Add pgstattuple
This commit is contained in:
Tatsuo Ishii
parent
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# $Header: /cvsroot/pgsql/contrib/Makefile,v 1.28 2001/09/29 03:11:58 momjian Exp $
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# $Header: /cvsroot/pgsql/contrib/Makefile,v 1.29 2001/10/01 01:52:38 ishii Exp $
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subdir = contrib
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top_builddir = ..
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@ -27,6 +27,7 @@ WANTED_DIRS = \
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pg_resetxlog \
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pgbench \
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pgcrypto \
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pgstattuple \
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rserv \
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rtree_gist \
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seg \
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@ -137,6 +137,10 @@ pgcrypto -
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Cryptographic functions
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by Marko Kreen <marko@l-t.ee>
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pgstattuple -
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A function returns the percentage of "dead" tuples in a table
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by Tatsuo Ishii <t-ishii@sra.co.jp>
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retep -
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tools to build retep tools packages
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by Peter T Mount <peter@retep.org.uk>
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@ -0,0 +1,22 @@
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#-------------------------------------------------------------------------
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#
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# pgstattuple Makefile
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#
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# $Id: Makefile,v 1.1 2001/10/01 01:52:38 ishii Exp $
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#
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#-------------------------------------------------------------------------
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subdir = contrib/pgstattuple
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top_builddir = ../..
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include $(top_builddir)/src/Makefile.global
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MODULE_big := pgstattuple
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SRCS += pgstattuple.c
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OBJS := $(SRCS:.c=.o)
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DOCS := README.pgstattuple README.pgstattuple.euc_jp
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DATA_built := pgstattuple.sql
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PG_CPPFLAGS :=
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SHLIB_LINK :=
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include $(top_srcdir)/contrib/contrib-global.mk
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@ -0,0 +1,47 @@
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pgstattuple README 2001/10/01 Tatsuo Ishii
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1. What is pgstattuple?
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pgstattuple returns the percentage of the "dead" tuples of a
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table. This will help users to judge if vacuum is needed.
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In addition, pgstattuple prints more detailed information using
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NOTICE.
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test=# select pgstattuple('tellers');
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NOTICE: physical length: 0.08MB live tuples: 20 (0.00MB, 1.17%) dead tuples: 320 (0.01MB, 18.75%) free/reusable space: 0.01MB (18.06%) overhead: 62.02%
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pgstattuple
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-------------
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18.75
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(1 row)
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Above example shows tellers tables includes 18.75% dead tuples.
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physical length physical size of the table in MB
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live tuples information on the live tuples
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dead tuples information on the dead tuples
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free/reusable space available space
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overhead overhead space
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2. Installing pgstattuple
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$ make
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$ make install
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$ psql -e -f /usr/local/pgsql/share/contrib/pgstattuple.sql test
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3. Using pgstattuple
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pgstattuple can be called as a function:
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pgstattuple(NAME) RETURNS FLOAT8
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The argument is the table name. pgstattuple returns the percentage
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of the "dead" tuples of a table.
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4. Notes
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pgstattuple does not lock the target table at all. So concurrent
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update may affect the result.
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pgstattuple judges a tuple is "dead" if HeapTupleSatisfiesNow()
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returns false.
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@ -0,0 +1,70 @@
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$Id: README.pgstattuple.euc_jp,v 1.1 2001/10/01 01:52:38 ishii Exp $
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pgstattuple README 2001/10/01 石井達夫
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1. pgstattupleとは
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pgstattupleは，UPDATEやDELETEで作られたテーブルのゴミ領域の大きさを，
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テーブル自体の物理的な大きさに対するパーセンテージで返却します．つ
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まり，返却値が大きければ，それだけゴミも多いので，vacuumをかける必
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要があるという判断の助けになるわけです．
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これだけでは情報量が少ないので，NOTICEメッセージでいろんな情報をつ
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いでに出力します．
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test=# select pgstattuple('tellers');
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NOTICE: physical length: 0.08MB live tuples: 20 (0.00MB, 1.17%) dead tuples: 320 (0.01MB, 18.75%) free/reusable space: 0.01MB (18.06%) overhead: 62.02%
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pgstattuple
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-------------
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18.75
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(1 row)
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この実行例では，19%ほどがゴミになっていることが伺えます．NOTICEメッ
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セージの見方も書いておきます．
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physical length テーブルの物理的なサイズをMB単位で表示
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live tuples ゴミではないタプルに関する情報．タプル数，各
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タプルが占める領域の合計，テーブル全体に対する
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比率を表示します．
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dead tuples ゴミになったタプルに関する情報．
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free/reusable space 利用可能な未使用領域や再利用可能領域
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overhead 管理のための領域がテーブル全体に占める比率
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2. pgstattupleのインストール
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PostgreSQLが/usr/local/pgsqlにインストール済であり，testデータベー
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スにpgstattupleをインストールする場合の手順を示します．
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$ make
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$ make install
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ユーザ定義関数を登録します．
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$ psql -e -f /usr/local/pgsql/share/contrib/pgstattuple.sql test
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3. pgstattupleの使い方
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pgstattupleの呼び出し形式は以下です．
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pgstattuple(NAME) RETURNS FLOAT8
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第一引数: テーブル名
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関数の戻りはUPDATEやDELETEで作られたテーブルのゴミ領域の大きさで，
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テーブルの物理的な大きさに対する割合(パーセント)で返却します．
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なお，pgstattupleはテーブルに一切ロックをかけないので，pgstattuple
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を実行中に該当テーブルに更新や削除が発生すると，正しくない結果を返
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す可能性があります．
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4. pgstattupleのライセンス条件について
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pgstattuple.cの冒頭に書いてある通りです．また，pgstattuple は完全に無保
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証です．pgstattuple を使用したことによって生じるいかなる結果に関して
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も責任を負いません．
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5. 改訂履歴
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2001/10/01 PostgreSQL 7.2 用contrib moduleに登録
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2001/08/30 pgstattuple バージョン 0.1リリース
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@ -0,0 +1,131 @@
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/*
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* $Header: /cvsroot/pgsql/contrib/pgstattuple/pgstattuple.c,v 1.1 2001/10/01 01:52:38 ishii Exp $
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*
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* Copyright (c) 2001 Tatsuo Ishii
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*
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* Permission to use, copy, modify, and distribute this software and
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* its documentation for any purpose, without fee, and without a
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* written agreement is hereby granted, provided that the above
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* copyright notice and this paragraph and the following two
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* paragraphs appear in all copies.
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*
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE TO ANY PARTY FOR DIRECT,
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* INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
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* LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
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* DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* THE AUTHOR SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS
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* IS" BASIS, AND THE AUTHOR HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE,
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* SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*/
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#include "postgres.h"
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#include "fmgr.h"
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#include "access/heapam.h"
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#include "access/transam.h"
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PG_FUNCTION_INFO_V1(pgstattuple);
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extern Datum pgstattuple(PG_FUNCTION_ARGS);
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/* ----------
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* pgstattuple:
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* returns the percentage of dead tuples
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*
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* C FUNCTION definition
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* pgstattuple(NAME) returns FLOAT8
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* ----------
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*/
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Datum
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pgstattuple(PG_FUNCTION_ARGS)
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{
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Name p = PG_GETARG_NAME(0);
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Relation rel;
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HeapScanDesc scan;
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HeapTuple tuple;
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BlockNumber nblocks;
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BlockNumber block = InvalidBlockNumber;
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double table_len;
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uint64 tuple_len = 0;
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uint64 dead_tuple_len = 0;
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uint32 tuple_count = 0;
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uint32 dead_tuple_count = 0;
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double tuple_percent;
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double dead_tuple_percent;
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Buffer buffer = InvalidBuffer;
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uint64 free_space = 0; /* free/reusable space in bytes */
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double free_percent; /* free/reusable space in % */
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rel = heap_openr(NameStr(*p), NoLock);
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nblocks = RelationGetNumberOfBlocks(rel);
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scan = heap_beginscan(rel, false, SnapshotAny, 0, NULL);
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while ((tuple = heap_getnext(scan,0)))
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{
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if (HeapTupleSatisfiesNow(tuple->t_data))
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{
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tuple_len += tuple->t_len;
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tuple_count++;
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}
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else
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{
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dead_tuple_len += tuple->t_len;
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dead_tuple_count++;
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}
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if (!BlockNumberIsValid(block) ||
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block != BlockIdGetBlockNumber(&tuple->t_self.ip_blkid))
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{
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block = BlockIdGetBlockNumber(&tuple->t_self.ip_blkid);
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buffer = ReadBuffer(rel, block);
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free_space += PageGetFreeSpace((Page)BufferGetPage(buffer));
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ReleaseBuffer(buffer);
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}
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}
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heap_endscan(scan);
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heap_close(rel, NoLock);
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table_len = (double)nblocks*BLCKSZ;
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if (nblocks == 0)
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{
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tuple_percent = 0.0;
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dead_tuple_percent = 0.0;
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free_percent = 0.0;
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}
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else
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{
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tuple_percent = (double)tuple_len*100.0/table_len;
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dead_tuple_percent = (double)dead_tuple_len*100.0/table_len;
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free_percent = (double)free_space*100.0/table_len;
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}
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elog(NOTICE,"physical length: %.2fMB live tuples: %u (%.2fMB, %.2f%%) dead tuples: %u (%.2fMB, %.2f%%) free/reusable space: %.2fMB (%.2f%%) overhead: %.2f%%",
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table_len/1024/1024, /* phsical length in MB */
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tuple_count, /* number of live tuples */
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(double)tuple_len/1024/1024, /* live tuples in MB */
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tuple_percent, /* live tuples in % */
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dead_tuple_count, /* number of dead tuples */
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(double)dead_tuple_len/1024/1024, /* dead tuples in MB */
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dead_tuple_percent, /* dead tuples in % */
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(double)free_space/1024/1024, /* free/available space in MB */
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free_percent, /* free/available space in % */
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/* overhead in % */
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(nblocks == 0)?0.0: 100.0
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- tuple_percent
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- dead_tuple_percent
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- free_percent);
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PG_RETURN_FLOAT8(dead_tuple_percent);
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}
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@ -0,0 +1,4 @@
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DROP FUNCTION pgstattuple(NAME);
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CREATE FUNCTION pgstattuple(NAME) RETURNS FLOAT8
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AS 'MODULE_PATHNAME', 'pgstattuple'
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LANGUAGE 'c' WITH (isstrict);
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