[HACKERS] pre-loading a user table.

[Ana Cerejo]

I am trying a pre-load a user table during InitPostgres.  I tried to mimic 
the relevant actions in ReverifyDatabase to carry this out.  I manage to 
load the first block of the table.  However, if a table is more than 1 
block, I end up getting warnings about relcache reference leaks. It looks 
like I need to increase the size of the relcache.  Can anyone comment on 
the approach and/or give me any advanced warnings about messing with the 
relcache?

Thanks!


Code follows:

/**
 * APC 4/1/04
 * 
 */static void
PreLoadUserTable(Oid relationId)
{
        Relation        pgdbrel;
        HeapScanDesc    pgtblscan;
        HeapTuple       tup;
        int i;
        fprintf(stdout, "APC: PreLoadTable for relation(%d).\n", 
                relationId);

        //      
        pgdbrel = heap_open(relationId, AccessShareLock);

        
        /* APC  numKeys seems to be 0 for user tables */
        /* pgdbscan = heap_beginscan(pgdbrel, SnapshotNow, 1, &key); */
        pgtblscan = heap_beginscan(pgdbrel, SnapshotNow, 0, NULL);

        fprintf(stdout, "APC: the number of blocks (%d)\n", 
                pgtblscan->rs_rd->rd_nblocks);
        
        /* XXX how to really load all the blocks, this approach is wrong */
        for (i=0; i<=i<pgtblscan->rs_rd->rd_nblocks; i++) {
        
                fprintf(stdout, "APC: the number of blocks (%d) for 
                round(%d)\n", pgtblscan->rs_rd->rd_nblocks, i);
                
                tup = heap_getnext(pgtblscan, ForwardScanDirection);
                
                
                if (!HeapTupleIsValid(tup))
                {
                        /* OOPS */
                        heap_close(pgdbrel, AccessShareLock);

                        /* ereport.... */
                        fprintf(stderr, "APC: FATAL ERROR unable to load 
                        the table during round(%d).\n", i);
                }
        }
        
        heap_endscan(pgtblscan);
        heap_close(pgdbrel, AccessShareLock);

        fprintf(stdout, "APC: PreLoadTable finished for relation(%d).\n", 
        relationId);

} 


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