> Tatsuo Ishii <t-ishii@sra.co.jp> writes:
> > I have written a small function that show how many tuples are dead
> > etc. in a specified table.
>
> Dead according to whose viewpoint? Under MVCC this seems to be
> in the eye of the beholder...
>
> > Shall I add this function into contrib directory?
>
> No real objection, but you should carefully document exactly what
> the results mean.
>
> BTW, I'd suggest accounting for free, reusable space separately from
> "overhead".
>
> regards, tom lane
Ok, here are the source code...
/** $Header: /home/t-ishii/repository/pgstattuple/pgstattuple.c,v 1.2 2001/08/30 06:21:48 t-ishii Exp $** Copyright (c)
2001 Tatsuo Ishii** Permission to use, copy, modify, and distribute this software and* its documentation for any
purpose,without fee, and without a* written agreement is hereby granted, provided that the above* copyright notice and
thisparagraph and the following two* paragraphs appear in all copies.*/
#include "postgres.h"
#include "fmgr.h"
#include "access/heapam.h"
#include "access/transam.h"
PG_FUNCTION_INFO_V1(pgstattuple);
extern Datum pgstattuple(PG_FUNCTION_ARGS);
/* ----------* pgstattuple:* returns the percentage of dead tuples** C FUNCTION definition* pgstattuple(NAME) returns
FLOAT8*----------*/
Datum
pgstattuple(PG_FUNCTION_ARGS)
{ Name p = PG_GETARG_NAME(0);
Relation rel; HeapScanDesc scan; HeapTuple tuple; BlockNumber nblocks; double table_len;
uint64 tuple_len = 0; uint64 dead_tuple_len = 0; uint32 tuple_count = 0; uint32 dead_tuple_count = 0;
double tuple_percent; double dead_tuple_percent;
rel = heap_openr(NameStr(*p), NoLock); nblocks = RelationGetNumberOfBlocks(rel); scan = heap_beginscan(rel,
false,SnapshotAny, 0, NULL);
while ((tuple = heap_getnext(scan,0))) {if (HeapTupleSatisfiesNow(tuple->t_data)){ tuple_len += tuple->t_len;
tuple_count++;}else{ dead_tuple_len += tuple->t_len; dead_tuple_count++;} } heap_endscan(scan);
heap_close(rel,NoLock);
table_len = (double)nblocks*BLCKSZ;
if (nblocks == 0) {tuple_percent = 0.0;dead_tuple_percent = 0.0; } else {tuple_percent =
(double)tuple_len*100.0/table_len;dead_tuple_percent= (double)dead_tuple_len*100.0/table_len; }
elog(NOTICE,"physical length: %.2fMB live tuples: %u (%.2fMB, %.2f%%) dead tuples: %u (%.2fMB, %.2f%%) overhead:
%.2f%%",
table_len/1024/1024,
tuple_count, (double)tuple_len/1024/1024, tuple_percent,
dead_tuple_count, (double)dead_tuple_len/1024/1024, dead_tuple_percent,
(nblocks == 0)?0.0: 100.0 - tuple_percent - dead_tuple_percent);
PG_RETURN_FLOAT8(dead_tuple_percent);
}
