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postgresql/contrib/pgstattuple/pgstatindex.c

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/*
* 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 "fmgr.h"
#include "funcapi.h"
#include "access/heapam.h"
#include "access/itup.h"
#include "access/nbtree.h"
#include "access/transam.h"
#include "catalog/namespace.h"
#include "catalog/pg_type.h"
#include "miscadmin.h"
#include "utils/builtins.h"
#include "utils/inval.h"
PG_FUNCTION_INFO_V1(pgstatindex);
PG_FUNCTION_INFO_V1(bt_metap);
PG_FUNCTION_INFO_V1(bt_page_items);
PG_FUNCTION_INFO_V1(bt_page_stats);
PG_FUNCTION_INFO_V1(pg_relpages);
extern Datum pgstatindex(PG_FUNCTION_ARGS);
extern Datum bt_metap(PG_FUNCTION_ARGS);
extern Datum bt_page_items(PG_FUNCTION_ARGS);
extern Datum bt_page_stats(PG_FUNCTION_ARGS);
extern Datum pg_relpages(PG_FUNCTION_ARGS);
#define PGSTATINDEX_TYPE "public.pgstatindex_type"
#define PGSTATINDEX_NCOLUMNS 10
#define BTMETAP_TYPE "public.bt_metap_type"
#define BTMETAP_NCOLUMNS 6
#define BTPAGEITEMS_TYPE "public.bt_page_items_type"
#define BTPAGEITEMS_NCOLUMNS 6
#define BTPAGESTATS_TYPE "public.bt_page_stats_type"
#define BTPAGESTATS_NCOLUMNS 11
#define IS_INDEX(r) ((r)->rd_rel->relkind == 'i')
#define IS_BTREE(r) ((r)->rd_rel->relam == BTREE_AM_OID)
#define CHECK_PAGE_OFFSET_RANGE(pg, offnum) { \
if ( !(FirstOffsetNumber <= (offnum) && \
(offnum) <= PageGetMaxOffsetNumber(pg)) ) \
elog(ERROR, "page offset number out of range"); }
/* note: BlockNumber is unsigned, hence can't be negative */
#define CHECK_RELATION_BLOCK_RANGE(rel, blkno) { \
if ( RelationGetNumberOfBlocks(rel) <= (BlockNumber) (blkno) ) \
elog(ERROR, "block number out of range"); }
/* ------------------------------------------------
* structure for single btree page statistics
* ------------------------------------------------
*/
typedef struct BTPageStat
{
uint32 blkno;
uint32 live_items;
uint32 dead_items;
uint32 page_size;
uint32 max_avail;
uint32 free_size;
uint32 avg_item_size;
uint32 fragments;
char type;
/* opaque data */
BlockNumber btpo_prev;
BlockNumber btpo_next;
union
{
uint32 level;
TransactionId xact;
} btpo;
uint16 btpo_flags;
BTCycleId btpo_cycleid;
} BTPageStat;
/* ------------------------------------------------
* A structure for a whole btree index statistics
* used by pgstatindex().
* ------------------------------------------------
*/
typedef struct BTIndexStat
{
uint32 magic;
uint32 version;
BlockNumber root_blkno;
uint32 level;
BlockNumber fastroot;
uint32 fastlevel;
uint32 live_items;
uint32 dead_items;
uint32 root_pages;
uint32 internal_pages;
uint32 leaf_pages;
uint32 empty_pages;
uint32 deleted_pages;
uint32 page_size;
uint32 avg_item_size;
uint32 max_avail;
uint32 free_space;
uint32 fragments;
} BTIndexStat;
/* -------------------------------------------------
* GetBTPageStatistics()
*
* Collect statistics of single b-tree leaf page
* -------------------------------------------------
*/
static void
GetBTPageStatistics(BlockNumber blkno, Buffer buffer, BTPageStat * stat)
{
Page page = BufferGetPage(buffer);
PageHeader phdr = (PageHeader) page;
OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
BTPageOpaque opaque = (BTPageOpaque) PageGetSpecialPointer(page);
int item_size = 0;
int off;
stat->blkno = blkno;
stat->max_avail = BLCKSZ - (BLCKSZ - phdr->pd_special + SizeOfPageHeaderData);
stat->dead_items = stat->live_items = 0;
stat->fragments = 0;
stat->page_size = PageGetPageSize(page);
/* page type (flags) */
if (P_ISDELETED(opaque))
{
stat->type = 'd';
stat->btpo.xact = opaque->btpo.xact;
return;
}
else if (P_IGNORE(opaque))
stat->type = 'e';
else if (P_ISLEAF(opaque))
stat->type = 'l';
else if (P_ISROOT(opaque))
stat->type = 'r';
else
stat->type = 'i';
/* btpage opaque data */
stat->btpo_prev = opaque->btpo_prev;
stat->btpo_next = opaque->btpo_next;
stat->btpo.level = opaque->btpo.level;
stat->btpo_flags = opaque->btpo_flags;
stat->btpo_cycleid = opaque->btpo_cycleid;
/*----------------------------------------------
* If a next leaf is on the previous block,
* it means a fragmentation.
*----------------------------------------------
*/
if (stat->type == 'l')
{
if (opaque->btpo_next != P_NONE && opaque->btpo_next < blkno)
stat->fragments++;
}
/* count live and dead tuples, and free space */
for (off = FirstOffsetNumber; off <= maxoff; off++)
{
IndexTuple itup;
ItemId id = PageGetItemId(page, off);
itup = (IndexTuple) PageGetItem(page, id);
item_size += IndexTupleSize(itup);
if (!ItemIdDeleted(id))
stat->live_items++;
else
stat->dead_items++;
}
stat->free_size = PageGetFreeSpace(page);
if ((stat->live_items + stat->dead_items) > 0)
stat->avg_item_size = item_size / (stat->live_items + stat->dead_items);
else
stat->avg_item_size = 0;
}
/* ------------------------------------------------------
* pgstatindex()
*
* Usage: SELECT * FROM pgstatindex('t1_pkey');
* ------------------------------------------------------
*/
Datum
pgstatindex(PG_FUNCTION_ARGS)
{
text *relname = PG_GETARG_TEXT_P(0);
Relation rel;
RangeVar *relrv;
Datum result;
uint32 nblocks;
uint32 blkno;
BTIndexStat indexStat;
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);
if (!IS_INDEX(rel) || !IS_BTREE(rel))
elog(ERROR, "pgstatindex() can be used only on b-tree index.");
/*
* 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 (isOtherTempNamespace(RelationGetNamespace(rel)))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot access temporary tables of other sessions")));
/*-------------------
* Read a metapage
*-------------------
*/
{
Buffer buffer = ReadBuffer(rel, 0);
Page page = BufferGetPage(buffer);
BTMetaPageData *metad = BTPageGetMeta(page);
indexStat.magic = metad->btm_magic;
indexStat.version = metad->btm_version;
indexStat.root_blkno = metad->btm_root;
indexStat.level = metad->btm_level;
indexStat.fastroot = metad->btm_fastroot;
indexStat.fastlevel = metad->btm_fastlevel;
ReleaseBuffer(buffer);
}
nblocks = RelationGetNumberOfBlocks(rel);
/* -- init stat -- */
indexStat.fragments = 0;
indexStat.root_pages = 0;
indexStat.leaf_pages = 0;
indexStat.internal_pages = 0;
indexStat.empty_pages = 0;
indexStat.deleted_pages = 0;
indexStat.max_avail = 0;
indexStat.free_space = 0;
/*-----------------------
* Scan all blocks
*-----------------------
*/
for (blkno = 1; blkno < nblocks; blkno++)
{
Buffer buffer = ReadBuffer(rel, blkno);
BTPageStat stat;
CHECK_FOR_INTERRUPTS();
/* scan one page */
stat.blkno = blkno;
GetBTPageStatistics(blkno, buffer, &stat);
/*---------------------
* page status (type)
*---------------------
*/
switch (stat.type)
{
case 'd':
indexStat.deleted_pages++;
break;
case 'l':
indexStat.leaf_pages++;
break;
case 'i':
indexStat.internal_pages++;
break;
case 'e':
indexStat.empty_pages++;
break;
case 'r':
indexStat.root_pages++;
break;
default:
elog(ERROR, "unknown page status.");
}
/* -- leaf fragmentation -- */
indexStat.fragments += stat.fragments;
if (stat.type == 'l')
{
indexStat.max_avail += stat.max_avail;
indexStat.free_space += stat.free_size;
}
ReleaseBuffer(buffer);
}
relation_close(rel, AccessShareLock);
/*----------------------------
* Build a result tuple
*----------------------------
*/
{
TupleDesc tupleDesc;
int j;
char *values[PGSTATINDEX_NCOLUMNS];
HeapTuple tuple;
tupleDesc = RelationNameGetTupleDesc(PGSTATINDEX_TYPE);
j = 0;
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", indexStat.version);
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", indexStat.level);
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", (indexStat.root_pages +
indexStat.leaf_pages +
indexStat.internal_pages +
indexStat.deleted_pages +
indexStat.empty_pages) * BLCKSZ);
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", indexStat.root_blkno);
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", indexStat.internal_pages);
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", indexStat.leaf_pages);
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", indexStat.empty_pages);
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", indexStat.deleted_pages);
values[j] = palloc(32);
if (indexStat.max_avail > 0)
snprintf(values[j++], 32, "%.2f",
100.0 - (double) indexStat.free_space / (double) indexStat.max_avail * 100.0);
else
snprintf(values[j++], 32, "NaN");
values[j] = palloc(32);
if (indexStat.leaf_pages > 0)
snprintf(values[j++], 32, "%.2f",
(double) indexStat.fragments / (double) indexStat.leaf_pages * 100.0);
else
snprintf(values[j++], 32, "NaN");
tuple = BuildTupleFromCStrings(TupleDescGetAttInMetadata(tupleDesc),
values);
result = TupleGetDatum(TupleDescGetSlot(tupleDesc), tuple);
}
PG_RETURN_DATUM(result);
}
/* -----------------------------------------------
* bt_page()
*
* Usage: SELECT * FROM bt_page('t1_pkey', 0);
* -----------------------------------------------
*/
Datum
bt_page_stats(PG_FUNCTION_ARGS)
{
text *relname = PG_GETARG_TEXT_P(0);
uint32 blkno = PG_GETARG_UINT32(1);
Buffer buffer;
Relation rel;
RangeVar *relrv;
Datum result;
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);
if (!IS_INDEX(rel) || !IS_BTREE(rel))
elog(ERROR, "bt_page_stats() can be used only on b-tree index.");
/*
* 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 (isOtherTempNamespace(RelationGetNamespace(rel)))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot access temporary tables of other sessions")));
if (blkno == 0)
elog(ERROR, "Block 0 is a meta page.");
CHECK_RELATION_BLOCK_RANGE(rel, blkno);
buffer = ReadBuffer(rel, blkno);
{
HeapTuple tuple;
TupleDesc tupleDesc;
int j;
char *values[BTPAGESTATS_NCOLUMNS];
BTPageStat stat;
GetBTPageStatistics(blkno, buffer, &stat);
tupleDesc = RelationNameGetTupleDesc(BTPAGESTATS_TYPE);
j = 0;
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", stat.blkno);
values[j] = palloc(32);
snprintf(values[j++], 32, "%c", stat.type);
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", stat.live_items);
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", stat.dead_items);
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", stat.avg_item_size);
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", stat.page_size);
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", stat.free_size);
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", stat.btpo_prev);
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", stat.btpo_next);
values[j] = palloc(32);
if (stat.type == 'd')
snprintf(values[j++], 32, "%d", stat.btpo.xact);
else
snprintf(values[j++], 32, "%d", stat.btpo.level);
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", stat.btpo_flags);
tuple = BuildTupleFromCStrings(TupleDescGetAttInMetadata(tupleDesc),
values);
result = TupleGetDatum(TupleDescGetSlot(tupleDesc), tuple);
}
ReleaseBuffer(buffer);
relation_close(rel, AccessShareLock);
PG_RETURN_DATUM(result);
}
/*-------------------------------------------------------
* bt_page_items()
*
* Get IndexTupleData set in a leaf page
*
* Usage: SELECT * FROM bt_page_items('t1_pkey', 0);
*-------------------------------------------------------
*/
/* ---------------------------------------------------
* data structure for SRF to hold a scan information
* ---------------------------------------------------
*/
struct user_args
{
TupleDesc tupd;
Relation rel;
Buffer buffer;
Page page;
uint16 offset;
};
Datum
bt_page_items(PG_FUNCTION_ARGS)
{
text *relname = PG_GETARG_TEXT_P(0);
uint32 blkno = PG_GETARG_UINT32(1);
RangeVar *relrv;
Datum result;
char *values[BTPAGEITEMS_NCOLUMNS];
BTPageOpaque opaque;
HeapTuple tuple;
ItemId id;
FuncCallContext *fctx;
MemoryContext mctx;
struct user_args *uargs = NULL;
if (!superuser())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
(errmsg("must be superuser to use pgstattuple functions"))));
if (SRF_IS_FIRSTCALL())
{
fctx = SRF_FIRSTCALL_INIT();
mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx);
uargs = palloc(sizeof(struct user_args));
uargs->tupd = RelationNameGetTupleDesc(BTPAGEITEMS_TYPE);
uargs->offset = FirstOffsetNumber;
relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
uargs->rel = relation_openrv(relrv, AccessShareLock);
if (!IS_INDEX(uargs->rel) || !IS_BTREE(uargs->rel))
elog(ERROR, "bt_page_items() can be used only on b-tree index.");
/*
* 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 (isOtherTempNamespace(RelationGetNamespace(uargs->rel)))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot access temporary tables of other sessions")));
if (blkno == 0)
elog(ERROR, "Block 0 is a meta page.");
CHECK_RELATION_BLOCK_RANGE(uargs->rel, blkno);
uargs->buffer = ReadBuffer(uargs->rel, blkno);
uargs->page = BufferGetPage(uargs->buffer);
opaque = (BTPageOpaque) PageGetSpecialPointer(uargs->page);
if (P_ISDELETED(opaque))
elog(NOTICE, "bt_page_items(): this page is deleted.");
fctx->max_calls = PageGetMaxOffsetNumber(uargs->page);
fctx->user_fctx = uargs;
MemoryContextSwitchTo(mctx);
}
fctx = SRF_PERCALL_SETUP();
uargs = fctx->user_fctx;
if (fctx->call_cntr < fctx->max_calls)
{
IndexTuple itup;
id = PageGetItemId(uargs->page, uargs->offset);
if (!ItemIdIsValid(id))
elog(ERROR, "Invalid ItemId.");
itup = (IndexTuple) PageGetItem(uargs->page, id);
{
int j = 0;
BlockNumber blkno = BlockIdGetBlockNumber(&(itup->t_tid.ip_blkid));
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", uargs->offset);
values[j] = palloc(32);
snprintf(values[j++], 32, "(%u,%u)", blkno, itup->t_tid.ip_posid);
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", (int) IndexTupleSize(itup));
values[j] = palloc(32);
snprintf(values[j++], 32, "%c", IndexTupleHasNulls(itup) ? 't' : 'f');
values[j] = palloc(32);
snprintf(values[j++], 32, "%c", IndexTupleHasVarwidths(itup) ? 't' : 'f');
{
int off;
char *dump;
char *ptr = (char *) itup + IndexInfoFindDataOffset(itup->t_info);
dump = palloc(IndexTupleSize(itup) * 3);
memset(dump, 0, IndexTupleSize(itup) * 3);
for (off = 0;
off < IndexTupleSize(itup) - IndexInfoFindDataOffset(itup->t_info);
off++)
{
if (dump[0] == '\0')
sprintf(dump, "%02x", *(ptr + off) & 0xff);
else
{
char buf[4];
sprintf(buf, " %02x", *(ptr + off) & 0xff);
strcat(dump, buf);
}
}
values[j] = dump;
}
tuple = BuildTupleFromCStrings(TupleDescGetAttInMetadata(uargs->tupd), values);
result = TupleGetDatum(TupleDescGetSlot(uargs->tupd), tuple);
}
uargs->offset = uargs->offset + 1;
SRF_RETURN_NEXT(fctx, result);
}
else
{
ReleaseBuffer(uargs->buffer);
relation_close(uargs->rel, AccessShareLock);
SRF_RETURN_DONE(fctx);
}
}
/* ------------------------------------------------
* bt_metap()
*
* Get a btree meta-page information
*
* Usage: SELECT * FROM bt_metap('t1_pkey')
* ------------------------------------------------
*/
Datum
bt_metap(PG_FUNCTION_ARGS)
{
text *relname = PG_GETARG_TEXT_P(0);
Buffer buffer;
Relation rel;
RangeVar *relrv;
Datum result;
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);
if (!IS_INDEX(rel) || !IS_BTREE(rel))
elog(ERROR, "bt_metap() can be used only on b-tree index.");
/*
* 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 (isOtherTempNamespace(RelationGetNamespace(rel)))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot access temporary tables of other sessions")));
buffer = ReadBuffer(rel, 0);
{
BTMetaPageData *metad;
TupleDesc tupleDesc;
int j;
char *values[BTMETAP_NCOLUMNS];
HeapTuple tuple;
Page page = BufferGetPage(buffer);
metad = BTPageGetMeta(page);
tupleDesc = RelationNameGetTupleDesc(BTMETAP_TYPE);
j = 0;
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", metad->btm_magic);
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", metad->btm_version);
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", metad->btm_root);
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", metad->btm_level);
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", metad->btm_fastroot);
values[j] = palloc(32);
snprintf(values[j++], 32, "%d", metad->btm_fastlevel);
tuple = BuildTupleFromCStrings(TupleDescGetAttInMetadata(tupleDesc),
values);
result = TupleGetDatum(TupleDescGetSlot(tupleDesc), tuple);
}
ReleaseBuffer(buffer);
relation_close(rel, AccessShareLock);
PG_RETURN_DATUM(result);
}
/* --------------------------------------------------------
* pg_relpages()
*
* Get a number of pages of the table/index.
*
* Usage: SELECT pg_relpages('t1');
* SELECT pg_relpages('t1_pkey');
* --------------------------------------------------------
*/
Datum
pg_relpages(PG_FUNCTION_ARGS)
{
text *relname = PG_GETARG_TEXT_P(0);
Relation rel;
RangeVar *relrv;
int4 relpages;
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);
/* note: this will work OK on non-local temp tables */
relpages = RelationGetNumberOfBlocks(rel);
relation_close(rel, AccessShareLock);
PG_RETURN_INT32(relpages);
}
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