Adapt for SRF(Set Returning Function).
This commit is contained in:
Tatsuo Ishii
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@ -1,27 +1,36 @@
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pgstattuple README 2001/10/01 Tatsuo Ishii
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pgstattuple README 2002/08/22 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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pgstattuple returns the table length, percentage of the "dead"
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tuples of a table and other info. This may help users to determine
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whether vacuum is necessary or not. Here is an example session:
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In addition, pgstattuple prints more detailed information using
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NOTICE.
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test=# \x
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Expanded display is on.
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test=# select * from pgstattuple('pg_proc');
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-[ RECORD 1 ]------+-------
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table_len | 458752
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tuple_count | 1470
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tuple_len | 438896
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tuple_percent | 95.67
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dead_tuple_count | 11
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dead_tuple_len | 3157
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dead_tuple_percent | 0.69
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free_space | 8932
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free_percent | 1.95
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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 table includes 18.75% dead tuples.
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Here are explanations for each column:
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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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table_len -- physical table length in bytes
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tuple_count -- number of live tuples
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tuple_len -- total tuples length in bytes
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tuple_percent -- live tuples in %
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dead_tuple_len -- total dead tuples length in bytes
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dead_tuple_percent -- dead tuples in %
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free_space -- free space in bytes
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free_percent -- free space in %
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2. Installing pgstattuple
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@ -31,12 +40,15 @@ NOTICE: physical length: 0.08MB live tuples: 20 (0.00MB, 1.17%) dead tuples: 32
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3. Using pgstattuple
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pgstattuple can be called as a function:
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pgstattuple may be called as a SRF (set returning function) and is
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defined as follows:
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pgstattuple(TEXT) RETURNS FLOAT8
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CREATE OR REPLACE FUNCTION pgstattuple(text) RETURNS SETOF pgstattuple_view
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AS 'MODULE_PATHNAME', 'pgstattuple'
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LANGUAGE 'c' WITH (isstrict);
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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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The argument is the table name. Note that pgstattuple never
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returns more than 1 tuple.
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4. Notes
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@ -1,34 +1,39 @@
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$Id: README.pgstattuple.euc_jp,v 1.2 2001/12/20 01:56:08 ishii Exp $
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$Id: README.pgstattuple.euc_jp,v 1.3 2002/08/23 08:19:49 ishii Exp $
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pgstattuple README 2001/10/01 石井達夫
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pgstattuple README 2002/08/22 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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要があるという判断の助けになるわけです．これ以外にもいろいろな情報
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が返ります．
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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=# \x
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Expanded display is on.
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test=# select * from pgstattuple('pg_proc');
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-[ RECORD 1 ]------+-------
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table_len | 458752
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tuple_count | 1470
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tuple_len | 438896
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tuple_percent | 95.67
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dead_tuple_count | 11
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dead_tuple_len | 3157
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dead_tuple_percent | 0.69
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free_space | 8932
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free_percent | 1.95
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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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各項目の説明です．
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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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table_len -- テーブルの物理的な大きさ(バイト)
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tuple_count -- タプル数
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tuple_len -- タプル長の合計(バイト)
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tuple_percent -- タプルの割合．table_lenに対するtuple_lenの比率．
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dead_tuple_len -- デッドタプル数
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dead_tuple_percent -- デッドタプルの割合．table_lenに対するtuple_lenの比率．
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free_space -- 再利用可能な領域(バイト)
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free_percent -- 再利用可能な領域．table_lenに対するfree_spaceの比率．
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2. pgstattupleのインストール
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@ -47,12 +52,14 @@ NOTICE: physical length: 0.08MB live tuples: 20 (0.00MB, 1.17%) dead tuples: 32
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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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CREATE OR REPLACE FUNCTION pgstattuple(text) RETURNS SETOF pgstattuple_view
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AS 'MODULE_PATHNAME', 'pgstattuple'
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LANGUAGE 'c' WITH (isstrict);
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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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関数の戻りはpgstattuple_view型です．また，pgstattupleは1行しか行を
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返しません．
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なお，pgstattupleはテーブルにAccessShareLockしかかけないので，
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pgstattuple 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
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@ -69,6 +76,10 @@ NOTICE: physical length: 0.08MB live tuples: 20 (0.00MB, 1.17%) dead tuples: 32
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5. 改訂履歴
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2002/08/23
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SRF(Set Returning Function)を使って7.3用に書き換え．
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2001/12/20 Tom Laneによる修正
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Fix pgstattuple to acquire a read lock on the target table. This
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@ -1,7 +1,7 @@
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/*
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* $Header: /cvsroot/pgsql/contrib/pgstattuple/pgstattuple.c,v 1.6 2002/05/20 23:51:40 tgl Exp $
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* $Header: /cvsroot/pgsql/contrib/pgstattuple/pgstattuple.c,v 1.7 2002/08/23 08:19:49 ishii Exp $
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*
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* Copyright (c) 2001 Tatsuo Ishii
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* Copyright (c) 2001,2002 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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@ -28,6 +28,7 @@
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#include "access/heapam.h"
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#include "access/transam.h"
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#include "catalog/namespace.h"
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#include "funcapi.h"
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#include "utils/builtins.h"
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@ -37,16 +38,22 @@ 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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* returns live/dead tuples info
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*
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* C FUNCTION definition
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* pgstattuple(NAME) returns FLOAT8
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* pgstattuple(TEXT) returns setof pgstattuple_view
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* see pgstattuple.sql for pgstattuple_view
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* ----------
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*/
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#define DUMMY_TUPLE "pgstattuple_view"
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#define NCOLUMNS 9
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#define NCHARS 32
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Datum
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pgstattuple(PG_FUNCTION_ARGS)
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{
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text *relname = PG_GETARG_TEXT_P(0);
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text *relname;
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RangeVar *relrv;
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Relation rel;
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HeapScanDesc scan;
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@ -55,7 +62,7 @@ pgstattuple(PG_FUNCTION_ARGS)
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BlockNumber block = 0; /* next block to count free space in */
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BlockNumber tupblock;
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Buffer buffer;
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double table_len;
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uint64 table_len;
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uint64 tuple_len = 0;
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uint64 dead_tuple_len = 0;
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uint64 tuple_count = 0;
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@ -65,13 +72,67 @@ pgstattuple(PG_FUNCTION_ARGS)
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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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relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname,
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"pgstattuple"));
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FuncCallContext *funcctx;
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int call_cntr;
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int max_calls;
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TupleDesc tupdesc;
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TupleTableSlot *slot;
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AttInMetadata *attinmeta;
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char **values;
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int i;
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Datum result;
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/* stuff done only on the first call of the function */
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if(SRF_IS_FIRSTCALL())
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{
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/* create a function context for cross-call persistence */
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funcctx = SRF_FIRSTCALL_INIT();
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/* total number of tuples to be returned */
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funcctx->max_calls = 1;
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/*
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* Build a tuple description for a pgstattupe_view tuple
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*/
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tupdesc = RelationNameGetTupleDesc(DUMMY_TUPLE);
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/* allocate a slot for a tuple with this tupdesc */
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slot = TupleDescGetSlot(tupdesc);
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/* assign slot to function context */
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funcctx->slot = slot;
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/*
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* Generate attribute metadata needed later to produce tuples from raw
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* C strings
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*/
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attinmeta = TupleDescGetAttInMetadata(tupdesc);
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funcctx->attinmeta = attinmeta;
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}
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/* stuff done on every call of the function */
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funcctx = SRF_PERCALL_SETUP();
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call_cntr = funcctx->call_cntr;
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max_calls = funcctx->max_calls;
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slot = funcctx->slot;
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attinmeta = funcctx->attinmeta;
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/* Are we done? */
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if (call_cntr >= max_calls)
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{
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SRF_RETURN_DONE(funcctx);
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}
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/* open relation */
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relname = PG_GETARG_TEXT_P(0);
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relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname,"pgstattuple"));
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rel = heap_openrv(relrv, AccessShareLock);
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nblocks = RelationGetNumberOfBlocks(rel);
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scan = heap_beginscan(rel, SnapshotAny, 0, NULL);
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/* scan the relation */
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while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
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{
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if (HeapTupleSatisfiesNow(tuple->t_data))
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@ -113,7 +174,7 @@ pgstattuple(PG_FUNCTION_ARGS)
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heap_close(rel, AccessShareLock);
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table_len = (double) nblocks *BLCKSZ;
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table_len = (uint64)nblocks *BLCKSZ;
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if (nblocks == 0)
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{
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@ -128,28 +189,39 @@ pgstattuple(PG_FUNCTION_ARGS)
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free_percent = (double) free_space *100.0 / table_len;
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}
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elog(DEBUG3, "physical length: %.2fMB live tuples: %.0f (%.2fMB, %.2f%%) dead tuples: %.0f (%.2fMB, %.2f%%) free/reusable space: %.2fMB (%.2f%%) overhead: %.2f%%",
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table_len / (1024 * 1024), /* physical length in MB */
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(double) 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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(double) 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
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* 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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* Prepare a values array for storage in our slot.
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* This should be an array of C strings which will
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* be processed later by the appropriate "in" functions.
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*/
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values = (char **) palloc(NCOLUMNS * sizeof(char *));
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for (i=0;i<NCOLUMNS;i++)
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{
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values[i] = (char *) palloc(NCHARS * sizeof(char));
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}
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i = 0;
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snprintf(values[i++], NCHARS, "%lld", table_len);
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snprintf(values[i++], NCHARS, "%lld", tuple_count);
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snprintf(values[i++], NCHARS, "%lld", tuple_len);
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snprintf(values[i++], NCHARS, "%.2f", tuple_percent);
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snprintf(values[i++], NCHARS, "%lld", dead_tuple_count);
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snprintf(values[i++], NCHARS, "%lld", dead_tuple_len);
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snprintf(values[i++], NCHARS, "%.2f", dead_tuple_percent);
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snprintf(values[i++], NCHARS, "%lld", free_space);
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snprintf(values[i++], NCHARS, "%.2f", free_percent);
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/* build a tuple */
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tuple = BuildTupleFromCStrings(attinmeta, values);
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/* make the tuple into a datum */
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result = TupleGetDatum(slot, tuple);
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/* Clean up */
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for (i=0;i<NCOLUMNS;i++)
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{
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pfree(values[i]);
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}
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pfree(values);
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SRF_RETURN_NEXT(funcctx, result);
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}
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@ -1,4 +1,16 @@
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DROP FUNCTION pgstattuple(text);
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CREATE FUNCTION pgstattuple(text) RETURNS float8
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AS 'MODULE_PATHNAME', 'pgstattuple'
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LANGUAGE 'c' WITH (isstrict);
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DROP VIEW pgstattuple_view CASCADE;
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CREATE VIEW pgstattuple_view AS
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SELECT
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0::BIGINT AS table_len, -- physical table length in bytes
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0::BIGINT AS tuple_count, -- number of live tuples
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0::BIGINT AS tuple_len, -- total tuples length in bytes
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0.0::FLOAT AS tuple_percent, -- live tuples in %
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0::BIGINT AS dead_tuple_count, -- number of dead tuples
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0::BIGINT AS dead_tuple_len, -- total dead tuples length in bytes
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0.0::FLOAT AS dead_tuple_percent, -- dead tuples in %
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0::BIGINT AS free_space, -- free space in bytes
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0.0::FLOAT AS free_percent; -- free space in %
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CREATE OR REPLACE FUNCTION pgstattuple(text) RETURNS SETOF pgstattuple_view
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AS 'MODULE_PATHNAME', 'pgstattuple'
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LANGUAGE 'c' WITH (isstrict);
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