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postgresql/contrib/pgstattuple/pgstatindex.c

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/*
* contrib/pgstattuple/pgstatindex.c
*
*
* pgstatindex
*
* Copyright (c) 2006 Satoshi Nagayasu <nagayasus@nttdata.co.jp>
*
* 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/gin_private.h"
#include "access/hash.h"
#include "access/htup_details.h"
#include "access/nbtree.h"
#include "access/relation.h"
#include "access/table.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/rel.h"
#include "utils/varlena.h"
/*
* Because of backward-compatibility issue, we have decided to have
* two types of interfaces, with regclass-type input arg and text-type
* input arg, for each function.
*
* Those functions which have text-type input arg will be deprecated
* in the future release.
*/
PG_FUNCTION_INFO_V1(pgstatindex);
PG_FUNCTION_INFO_V1(pgstatindexbyid);
PG_FUNCTION_INFO_V1(pg_relpages);
PG_FUNCTION_INFO_V1(pg_relpagesbyid);
PG_FUNCTION_INFO_V1(pgstatginindex);
PG_FUNCTION_INFO_V1(pgstathashindex);
PG_FUNCTION_INFO_V1(pgstatindex_v1_5);
PG_FUNCTION_INFO_V1(pgstatindexbyid_v1_5);
PG_FUNCTION_INFO_V1(pg_relpages_v1_5);
PG_FUNCTION_INFO_V1(pg_relpagesbyid_v1_5);
PG_FUNCTION_INFO_V1(pgstatginindex_v1_5);
Datum pgstatginindex_internal(Oid relid, FunctionCallInfo fcinfo);
#define IS_INDEX(r) ((r)->rd_rel->relkind == RELKIND_INDEX)
#define IS_BTREE(r) ((r)->rd_rel->relam == BTREE_AM_OID)
#define IS_GIN(r) ((r)->rd_rel->relam == GIN_AM_OID)
#define IS_HASH(r) ((r)->rd_rel->relam == HASH_AM_OID)
/* ------------------------------------------------
* A structure for a whole btree index statistics
* used by pgstatindex().
* ------------------------------------------------
*/
typedef struct BTIndexStat
{
uint32 version;
uint32 level;
BlockNumber root_blkno;
uint64 internal_pages;
uint64 leaf_pages;
uint64 empty_pages;
uint64 deleted_pages;
uint64 max_avail;
uint64 free_space;
uint64 fragments;
} BTIndexStat;
/* ------------------------------------------------
* A structure for a whole GIN index statistics
* used by pgstatginindex().
* ------------------------------------------------
*/
typedef struct GinIndexStat
{
int32 version;
BlockNumber pending_pages;
int64 pending_tuples;
} GinIndexStat;
/* ------------------------------------------------
* A structure for a whole HASH index statistics
* used by pgstathashindex().
* ------------------------------------------------
*/
typedef struct HashIndexStat
{
int32 version;
int32 space_per_page;
BlockNumber bucket_pages;
BlockNumber overflow_pages;
BlockNumber bitmap_pages;
BlockNumber unused_pages;
int64 live_items;
int64 dead_items;
uint64 free_space;
} HashIndexStat;
static Datum pgstatindex_impl(Relation rel, FunctionCallInfo fcinfo);
static int64 pg_relpages_impl(Relation rel);
static void GetHashPageStats(Page page, HashIndexStat *stats);
/* ------------------------------------------------------
* pgstatindex()
*
* Usage: SELECT * FROM pgstatindex('t1_pkey');
*
* The superuser() check here must be kept as the library might be upgraded
* without the extension being upgraded, meaning that in pre-1.5 installations
* these functions could be called by any user.
* ------------------------------------------------------
*/
Datum
pgstatindex(PG_FUNCTION_ARGS)
{
text *relname = PG_GETARG_TEXT_PP(0);
Relation rel;
RangeVar *relrv;
if (!superuser())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("must be superuser to use pgstattuple functions")));
relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
rel = relation_openrv(relrv, AccessShareLock);
PG_RETURN_DATUM(pgstatindex_impl(rel, fcinfo));
}
/*
* As of pgstattuple version 1.5, we no longer need to check if the user
* is a superuser because we REVOKE EXECUTE on the function from PUBLIC.
* Users can then grant access to it based on their policies.
*
* Otherwise identical to pgstatindex (above).
*/
Datum
pgstatindex_v1_5(PG_FUNCTION_ARGS)
{
text *relname = PG_GETARG_TEXT_PP(0);
Relation rel;
RangeVar *relrv;
relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
rel = relation_openrv(relrv, AccessShareLock);
PG_RETURN_DATUM(pgstatindex_impl(rel, fcinfo));
}
/*
* The superuser() check here must be kept as the library might be upgraded
* without the extension being upgraded, meaning that in pre-1.5 installations
* these functions could be called by any user.
*/
Datum
pgstatindexbyid(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")));
rel = relation_open(relid, AccessShareLock);
PG_RETURN_DATUM(pgstatindex_impl(rel, fcinfo));
}
/* No need for superuser checks in v1.5, see above */
Datum
pgstatindexbyid_v1_5(PG_FUNCTION_ARGS)
{
Oid relid = PG_GETARG_OID(0);
Relation rel;
rel = relation_open(relid, AccessShareLock);
PG_RETURN_DATUM(pgstatindex_impl(rel, fcinfo));
}
static Datum
pgstatindex_impl(Relation rel, FunctionCallInfo fcinfo)
{
Datum result;
BlockNumber nblocks;
BlockNumber blkno;
BTIndexStat indexStat;
BufferAccessStrategy bstrategy = GetAccessStrategy(BAS_BULKREAD);
if (!IS_INDEX(rel) || !IS_BTREE(rel))
ereport(ERROR,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("relation \"%s\" is not a btree index",
RelationGetRelationName(rel))));
/*
* 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")));
/*
* A !indisready index could lead to ERRCODE_DATA_CORRUPTED later, so exit
* early. We're capable of assessing an indisready&&!indisvalid index,
* but the results could be confusing. For example, the index's size
* could be too low for a valid index of the table.
*/
if (!rel->rd_index->indisvalid)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("index \"%s\" is not valid",
RelationGetRelationName(rel))));
/*
* Read metapage
*/
{
Buffer buffer = ReadBufferExtended(rel, MAIN_FORKNUM, 0, RBM_NORMAL, bstrategy);
Page page = BufferGetPage(buffer);
BTMetaPageData *metad = BTPageGetMeta(page);
indexStat.version = metad->btm_version;
indexStat.level = metad->btm_level;
indexStat.root_blkno = metad->btm_root;
ReleaseBuffer(buffer);
}
/* -- init counters -- */
indexStat.internal_pages = 0;
indexStat.leaf_pages = 0;
indexStat.empty_pages = 0;
indexStat.deleted_pages = 0;
indexStat.max_avail = 0;
indexStat.free_space = 0;
indexStat.fragments = 0;
/*
* Scan all blocks except the metapage
*/
nblocks = RelationGetNumberOfBlocks(rel);
for (blkno = 1; blkno < nblocks; blkno++)
{
Buffer buffer;
Page page;
BTPageOpaque opaque;
CHECK_FOR_INTERRUPTS();
/* Read and lock buffer */
buffer = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL, bstrategy);
LockBuffer(buffer, BUFFER_LOCK_SHARE);
page = BufferGetPage(buffer);
opaque = BTPageGetOpaque(page);
/*
* Determine page type, and update totals.
*
* Note that we arbitrarily bucket deleted pages together without
* considering if they're leaf pages or internal pages.
*/
if (P_ISDELETED(opaque))
indexStat.deleted_pages++;
else if (P_IGNORE(opaque))
indexStat.empty_pages++; /* this is the "half dead" state */
else if (P_ISLEAF(opaque))
{
int max_avail;
max_avail = BLCKSZ - (BLCKSZ - ((PageHeader) page)->pd_special + SizeOfPageHeaderData);
indexStat.max_avail += max_avail;
indexStat.free_space += PageGetFreeSpace(page);
indexStat.leaf_pages++;
/*
* If the next leaf is on an earlier block, it means a
* fragmentation.
*/
if (opaque->btpo_next != P_NONE && opaque->btpo_next < blkno)
indexStat.fragments++;
}
else
indexStat.internal_pages++;
/* Unlock and release buffer */
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
ReleaseBuffer(buffer);
}
relation_close(rel, AccessShareLock);
/*----------------------------
* Build a result tuple
*----------------------------
*/
{
TupleDesc tupleDesc;
int j;
char *values[10];
HeapTuple tuple;
/* Build a tuple descriptor for our result type */
if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
j = 0;
values[j++] = psprintf("%d", indexStat.version);
values[j++] = psprintf("%d", indexStat.level);
values[j++] = psprintf(INT64_FORMAT,
(1 + /* include the metapage in index_size */
indexStat.leaf_pages +
indexStat.internal_pages +
indexStat.deleted_pages +
indexStat.empty_pages) * BLCKSZ);
values[j++] = psprintf("%u", indexStat.root_blkno);
values[j++] = psprintf(INT64_FORMAT, indexStat.internal_pages);
values[j++] = psprintf(INT64_FORMAT, indexStat.leaf_pages);
values[j++] = psprintf(INT64_FORMAT, indexStat.empty_pages);
values[j++] = psprintf(INT64_FORMAT, indexStat.deleted_pages);
if (indexStat.max_avail > 0)
values[j++] = psprintf("%.2f",
100.0 - (double) indexStat.free_space / (double) indexStat.max_avail * 100.0);
else
values[j++] = pstrdup("NaN");
if (indexStat.leaf_pages > 0)
values[j++] = psprintf("%.2f",
(double) indexStat.fragments / (double) indexStat.leaf_pages * 100.0);
else
values[j++] = pstrdup("NaN");
tuple = BuildTupleFromCStrings(TupleDescGetAttInMetadata(tupleDesc),
values);
result = HeapTupleGetDatum(tuple);
}
return result;
}
/* --------------------------------------------------------
* pg_relpages()
*
* Get the number of pages of the table/index.
*
* Usage: SELECT pg_relpages('t1');
* SELECT pg_relpages('t1_pkey');
*
* Must keep superuser() check, see above.
* --------------------------------------------------------
*/
Datum
pg_relpages(PG_FUNCTION_ARGS)
{
text *relname = PG_GETARG_TEXT_PP(0);
Relation rel;
RangeVar *relrv;
if (!superuser())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("must be superuser to use pgstattuple functions")));
relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
rel = relation_openrv(relrv, AccessShareLock);
PG_RETURN_INT64(pg_relpages_impl(rel));
}
/* No need for superuser checks in v1.5, see above */
Datum
pg_relpages_v1_5(PG_FUNCTION_ARGS)
{
text *relname = PG_GETARG_TEXT_PP(0);
Relation rel;
RangeVar *relrv;
relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
rel = relation_openrv(relrv, AccessShareLock);
PG_RETURN_INT64(pg_relpages_impl(rel));
}
/* Must keep superuser() check, see above. */
Datum
pg_relpagesbyid(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")));
rel = relation_open(relid, AccessShareLock);
PG_RETURN_INT64(pg_relpages_impl(rel));
}
/* No need for superuser checks in v1.5, see above */
Datum
pg_relpagesbyid_v1_5(PG_FUNCTION_ARGS)
{
Oid relid = PG_GETARG_OID(0);
Relation rel;
rel = relation_open(relid, AccessShareLock);
PG_RETURN_INT64(pg_relpages_impl(rel));
}
static int64
pg_relpages_impl(Relation rel)
{
int64 relpages;
if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind))
ereport(ERROR,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("cannot get page count of relation \"%s\"",
RelationGetRelationName(rel)),
errdetail_relkind_not_supported(rel->rd_rel->relkind)));
/* note: this will work OK on non-local temp tables */
relpages = RelationGetNumberOfBlocks(rel);
relation_close(rel, AccessShareLock);
return relpages;
}
/* ------------------------------------------------------
* pgstatginindex()
*
* Usage: SELECT * FROM pgstatginindex('ginindex');
*
* Must keep superuser() check, see above.
* ------------------------------------------------------
*/
Datum
pgstatginindex(PG_FUNCTION_ARGS)
{
Oid relid = PG_GETARG_OID(0);
if (!superuser())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("must be superuser to use pgstattuple functions")));
PG_RETURN_DATUM(pgstatginindex_internal(relid, fcinfo));
}
/* No need for superuser checks in v1.5, see above */
Datum
pgstatginindex_v1_5(PG_FUNCTION_ARGS)
{
Oid relid = PG_GETARG_OID(0);
PG_RETURN_DATUM(pgstatginindex_internal(relid, fcinfo));
}
Datum
pgstatginindex_internal(Oid relid, FunctionCallInfo fcinfo)
{
Relation rel;
Buffer buffer;
Page page;
GinMetaPageData *metadata;
GinIndexStat stats;
HeapTuple tuple;
TupleDesc tupleDesc;
Datum values[3];
bool nulls[3] = {false, false, false};
Datum result;
rel = relation_open(relid, AccessShareLock);
if (!IS_INDEX(rel) || !IS_GIN(rel))
ereport(ERROR,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("relation \"%s\" is not a GIN index",
RelationGetRelationName(rel))));
/*
* 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 indexes of other sessions")));
/* see pgstatindex_impl */
if (!rel->rd_index->indisvalid)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("index \"%s\" is not valid",
RelationGetRelationName(rel))));
/*
* Read metapage
*/
buffer = ReadBuffer(rel, GIN_METAPAGE_BLKNO);
LockBuffer(buffer, GIN_SHARE);
page = BufferGetPage(buffer);
metadata = GinPageGetMeta(page);
stats.version = metadata->ginVersion;
stats.pending_pages = metadata->nPendingPages;
stats.pending_tuples = metadata->nPendingHeapTuples;
UnlockReleaseBuffer(buffer);
relation_close(rel, AccessShareLock);
/*
* Build a tuple descriptor for our result type
*/
if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
values[0] = Int32GetDatum(stats.version);
values[1] = UInt32GetDatum(stats.pending_pages);
values[2] = Int64GetDatum(stats.pending_tuples);
/*
* Build and return the tuple
*/
tuple = heap_form_tuple(tupleDesc, values, nulls);
result = HeapTupleGetDatum(tuple);
return result;
}
/* ------------------------------------------------------
* pgstathashindex()
*
* Usage: SELECT * FROM pgstathashindex('hashindex');
* ------------------------------------------------------
*/
Datum
pgstathashindex(PG_FUNCTION_ARGS)
{
Oid relid = PG_GETARG_OID(0);
BlockNumber nblocks;
BlockNumber blkno;
Relation rel;
HashIndexStat stats;
BufferAccessStrategy bstrategy;
HeapTuple tuple;
TupleDesc tupleDesc;
Datum values[8];
bool nulls[8] = {0};
Buffer metabuf;
HashMetaPage metap;
float8 free_percent;
uint64 total_space;
rel = relation_open(relid, AccessShareLock);
if (!IS_INDEX(rel) || !IS_HASH(rel))
ereport(ERROR,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("relation \"%s\" is not a hash index",
RelationGetRelationName(rel))));
/*
* 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 indexes of other sessions")));
/* see pgstatindex_impl */
if (!rel->rd_index->indisvalid)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("index \"%s\" is not valid",
RelationGetRelationName(rel))));
/* Get the information we need from the metapage. */
memset(&stats, 0, sizeof(stats));
metabuf = _hash_getbuf(rel, HASH_METAPAGE, HASH_READ, LH_META_PAGE);
metap = HashPageGetMeta(BufferGetPage(metabuf));
stats.version = metap->hashm_version;
stats.space_per_page = metap->hashm_bsize;
_hash_relbuf(rel, metabuf);
/* Get the current relation length */
nblocks = RelationGetNumberOfBlocks(rel);
/* prepare access strategy for this index */
bstrategy = GetAccessStrategy(BAS_BULKREAD);
/* Start from blkno 1 as 0th block is metapage */
for (blkno = 1; blkno < nblocks; blkno++)
{
Buffer buf;
Page page;
CHECK_FOR_INTERRUPTS();
buf = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL,
bstrategy);
LockBuffer(buf, BUFFER_LOCK_SHARE);
page = (Page) BufferGetPage(buf);
if (PageIsNew(page))
stats.unused_pages++;
else if (PageGetSpecialSize(page) !=
MAXALIGN(sizeof(HashPageOpaqueData)))
ereport(ERROR,
(errcode(ERRCODE_INDEX_CORRUPTED),
errmsg("index \"%s\" contains corrupted page at block %u",
RelationGetRelationName(rel),
BufferGetBlockNumber(buf))));
else
{
HashPageOpaque opaque;
int pagetype;
opaque = HashPageGetOpaque(page);
pagetype = opaque->hasho_flag & LH_PAGE_TYPE;
if (pagetype == LH_BUCKET_PAGE)
{
stats.bucket_pages++;
GetHashPageStats(page, &stats);
}
else if (pagetype == LH_OVERFLOW_PAGE)
{
stats.overflow_pages++;
GetHashPageStats(page, &stats);
}
else if (pagetype == LH_BITMAP_PAGE)
stats.bitmap_pages++;
else if (pagetype == LH_UNUSED_PAGE)
stats.unused_pages++;
else
ereport(ERROR,
(errcode(ERRCODE_INDEX_CORRUPTED),
errmsg("unexpected page type 0x%04X in HASH index \"%s\" block %u",
opaque->hasho_flag, RelationGetRelationName(rel),
BufferGetBlockNumber(buf))));
}
UnlockReleaseBuffer(buf);
}
/* Done accessing the index */
index_close(rel, AccessShareLock);
/* Count unused pages as free space. */
stats.free_space += (uint64) stats.unused_pages * stats.space_per_page;
/*
* Total space available for tuples excludes the metapage and the bitmap
* pages.
*/
total_space = (uint64) (nblocks - (stats.bitmap_pages + 1)) *
stats.space_per_page;
if (total_space == 0)
free_percent = 0.0;
else
free_percent = 100.0 * stats.free_space / total_space;
/*
* Build a tuple descriptor for our result type
*/
if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
tupleDesc = BlessTupleDesc(tupleDesc);
/*
* Build and return the tuple
*/
values[0] = Int32GetDatum(stats.version);
values[1] = Int64GetDatum((int64) stats.bucket_pages);
values[2] = Int64GetDatum((int64) stats.overflow_pages);
values[3] = Int64GetDatum((int64) stats.bitmap_pages);
values[4] = Int64GetDatum((int64) stats.unused_pages);
values[5] = Int64GetDatum(stats.live_items);
values[6] = Int64GetDatum(stats.dead_items);
values[7] = Float8GetDatum(free_percent);
tuple = heap_form_tuple(tupleDesc, values, nulls);
PG_RETURN_DATUM(HeapTupleGetDatum(tuple));
}
/* -------------------------------------------------
* GetHashPageStats()
*
* Collect statistics of single hash page
* -------------------------------------------------
*/
static void
GetHashPageStats(Page page, HashIndexStat *stats)
{
OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
int off;
/* count live and dead tuples, and free space */
for (off = FirstOffsetNumber; off <= maxoff; off++)
{
ItemId id = PageGetItemId(page, off);
if (!ItemIdIsDead(id))
stats->live_items++;
else
stats->dead_items++;
}
stats->free_space += PageGetExactFreeSpace(page);
}
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