Re: Hardware/OS recommendations for large databases (

Luke Lonergan wrote:
> Mark,
>
> This is an excellent idea – unfortunately I’m in Maui right now
> (Mahalo!) and I’m not getting to testing with this.  My first try was
> with 8.0.3 and it’s an 8.1 function I presume.
>
> Not to be lazy – but any hint as to how to do the same thing for 8.0?
>

Yeah, it's 8.1 - I didn't think to check against 8.0. The attached
variant works with 8.0.4 (textToQualifiedNameList needs 2 args)

cheers

Mark

P.s. Maui eh, sounds real nice.
/*
 * fastcount.c
 *
 * Do a count that uses considerably less CPU time than an aggregate.
 *
 * (Variant for 8.0.x - textToQualifiedNameList needs 2 args)
 */

#include "postgres.h"

#include "funcapi.h"
#include "access/heapam.h"
#include "catalog/namespace.h"
#include "utils/builtins.h"


extern Datum fastcount(PG_FUNCTION_ARGS);


PG_FUNCTION_INFO_V1(fastcount);
Datum
fastcount(PG_FUNCTION_ARGS)
{
    text       *relname = PG_GETARG_TEXT_P(0);
    RangeVar   *relrv;
    Relation    rel;
    HeapScanDesc scan;
    HeapTuple    tuple;
    int64        result = 0;

    /* Use the name to get a suitable range variable and open the relation. */
    relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname, ""));
    rel = heap_openrv(relrv, AccessShareLock);

    /* Start a heap scan on the relation. */
    scan = heap_beginscan(rel, SnapshotNow, 0, NULL);
    while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
    {
        result++;
    }

    /* End the scan and close up the relation. */
    heap_endscan(scan);
    heap_close(rel, AccessShareLock);


    PG_RETURN_INT64(result);
}