer Architecture and Digital Technique section             |
|                          M.Boekhold@et.tudelft.nl                         |
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static void
rebuildheap(Oid OIDNewHeap, Oid OIDOldHeap, Oid OIDOldIndex)
{
    Relation    LocalNewHeap,
                LocalOldHeap,
                LocalOldIndex;
    IndexScanDesc ScanDesc;
    RetrieveIndexResult ScanResult;
    ItemPointer HeapTid;
    HeapTuple    LocalHeapTuple;
    Buffer        LocalBuffer[100];
    Oid            OIDNewHeapInsert;
    Dllist      *ScanResList;
    Dlelem      *ListEl;
    int         count, loop;

    /*
     * Open the relations I need. Scan through the OldHeap on the OldIndex
     * and insert each tuple into the NewHeap.
     */
    LocalNewHeap = (Relation) heap_open(OIDNewHeap);
    LocalOldHeap = (Relation) heap_open(OIDOldHeap);
    LocalOldIndex = (Relation) index_open(OIDOldIndex);
    ScanResList = DLNewList();

    ScanDesc = index_beginscan(LocalOldIndex, false, 0, (ScanKey) NULL);

    loop = 1;
    while (loop) {
        count = 0;
        while ((count < 100) &&
               ((ScanResult =
                index_getnext(ScanDesc,
                    ForwardScanDirection)) != NULL))
        {

            HeapTid = &ScanResult->heap_iptr;
            pfree(ScanResult);
            LocalHeapTuple = heap_fetch(LocalOldHeap, false,
                    HeapTid, &LocalBuffer[count]);
            ListEl = DLNewElem(LocalHeapTuple);
            DLAddTail(ScanResList, ListEl);
            count++;
        }

        if (count < 100) loop = 0;

        count = 0;
        while ((ListEl = DLRemHead(ScanResList)) != NULL) {
            LocalHeapTuple = (HeapTuple)ListEl->dle_val;
            DLFreeElem(ListEl);
            OIDNewHeapInsert =
                heap_insert(LocalNewHeap, LocalHeapTuple);
            ReleaseBuffer(LocalBuffer[count]);
            count++;
        }
    }

    index_endscan(ScanDesc);

    index_close(LocalOldIndex);
    heap_close(LocalOldHeap);
    heap_close(LocalNewHeap);
    DLFreeList(ScanResList);
}