Add new contrib function pgrowlocks. See README.pgrowlocks for more details.
This commit is contained in:
Tatsuo Ishii
parent
044c3b4615
commit
66126f9687
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#-------------------------------------------------------------------------
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#
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# pgrowlocks Makefile
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#
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# $PostgreSQL: pgsql/contrib/pgrowlocks/Makefile,v 1.1 2006/04/23 01:12:58 ishii Exp $
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#
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#-------------------------------------------------------------------------
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SRCS = pgrowlocks.c
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MODULE_big = pgrowlocks
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OBJS = $(SRCS:.c=.o)
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DOCS = README.pgrowlocks README.pgrowlocks.euc_jp
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DATA_built = pgrowlocks.sql
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ifdef USE_PGXS
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PGXS = $(shell pg_config --pgxs)
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include $(PGXS)
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else
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subdir = contrib/pgrowlocks
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top_builddir = ../..
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include $(top_builddir)/src/Makefile.global
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include $(top_srcdir)/contrib/contrib-global.mk
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endif
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$PostgreSQL: pgsql/contrib/pgrowlocks/README.pgrowlocks,v 1.1 2006/04/23 01:12:58 ishii Exp $
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pgrowlocks README Tatsuo Ishii
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1. What is pgrowlocks?
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pgrowlocks shows row locking information for specified table.
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pgrowlocks returns following data type:
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CREATE TYPE pgrowlocks_type AS (
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locked_row TID, -- row TID
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lock_type TEXT, -- lock type
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locker XID, -- locking XID
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multi bool, -- multi XID?
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xids xid[], -- multi XIDs
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pids INTEGER[] -- locker's process id
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);
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Here is a sample execution of pgrowlocks:
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test=# SELECT * FROM pgrowlocks('t1');
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locked_row | lock_type | locker | multi | xids | pids
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------------+-----------+--------+-------+-----------+---------------
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(0,1) | Shared | 19 | t | {804,805} | {29066,29068}
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(0,2) | Shared | 19 | t | {804,805} | {29066,29068}
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(0,3) | Exclusive | 804 | f | {804} | {29066}
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(0,4) | Exclusive | 804 | f | {804} | {29066}
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(4 rows)
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locked_row -- tuple ID(TID) of each locked rows
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lock_type -- "Shared" for shared lock, "Exclusive" for exclusive lock
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locker -- transaction ID of locker (note 1)
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multi -- "t" if locker is a multi transaction, otherwise "f"
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xids -- XIDs of lockers (note 2)
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pids -- process ids of locking backends
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note1: if the locker is multi transaction, it represents the multi ID
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note2: if the locker is multi, multiple data are shown
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2. Installing pgrowlocks
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Installing pgrowlocks requires PostgreSQL 8.0 or later source tree.
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$ cd /usr/local/src/postgresql-8.1/contrib
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$ tar xfz /tmp/pgrowlocks-1.0.tar.gz
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If you are using PostgreSQL 8.0, you need to modify pgrowlocks source code.
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Around line 61, you will see:
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#undef MAKERANGEVARFROMNAMELIST_HAS_TWO_ARGS
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change this to:
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#define MAKERANGEVARFROMNAMELIST_HAS_TWO_ARGS
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$ make
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$ make install
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$ psql -e -f pgrowlocks.sql test
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3. How to use pgrowlocks
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The calling sequence for pgrowlocks is as follows:
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CREATE OR REPLACE FUNCTION pgrowlocks(text) RETURNS pgrowlocks_type
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AS 'MODULE_PATHNAME', 'pgrowlocks'
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LANGUAGE 'c' WITH (isstrict);
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The parameter is a name of table. pgrowlocks returns type pgrowlocks_type.
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pgrowlocks grab AccessShareLock for the target table and read each
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row one by one to get the row locking information. You should
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notice that:
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1) if the table is exclusive locked by someone else, pgrowlocks
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will be blocked.
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2) pgrowlocks may show incorrect information if there's a new
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lock or a lock is freeed while its execution.
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pgrowlocks does not show the contents of locked rows. If you want
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to take a look at the row contents at the same time, you could do
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something like this:
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SELECT * FROM accounts AS a, pgrowlocks('accounts') AS p WHERE p.locked_ row = a.ctid;
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4. License
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pgrowlocks is distribute under (modified) BSD license described in
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the source file.
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5. History
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2006/03/21 pgrowlocks version 1.1 released (tested on 8.2 current)
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2005/08/22 pgrowlocks version 1.0 released
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$PostgreSQL: pgsql/contrib/pgrowlocks/README.pgrowlocks.euc_jp,v 1.1 2006/04/23 01:12:58 ishii Exp $
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pgrowlocks README 石井達夫
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1. pgrowlocksとは
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pgrowlocksは，指定されたテーブルの行ロックに関する情報を表示します．
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pgrowlocksの返す型は，以下のようになります．
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CREATE TYPE pgrowlocks_type AS (
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locked_row TID, -- row TID
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lock_type TEXT, -- lock type
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locker XID, -- locking XID
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multi bool, -- multi XID?
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xids xid[], -- multi XIDs
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pids INTEGER[] -- locker's process id
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);
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実行例を示します．
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test=# SELECT * FROM pgrowlocks('t1');
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locked_row | lock_type | locker | multi | xids | pids
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------------+-----------+--------+-------+-----------+---------------
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(0,1) | Shared | 19 | t | {804,805} | {29066,29068}
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(0,2) | Shared | 19 | t | {804,805} | {29066,29068}
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(0,3) | Exclusive | 804 | f | {804} | {29066}
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(0,4) | Exclusive | 804 | f | {804} | {29066}
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(4 rows)
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各項目の説明です．
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locked_row -- ロックされた行のタプルID(TID)
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lock_type -- 共有ロックなら"Shared"，排他ロックなら"Exclusive"
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locker -- ロックをかけているトランザクションID[注1]
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multi -- lockerがマルチトランザクションならtそうでなければf
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xids -- ロックをかけているトランザクションID[注2]
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pids -- ロックをかけているバックエンドプロセスのプロセスID[注2]
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[注1: lockerがマルチなら，トランザクションIDではなくてマルチIDになり
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ます．]
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[注2: lockerがマルチの場合，複数のデータが表示されます．]
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2. pgrowlocksのインストール
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pgrowlocksのインストールには，PostgreSQLをインストールしたときのソー
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スツリーが必要です．今のところ対応しているバージョンはPostgreSQL
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8.0以降です．
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ここではPostgreSQLのソースは/usr/local/src/postgresql-8.1/に展開さ
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れているものとします．
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1) pgrowlocksのソースを展開します．ソースファイルは
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/tmp/pgrowlocks-1.0.tar.gzに置いてあるものとします．
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$ cd /usr/local/src/postgresql-8.1/contrib
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$ tar xfz pgrowlocks-1.0.tar.gz
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2) PostgreSQL 8.0の場合は，ソースの一部に修正が必要です．
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pgrowlocks.cの61行目辺りに
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#undef MAKERANGEVARFROMNAMELIST_HAS_TWO_ARGS
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というのがあるので，これを
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#define MAKERANGEVARFROMNAMELIST_HAS_TWO_ARGS
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に書き換えます(undef->defineにします)．
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3) コンパイルして関数の共有ライブラリをインストールします．
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$ make
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$ make install
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4) 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/pgrowlocks.sql test
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この例では"test"というデータベースに登録していますが，もし他のデー
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タベースに登録する場合はここを読み替えてください．
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3. pgrowlocksの使い方
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pgrowlocksの呼び出し形式は以下です．
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CREATE OR REPLACE FUNCTION pgrowlocks(text) RETURNS pgrowlocks_type
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AS 'MODULE_PATHNAME', 'pgrowlocks'
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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pgrowlocks_type型です．
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pgrowlocksはテーブルにAccessShareLockロックをかけ，1行ずつ読み出し
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ては行ロックがかかっているかどうかチェックします．以下の点に注意し
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てください．
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1) 該当テーブルに排他ロックがかかっていると，pgrowlocksの実行はブロッ
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クされます．
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2) pgrowlocksの実行中に新たにかかったり，解除された行ロックに関する
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情報はpgrowlocksの実行結果に反映されていない可能性があります．
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pgrowlocksはロックされた行の内容は表示しません．行内容を見たい場合
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は，テーブルをpgrowlocksのlocked_rows列で結合します．例を示します．
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SELECT * FROM accounts AS a, pgrowlocks('accounts') AS p WHERE p.locked_ row = a.ctid;
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4. pgrowlocksのライセンス条件について
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pgrowlocks.cの冒頭に書いてある通りです(修正BSDライセンスに準じてい
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ます)．また，pgrowlocks は完全に無保証です．pgrowlocks を使用したこ
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とによって生じるいかなる結果に関しても責任を負いません．
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5. 改訂履歴
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2006/03/21 pgrowlocks バージョン 1.1リリース(8.2 currentでテスト)
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2005/08/22 pgrowlocks バージョン 1.0リリース
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/*
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* $PostgreSQL: pgsql/contrib/pgrowlocks/pgrowlocks.c,v 1.1 2006/04/23 01:12:58 ishii Exp $
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*
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* Copyright (c) 2005-2006 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 "funcapi.h"
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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 "catalog/pg_type.h"
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#include "storage/proc.h"
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#include "utils/builtins.h"
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#ifdef HEAP_XMAX_SHARED_LOCK
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#include "access/multixact.h"
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#include "storage/procarray.h"
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#endif
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PG_FUNCTION_INFO_V1(pgrowlocks);
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extern Datum pgrowlocks(PG_FUNCTION_ARGS);
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/* ----------
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* pgrowlocks:
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* returns tids of rows being locked
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*
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* C FUNCTION definition
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* pgrowlocks(text) returns set of pgrowlocks_type
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* see pgrowlocks.sql for pgrowlocks_type
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* ----------
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*/
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#define DUMMY_TUPLE "public.pgrowlocks_type"
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#define NCHARS 32
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/*
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* define this if makeRangeVarFromNameList() has two arguments. As far
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* as I know, this only happens in 8.0.x.
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*/
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#undef MAKERANGEVARFROMNAMELIST_HAS_TWO_ARGS
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typedef struct {
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HeapScanDesc scan;
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int ncolumns;
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} MyData;
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Datum
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pgrowlocks(PG_FUNCTION_ARGS)
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{
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FuncCallContext *funcctx;
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HeapScanDesc scan;
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HeapTuple tuple;
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TupleDesc tupdesc;
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AttInMetadata *attinmeta;
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Datum result;
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MyData *mydata;
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Relation rel;
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if (SRF_IS_FIRSTCALL())
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{
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text *relname;
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RangeVar *relrv;
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MemoryContext oldcontext;
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funcctx = SRF_FIRSTCALL_INIT();
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oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
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tupdesc = RelationNameGetTupleDesc(DUMMY_TUPLE);
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attinmeta = TupleDescGetAttInMetadata(tupdesc);
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funcctx->attinmeta = attinmeta;
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relname = PG_GETARG_TEXT_P(0);
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#ifdef MAKERANGEVARFROMNAMELIST_HAS_TWO_ARGS
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relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname, "pgrowlocks"));
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#else
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relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
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#endif
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rel = heap_openrv(relrv, AccessShareLock);
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scan = heap_beginscan(rel, SnapshotNow, 0, NULL);
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mydata = palloc(sizeof(*mydata));
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mydata->scan = scan;
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mydata->ncolumns = tupdesc->natts;
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funcctx->user_fctx = mydata;
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MemoryContextSwitchTo(oldcontext);
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}
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funcctx = SRF_PERCALL_SETUP();
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attinmeta = funcctx->attinmeta;
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mydata = (MyData *)funcctx->user_fctx;
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scan = mydata->scan;
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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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/* must hold a buffer lock to call HeapTupleSatisfiesUpdate */
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LockBuffer(scan->rs_cbuf, BUFFER_LOCK_SHARE);
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if (HeapTupleSatisfiesUpdate(tuple->t_data, GetCurrentCommandId(), scan->rs_cbuf)
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== HeapTupleBeingUpdated)
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{
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char **values;
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int i;
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values = (char **) palloc(mydata->ncolumns * sizeof(char *));
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i = 0;
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values[i++] = (char *)DirectFunctionCall1(tidout, PointerGetDatum(&tuple->t_self));
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#ifdef HEAP_XMAX_SHARED_LOCK
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if (tuple->t_data->t_infomask & HEAP_XMAX_SHARED_LOCK)
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values[i++] = pstrdup("Shared");
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else
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values[i++] = pstrdup("Exclusive");
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#else
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values[i++] = pstrdup("Exclusive");
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#endif
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values[i] = palloc(NCHARS*sizeof(char));
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snprintf(values[i++], NCHARS, "%d", HeapTupleHeaderGetXmax(tuple->t_data));
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#ifdef HEAP_XMAX_SHARED_LOCK
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if (tuple->t_data->t_infomask & HEAP_XMAX_IS_MULTI)
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{
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TransactionId *xids;
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int nxids;
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int j;
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int isValidXid = 0; /* any valid xid ever exists? */
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values[i++] = pstrdup("true");
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nxids = GetMultiXactIdMembers(HeapTupleHeaderGetXmax(tuple->t_data), &xids);
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if (nxids == -1)
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{
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elog(ERROR, "GetMultiXactIdMembers returns error");
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}
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values[i] = palloc(NCHARS*nxids);
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values[i+1] = palloc(NCHARS*nxids);
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strcpy(values[i], "{");
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strcpy(values[i+1], "{");
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for (j=0;j<nxids;j++)
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{
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char buf[NCHARS];
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if (TransactionIdIsInProgress(xids[j]))
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{
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if (isValidXid)
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{
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strcat(values[i], ",");
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strcat(values[i+1], ",");
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}
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snprintf(buf, NCHARS, "%d", xids[j]);
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strcat(values[i], buf);
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snprintf(buf, NCHARS, "%d", BackendXidGetPid(xids[j]));
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strcat(values[i+1], buf);
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isValidXid = 1;
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}
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}
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strcat(values[i], "}");
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strcat(values[i+1], "}");
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i++;
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}
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else
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{
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values[i++] = pstrdup("false");
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values[i] = palloc(NCHARS*sizeof(char));
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snprintf(values[i++], NCHARS, "{%d}", HeapTupleHeaderGetXmax(tuple->t_data));
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values[i] = palloc(NCHARS*sizeof(char));
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snprintf(values[i++], NCHARS, "{%d}", BackendXidGetPid(HeapTupleHeaderGetXmax(tuple->t_data)));
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}
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#else
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values[i++] = pstrdup("false");
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values[i++] = pstrdup("{}");
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values[i++] = pstrdup("{}");
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#endif
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LockBuffer(scan->rs_cbuf, BUFFER_LOCK_UNLOCK);
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/* build a tuple */
|
||||
tuple = BuildTupleFromCStrings(attinmeta, values);
|
||||
|
||||
/* make the tuple into a datum */
|
||||
result = HeapTupleGetDatum(tuple);
|
||||
|
||||
/* Clean up */
|
||||
for (i = 0; i < mydata->ncolumns; i++)
|
||||
pfree(values[i]);
|
||||
pfree(values);
|
||||
|
||||
SRF_RETURN_NEXT(funcctx, result);
|
||||
}
|
||||
else
|
||||
{
|
||||
LockBuffer(scan->rs_cbuf, BUFFER_LOCK_UNLOCK);
|
||||
}
|
||||
}
|
||||
|
||||
heap_endscan(scan);
|
||||
heap_close(scan->rs_rd, AccessShareLock);
|
||||
|
||||
SRF_RETURN_DONE(funcctx);
|
||||
}
|
||||
|
|
@ -0,0 +1,16 @@
|
|||
-- Adjust this setting to control where the objects get created.
|
||||
SET search_path = public;
|
||||
|
||||
CREATE TYPE pgrowlocks_type AS (
|
||||
locked_row TID, -- row TID
|
||||
lock_type TEXT, -- lock type
|
||||
locker XID, -- locking XID
|
||||
multi bool, -- multi XID?
|
||||
xids xid[], -- multi XIDs
|
||||
pids INTEGER[] -- locker's process id
|
||||
);
|
||||
|
||||
CREATE OR REPLACE FUNCTION pgrowlocks(text)
|
||||
RETURNS setof pgrowlocks_type
|
||||
AS 'MODULE_PATHNAME', 'pgrowlocks'
|
||||
LANGUAGE 'C' STRICT;
|
||||
Loading…
Reference in New Issue