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/*
* contrib/pgstattuple/pgstattuple.c
*
* 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 "access/gist_private.h"
#include "access/hash.h"
#include "access/nbtree.h"
#include "access/relscan.h"
#include "catalog/namespace.h"
#include "catalog/pg_am.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "storage/bufmgr.h"
#include "storage/lmgr.h"
#include "utils/builtins.h"
#include "utils/tqual.h"
PG_MODULE_MAGIC;
PG_FUNCTION_INFO_V1(pgstattuple);
PG_FUNCTION_INFO_V1(pgstattuplebyid);
/*
* struct pgstattuple_type
*
* tuple_percent, dead_tuple_percent and free_percent are computable,
* so not defined here.
*/
typedef struct pgstattuple_type
{
uint64 table_len;
uint64 tuple_count;
uint64 tuple_len;
uint64 dead_tuple_count;
uint64 dead_tuple_len;
uint64 free_space; /* free/reusable space in bytes */
} pgstattuple_type;
typedef void (*pgstat_page) (pgstattuple_type *, Relation, BlockNumber,
BufferAccessStrategy);
static Datum build_pgstattuple_type(pgstattuple_type *stat,
FunctionCallInfo fcinfo);
static Datum pgstat_relation(Relation rel, FunctionCallInfo fcinfo);
static Datum pgstat_heap(Relation rel, FunctionCallInfo fcinfo);
static void pgstat_btree_page(pgstattuple_type *stat,
Relation rel, BlockNumber blkno,
BufferAccessStrategy bstrategy);
static void pgstat_hash_page(pgstattuple_type *stat,
Relation rel, BlockNumber blkno,
BufferAccessStrategy bstrategy);
static void pgstat_gist_page(pgstattuple_type *stat,
Relation rel, BlockNumber blkno,
BufferAccessStrategy bstrategy);
static Datum pgstat_index(Relation rel, BlockNumber start,
pgstat_page pagefn, FunctionCallInfo fcinfo);
static void pgstat_index_page(pgstattuple_type *stat, Page page,
OffsetNumber minoff, OffsetNumber maxoff);
/*
* build_pgstattuple_type -- build a pgstattuple_type tuple
*/
static Datum
build_pgstattuple_type(pgstattuple_type *stat, FunctionCallInfo fcinfo)
{
#define NCOLUMNS 9
#define NCHARS 32
HeapTuple tuple;
char *values[NCOLUMNS];
char values_buf[NCOLUMNS][NCHARS];
int i;
double tuple_percent;
double dead_tuple_percent;
double free_percent; /* free/reusable space in % */
TupleDesc tupdesc;
AttInMetadata *attinmeta;
/* Build a tuple descriptor for our result type */
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
/*
* Generate attribute metadata needed later to produce tuples from raw C
* strings
*/
attinmeta = TupleDescGetAttInMetadata(tupdesc);
if (stat->table_len == 0)
{
tuple_percent = 0.0;
dead_tuple_percent = 0.0;
free_percent = 0.0;
}
else
{
tuple_percent = 100.0 * stat->tuple_len / stat->table_len;
dead_tuple_percent = 100.0 * stat->dead_tuple_len / stat->table_len;
free_percent = 100.0 * stat->free_space / stat->table_len;
}
/*
* Prepare a values array for constructing the tuple. This should be an
* array of C strings which will be processed later by the appropriate
* "in" functions.
*/
for (i = 0; i < NCOLUMNS; i++)
values[i] = values_buf[i];
i = 0;
snprintf(values[i++], NCHARS, INT64_FORMAT, stat->table_len);
snprintf(values[i++], NCHARS, INT64_FORMAT, stat->tuple_count);
snprintf(values[i++], NCHARS, INT64_FORMAT, stat->tuple_len);
snprintf(values[i++], NCHARS, "%.2f", tuple_percent);
snprintf(values[i++], NCHARS, INT64_FORMAT, stat->dead_tuple_count);
snprintf(values[i++], NCHARS, INT64_FORMAT, stat->dead_tuple_len);
snprintf(values[i++], NCHARS, "%.2f", dead_tuple_percent);
snprintf(values[i++], NCHARS, INT64_FORMAT, stat->free_space);
snprintf(values[i++], NCHARS, "%.2f", free_percent);
/* build a tuple */
tuple = BuildTupleFromCStrings(attinmeta, values);
/* make the tuple into a datum */
return HeapTupleGetDatum(tuple);
}
/* ----------
* pgstattuple:
* returns live/dead tuples info
*
* C FUNCTION definition
* pgstattuple(text) returns pgstattuple_type
* ----------
*/
Datum
pgstattuple(PG_FUNCTION_ARGS)
{
text *relname = PG_GETARG_TEXT_P(0);
RangeVar *relrv;
Relation rel;
if (!superuser())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
(errmsg("must be superuser to use pgstattuple functions"))));
/* open relation */
relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
rel = relation_openrv(relrv, AccessShareLock);
PG_RETURN_DATUM(pgstat_relation(rel, fcinfo));
}
Datum
pgstattuplebyid(PG_FUNCTION_ARGS)
{
Oid relid = PG_GETARG_OID(0);
Relation rel;
if (!superuser())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
(errmsg("must be superuser to use pgstattuple functions"))));
/* open relation */
rel = relation_open(relid, AccessShareLock);
PG_RETURN_DATUM(pgstat_relation(rel, fcinfo));
}
/*
* pgstat_relation
*/
static Datum
pgstat_relation(Relation rel, FunctionCallInfo fcinfo)
{
const char *err;
/*
* Reject attempts to read non-local temporary relations; we would be
* likely to get wrong data since we have no visibility into the owning
* session's local buffers.
*/
if (RELATION_IS_OTHER_TEMP(rel))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot access temporary tables of other sessions")));
switch (rel->rd_rel->relkind)
{
case RELKIND_RELATION:
case RELKIND_MATVIEW:
case RELKIND_TOASTVALUE:
case RELKIND_SEQUENCE:
return pgstat_heap(rel, fcinfo);
case RELKIND_INDEX:
switch (rel->rd_rel->relam)
{
case BTREE_AM_OID:
return pgstat_index(rel, BTREE_METAPAGE + 1,
pgstat_btree_page, fcinfo);
case HASH_AM_OID:
return pgstat_index(rel, HASH_METAPAGE + 1,
pgstat_hash_page, fcinfo);
case GIST_AM_OID:
return pgstat_index(rel, GIST_ROOT_BLKNO + 1,
pgstat_gist_page, fcinfo);
case GIN_AM_OID:
err = "gin index";
break;
case SPGIST_AM_OID:
err = "spgist index";
break;
case BRIN_AM_OID:
err = "brin index";
break;
default:
err = "unknown index";
break;
}
break;
case RELKIND_VIEW:
err = "view";
break;
case RELKIND_COMPOSITE_TYPE:
err = "composite type";
break;
case RELKIND_FOREIGN_TABLE:
err = "foreign table";
break;
default:
err = "unknown";
break;
}
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("\"%s\" (%s) is not supported",
RelationGetRelationName(rel), err)));
return 0; /* should not happen */
}
/*
* pgstat_heap -- returns live/dead tuples info in a heap
*/
static Datum
pgstat_heap(Relation rel, FunctionCallInfo fcinfo)
{
HeapScanDesc scan;
HeapTuple tuple;
BlockNumber nblocks;
BlockNumber block = 0; /* next block to count free space in */
BlockNumber tupblock;
Buffer buffer;
pgstattuple_type stat = {0};
SnapshotData SnapshotDirty;
/* Disable syncscan because we assume we scan from block zero upwards */
scan = heap_beginscan_strat(rel, SnapshotAny, 0, NULL, true, false);
InitDirtySnapshot(SnapshotDirty);
nblocks = scan->rs_nblocks; /* # blocks to be scanned */
/* scan the relation */
while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
{
CHECK_FOR_INTERRUPTS();
/* must hold a buffer lock to call HeapTupleSatisfiesVisibility */
LockBuffer(scan->rs_cbuf, BUFFER_LOCK_SHARE);
if (HeapTupleSatisfiesVisibility(tuple, &SnapshotDirty, scan->rs_cbuf))
{
stat.tuple_len += tuple->t_len;
stat.tuple_count++;
}
else
{
stat.dead_tuple_len += tuple->t_len;
stat.dead_tuple_count++;
}
LockBuffer(scan->rs_cbuf, BUFFER_LOCK_UNLOCK);
/*
* 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)
{
CHECK_FOR_INTERRUPTS();
buffer = ReadBufferExtended(rel, MAIN_FORKNUM, block,
RBM_NORMAL, scan->rs_strategy);
LockBuffer(buffer, BUFFER_LOCK_SHARE);
stat.free_space += PageGetHeapFreeSpace((Page) BufferGetPage(buffer));
UnlockReleaseBuffer(buffer);
block++;
}
}
while (block < nblocks)
{
CHECK_FOR_INTERRUPTS();
buffer = ReadBufferExtended(rel, MAIN_FORKNUM, block,
RBM_NORMAL, scan->rs_strategy);
LockBuffer(buffer, BUFFER_LOCK_SHARE);
stat.free_space += PageGetHeapFreeSpace((Page) BufferGetPage(buffer));
UnlockReleaseBuffer(buffer);
block++;
}
heap_endscan(scan);
relation_close(rel, AccessShareLock);
stat.table_len = (uint64) nblocks *BLCKSZ;
return build_pgstattuple_type(&stat, fcinfo);
}
/*
* pgstat_btree_page -- check tuples in a btree page
*/
static void
pgstat_btree_page(pgstattuple_type *stat, Relation rel, BlockNumber blkno,
BufferAccessStrategy bstrategy)
{
Buffer buf;
Page page;
buf = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL, bstrategy);
LockBuffer(buf, BT_READ);
page = BufferGetPage(buf);
/* Page is valid, see what to do with it */
if (PageIsNew(page))
{
/* fully empty page */
stat->free_space += BLCKSZ;
}
else
{
BTPageOpaque opaque;
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
if (opaque->btpo_flags & (BTP_DELETED | BTP_HALF_DEAD))
{
/* recyclable page */
stat->free_space += BLCKSZ;
}
else if (P_ISLEAF(opaque))
{
pgstat_index_page(stat, page, P_FIRSTDATAKEY(opaque),
PageGetMaxOffsetNumber(page));
}
else
{
/* root or node */
}
}
_bt_relbuf(rel, buf);
}
/*
* pgstat_hash_page -- check tuples in a hash page
*/
static void
pgstat_hash_page(pgstattuple_type *stat, Relation rel, BlockNumber blkno,
BufferAccessStrategy bstrategy)
{
Buffer buf;
Page page;
_hash_getlock(rel, blkno, HASH_SHARE);
buf = _hash_getbuf_with_strategy(rel, blkno, HASH_READ, 0, bstrategy);
page = BufferGetPage(buf);
if (PageGetSpecialSize(page) == MAXALIGN(sizeof(HashPageOpaqueData)))
{
HashPageOpaque opaque;
opaque = (HashPageOpaque) PageGetSpecialPointer(page);
switch (opaque->hasho_flag)
{
case LH_UNUSED_PAGE:
stat->free_space += BLCKSZ;
break;
case LH_BUCKET_PAGE:
case LH_OVERFLOW_PAGE:
pgstat_index_page(stat, page, FirstOffsetNumber,
PageGetMaxOffsetNumber(page));
break;
case LH_BITMAP_PAGE:
case LH_META_PAGE:
default:
break;
}
}
else
{
/* maybe corrupted */
}
_hash_relbuf(rel, buf);
_hash_droplock(rel, blkno, HASH_SHARE);
}
/*
* pgstat_gist_page -- check tuples in a gist page
*/
static void
pgstat_gist_page(pgstattuple_type *stat, Relation rel, BlockNumber blkno,
BufferAccessStrategy bstrategy)
{
Buffer buf;
Page page;
buf = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL, bstrategy);
LockBuffer(buf, GIST_SHARE);
gistcheckpage(rel, buf);
page = BufferGetPage(buf);
if (GistPageIsLeaf(page))
{
pgstat_index_page(stat, page, FirstOffsetNumber,
PageGetMaxOffsetNumber(page));
}
else
{
/* root or node */
}
UnlockReleaseBuffer(buf);
}
/*
* pgstat_index -- returns live/dead tuples info in a generic index
*/
static Datum
pgstat_index(Relation rel, BlockNumber start, pgstat_page pagefn,
FunctionCallInfo fcinfo)
{
BlockNumber nblocks;
BlockNumber blkno;
BufferAccessStrategy bstrategy;
pgstattuple_type stat = {0};
/* prepare access strategy for this index */
bstrategy = GetAccessStrategy(BAS_BULKREAD);
blkno = start;
for (;;)
{
/* Get the current relation length */
LockRelationForExtension(rel, ExclusiveLock);
nblocks = RelationGetNumberOfBlocks(rel);
UnlockRelationForExtension(rel, ExclusiveLock);
/* Quit if we've scanned the whole relation */
if (blkno >= nblocks)
{
stat.table_len = (uint64) nblocks *BLCKSZ;
break;
}
for (; blkno < nblocks; blkno++)
{
CHECK_FOR_INTERRUPTS();
pagefn(&stat, rel, blkno, bstrategy);
}
}
relation_close(rel, AccessShareLock);
return build_pgstattuple_type(&stat, fcinfo);
}
/*
* pgstat_index_page -- for generic index page
*/
static void
pgstat_index_page(pgstattuple_type *stat, Page page,
OffsetNumber minoff, OffsetNumber maxoff)
{
OffsetNumber i;
stat->free_space += PageGetFreeSpace(page);
for (i = minoff; i <= maxoff; i = OffsetNumberNext(i))
{
ItemId itemid = PageGetItemId(page, i);
if (ItemIdIsDead(itemid))
{
stat->dead_tuple_count++;
stat->dead_tuple_len += ItemIdGetLength(itemid);
}
else
{
stat->tuple_count++;
stat->tuple_len += ItemIdGetLength(itemid);
}
}
}
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