mirror of https://github.com/postgres/postgres
Tatsuo Ishii
25 years ago
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95d4821b1c
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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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