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/*
* $Header: /cvsroot/pgsql/contrib/pgstattuple/pgstattuple.c,v 1.8 2002/08/29 17:14:31 tgl Exp $
*
* Copyright (c) 2001,2002 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 this paragraph and the following two
* paragraphs appear in all copies.
*
* IN NO EVENT SHALL THE AUTHOR BE LIABLE TO ANY PARTY FOR DIRECT,
* INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
* LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
* DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
* THE AUTHOR SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS
* IS" BASIS, AND THE AUTHOR HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE,
* SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*/
#include "postgres.h"
#include "fmgr.h"
#include "funcapi.h"
#include "access/heapam.h"
#include "access/transam.h"
#include "catalog/namespace.h"
#include "utils/builtins.h"
PG_FUNCTION_INFO_V1(pgstattuple);
extern Datum pgstattuple(PG_FUNCTION_ARGS);
/* ----------
* pgstattuple:
* returns live/dead tuples info
*
* C FUNCTION definition
* pgstattuple(text) returns pgstattuple_type
* see pgstattuple.sql for pgstattuple_type
* ----------
*/
#define DUMMY_TUPLE "pgstattuple_type"
#define NCOLUMNS 9
#define NCHARS 32
Datum
pgstattuple(PG_FUNCTION_ARGS)
{
text *relname = PG_GETARG_TEXT_P(0);
RangeVar *relrv;
Relation rel;
HeapScanDesc scan;
HeapTuple tuple;
BlockNumber nblocks;
BlockNumber block = 0; /* next block to count free space in */
BlockNumber tupblock;
Buffer buffer;
uint64 table_len;
uint64 tuple_len = 0;
uint64 dead_tuple_len = 0;
uint64 tuple_count = 0;
uint64 dead_tuple_count = 0;
double tuple_percent;
double dead_tuple_percent;
uint64 free_space = 0; /* free/reusable space in bytes */
double free_percent; /* free/reusable space in % */
TupleDesc tupdesc;
TupleTableSlot *slot;
AttInMetadata *attinmeta;
char **values;
int i;
Datum result;
/*
* Build a tuple description for a pgstattupe_type tuple
*/
tupdesc = RelationNameGetTupleDesc(DUMMY_TUPLE);
/* allocate a slot for a tuple with this tupdesc */
slot = TupleDescGetSlot(tupdesc);
/*
* Generate attribute metadata needed later to produce tuples from raw
* C strings
*/
attinmeta = TupleDescGetAttInMetadata(tupdesc);
/* open relation */
relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname,
"pgstattuple"));
rel = heap_openrv(relrv, AccessShareLock);
nblocks = RelationGetNumberOfBlocks(rel);
scan = heap_beginscan(rel, SnapshotAny, 0, NULL);
/* scan the relation */
while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
{
if (HeapTupleSatisfiesNow(tuple->t_data))
{
tuple_len += tuple->t_len;
tuple_count++;
}
else
{
dead_tuple_len += tuple->t_len;
dead_tuple_count++;
}
/*
* To avoid physically reading the table twice, try to do the
* free-space scan in parallel with the heap scan. However,
* heap_getnext may find no tuples on a given page, so we cannot
* simply examine the pages returned by the heap scan.
*/
tupblock = BlockIdGetBlockNumber(&tuple->t_self.ip_blkid);
while (block <= tupblock)
{
buffer = ReadBuffer(rel, block);
free_space += PageGetFreeSpace((Page) BufferGetPage(buffer));
ReleaseBuffer(buffer);
block++;
}
}
heap_endscan(scan);
while (block < nblocks)
{
buffer = ReadBuffer(rel, block);
free_space += PageGetFreeSpace((Page) BufferGetPage(buffer));
ReleaseBuffer(buffer);
block++;
}
heap_close(rel, AccessShareLock);
table_len = (uint64)nblocks *BLCKSZ;
if (nblocks == 0)
{
tuple_percent = 0.0;
dead_tuple_percent = 0.0;
free_percent = 0.0;
}
else
{
tuple_percent = (double) tuple_len *100.0 / table_len;
dead_tuple_percent = (double) dead_tuple_len *100.0 / table_len;
free_percent = (double) free_space *100.0 / table_len;
}
/*
* Prepare a values array for storage in our slot.
* This should be an array of C strings which will
* be processed later by the appropriate "in" functions.
*/
values = (char **) palloc(NCOLUMNS * sizeof(char *));
for (i=0;i<NCOLUMNS;i++)
{
values[i] = (char *) palloc(NCHARS * sizeof(char));
}
i = 0;
snprintf(values[i++], NCHARS, "%lld", table_len);
snprintf(values[i++], NCHARS, "%lld", tuple_count);
snprintf(values[i++], NCHARS, "%lld", tuple_len);
snprintf(values[i++], NCHARS, "%.2f", tuple_percent);
snprintf(values[i++], NCHARS, "%lld", dead_tuple_count);
snprintf(values[i++], NCHARS, "%lld", dead_tuple_len);
snprintf(values[i++], NCHARS, "%.2f", dead_tuple_percent);
snprintf(values[i++], NCHARS, "%lld", free_space);
snprintf(values[i++], NCHARS, "%.2f", free_percent);
/* build a tuple */
tuple = BuildTupleFromCStrings(attinmeta, values);
/* make the tuple into a datum */
result = TupleGetDatum(slot, tuple);
/* Clean up */
for (i=0;i<NCOLUMNS;i++)
{
pfree(values[i]);
}
pfree(values);
PG_RETURN_DATUM(result);
}
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