Add new contrib function pgrowlocks. See README.pgrowlocks for more details.

contrib/pgrowlocks/Makefile

+#-------------------------------------------------------------------------
+#
+# pgrowlocks Makefile
+#
+# $PostgreSQL: pgsql/contrib/pgrowlocks/Makefile,v 1.1 2006/04/23 01:12:58 ishii Exp $
+#
+#-------------------------------------------------------------------------
+
+SRCS		= pgrowlocks.c
+
+MODULE_big	= pgrowlocks
+OBJS		= $(SRCS:.c=.o)
+DOCS		= README.pgrowlocks README.pgrowlocks.euc_jp
+DATA_built	= pgrowlocks.sql
+
+ifdef USE_PGXS
+PGXS = $(shell pg_config --pgxs)
+include $(PGXS)
+else
+subdir = contrib/pgrowlocks
+top_builddir = ../..
+include $(top_builddir)/src/Makefile.global
+include $(top_srcdir)/contrib/contrib-global.mk
+endif
+

contrib/pgrowlocks/README.pgrowlocks

+$PostgreSQL: pgsql/contrib/pgrowlocks/README.pgrowlocks,v 1.1 2006/04/23 01:12:58 ishii Exp $
+
+pgrowlocks README			Tatsuo Ishii
+
+1. What is pgrowlocks?
+
+   pgrowlocks shows row locking information for specified table.
+
+   pgrowlocks returns following data type:
+
+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
+);
+
+  Here is a sample execution of pgrowlocks:
+
+test=# SELECT * FROM pgrowlocks('t1');
+ locked_row | lock_type | locker | multi |   xids    |     pids      
+------------+-----------+--------+-------+-----------+---------------
+      (0,1) | Shared    |     19 | t     | {804,805} | {29066,29068}
+      (0,2) | Shared    |     19 | t     | {804,805} | {29066,29068}
+      (0,3) | Exclusive |    804 | f     | {804}     | {29066}
+      (0,4) | Exclusive |    804 | f     | {804}     | {29066}
+(4 rows)
+
+  locked_row		-- tuple ID(TID) of each locked rows
+  lock_type		-- "Shared" for shared lock, "Exclusive" for exclusive lock
+  locker		-- transaction ID of locker (note 1)
+  multi			-- "t" if locker is a multi transaction, otherwise "f"
+  xids			-- XIDs of lockers (note 2)
+  pids			-- process ids of locking backends
+
+  note1: if the locker is multi transaction, it represents the multi ID
+
+  note2: if the locker is multi, multiple data are shown
+
+2. Installing pgrowlocks
+
+   Installing pgrowlocks requires PostgreSQL 8.0 or later source tree.
+
+      $ cd /usr/local/src/postgresql-8.1/contrib
+      $ tar xfz /tmp/pgrowlocks-1.0.tar.gz
+
+   If you are using PostgreSQL 8.0, you need to modify pgrowlocks source code.
+   Around line 61, you will see:
+
+      #undef MAKERANGEVARFROMNAMELIST_HAS_TWO_ARGS
+
+   change this to:
+
+      #define MAKERANGEVARFROMNAMELIST_HAS_TWO_ARGS
+
+      $ make
+      $ make install
+
+      $ psql -e -f pgrowlocks.sql test
+
+3. How to use pgrowlocks
+
+   The calling sequence for pgrowlocks is as follows:
+
+   CREATE OR REPLACE FUNCTION pgrowlocks(text) RETURNS pgrowlocks_type
+     AS 'MODULE_PATHNAME', 'pgrowlocks'
+     LANGUAGE 'c' WITH (isstrict);
+
+   The parameter is a name of table. pgrowlocks returns type pgrowlocks_type.
+
+   pgrowlocks grab AccessShareLock for the target table and read each
+   row one by one to get the row locking information. You should
+   notice that:
+
+   1) if the table is exclusive locked by someone else, pgrowlocks
+      will be blocked.
+
+   2) pgrowlocks may show incorrect information if there's a new
+      lock or a lock is freeed while its execution.
+
+   pgrowlocks does not show the contents of locked rows. If you want
+   to take a look at the row contents at the same time, you could do
+   something like this:
+
+   SELECT * FROM accounts AS a, pgrowlocks('accounts') AS p WHERE p.locked_ row = a.ctid;
+
+
+4. License
+
+   pgrowlocks is distribute under (modified) BSD license described in
+   the source file.
+
+5. History
+
+   2006/03/21 pgrowlocks version 1.1 released (tested on 8.2 current)
+   2005/08/22 pgrowlocks version 1.0 released

contrib/pgrowlocks/README.pgrowlocks.euc_jp

+$PostgreSQL: pgsql/contrib/pgrowlocks/README.pgrowlocks.euc_jp,v 1.1 2006/04/23 01:12:58 ishii Exp $
+
+pgrowlocks README		石井達夫
+
+1. pgrowlocksとは
+
+   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．
+
+   pgrowlocksの返す型は，以下のようになります．
+
+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
+);
+
+  実行例を示します．
+
+test=# SELECT * FROM pgrowlocks('t1');
+ locked_row | lock_type | locker | multi |   xids    |     pids      
+------------+-----------+--------+-------+-----------+---------------
+      (0,1) | Shared    |     19 | t     | {804,805} | {29066,29068}
+      (0,2) | Shared    |     19 | t     | {804,805} | {29066,29068}
+      (0,3) | Exclusive |    804 | f     | {804}     | {29066}
+      (0,4) | Exclusive |    804 | f     | {804}     | {29066}
+(4 rows)
+
+  各項目の説明です．
+
+  locked_row		-- ロックされた行のタプルID(TID)
+  lock_type		-- 共有ロックなら"Shared"，排他ロックなら"Exclusive"
+  locker		-- ロックをかけているトランザクションID[注1]
+  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
+  xids			-- ロックをかけているトランザクションID[注2]
+  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]
+
+  [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
+  ます．]
+
+  [注2: lockerがマルチの場合，複数のデータが表示されます．]
+
+2. pgrowlocksのインストール
+
+   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
+   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
+   8.0以降です．
+
+   ここではPostgreSQLのソースは/usr/local/src/postgresql-8.1/に展開さ
+   れているものとします．
+
+   1) pgrowlocksのソースを展開します．ソースファイルは
+      /tmp/pgrowlocks-1.0.tar.gzに置いてあるものとします．
+
+      $ cd /usr/local/src/postgresql-8.1/contrib
+      $ tar xfz pgrowlocks-1.0.tar.gz
+
+   2) PostgreSQL 8.0の場合は，ソースの一部に修正が必要です．
+      pgrowlocks.cの61行目辺りに
+
+      #undef MAKERANGEVARFROMNAMELIST_HAS_TWO_ARGS
+
+      というのがあるので，これを
+
+      #define MAKERANGEVARFROMNAMELIST_HAS_TWO_ARGS
+
+      に書き換えます(undef->defineにします)．
+
+   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．
+
+      $ make
+      $ make install
+
+   4) ユーザ定義関数を登録します．
+
+      $ psql -e -f /usr/local/pgsql/share/contrib/pgrowlocks.sql test
+
+      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
+      タベースに登録する場合はここを読み替えてください．
+
+3. pgrowlocksの使い方
+
+   pgrowlocksの呼び出し形式は以下です．
+
+   CREATE OR REPLACE FUNCTION pgrowlocks(text) RETURNS pgrowlocks_type
+     AS 'MODULE_PATHNAME', 'pgrowlocks'
+     LANGUAGE 'c' WITH (isstrict);
+
+   第一引数: テーブル名
+
+   関数の戻りはpgrowlocks_type型です．
+
+   pgrowlocksはテーブルにAccessShareLockロックをかけ，1行ずつ読み出し
+   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
+   てください．
+
+   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
+      クされます．
+
+   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
+      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．
+
+
+   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
+   は，テーブルをpgrowlocksのlocked_rows列で結合します．例を示します．
+
+   SELECT * FROM accounts AS a, pgrowlocks('accounts') AS p WHERE p.locked_ row = a.ctid;
+
+
+4. pgrowlocksのライセンス条件について
+
+   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
+   ます)．また，pgrowlocks は完全に無保証です．pgrowlocks を使用したこ
+   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．
+
+5. 改訂履歴
+
+   2006/03/21 pgrowlocks バージョン 1.1リリース(8.2 currentでテスト)
+   2005/08/22 pgrowlocks バージョン 1.0リリース

contrib/pgrowlocks/pgrowlocks.c

+/*
+ * $PostgreSQL: pgsql/contrib/pgrowlocks/pgrowlocks.c,v 1.1 2006/04/23 01:12:58 ishii Exp $
+ *
+ * Copyright (c) 2005-2006	Tatsuo Ishii
+ *
+ * Permission to use, copy, modify, and distribute this software and
+ * its documentation for any purpose, without fee, and without a
+ * written agreement is hereby granted, provided that the above
+ * copyright notice and this paragraph and the following two
+ * paragraphs appear in all copies.
+ *
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE TO ANY PARTY FOR DIRECT,
+ * INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
+ * LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
+ * DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * THE AUTHOR SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS
+ * IS" BASIS, AND THE AUTHOR HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE,
+ * SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ */
+
+#include "postgres.h"
+
+#include "funcapi.h"
+#include "access/heapam.h"
+#include "access/transam.h"
+#include "catalog/namespace.h"
+#include "catalog/pg_type.h"
+#include "storage/proc.h"
+#include "utils/builtins.h"
+
+#ifdef HEAP_XMAX_SHARED_LOCK
+#include "access/multixact.h"
+#include "storage/procarray.h"
+#endif
+
+PG_FUNCTION_INFO_V1(pgrowlocks);
+
+extern Datum pgrowlocks(PG_FUNCTION_ARGS);
+
+/* ----------
+ * pgrowlocks:
+ * returns tids of rows being locked
+ *
+ * C FUNCTION definition
+ * pgrowlocks(text) returns set of pgrowlocks_type
+ * see pgrowlocks.sql for pgrowlocks_type
+ * ----------
+ */
+
+#define DUMMY_TUPLE "public.pgrowlocks_type"
+#define NCHARS 32
+
+/*
+ * define this if makeRangeVarFromNameList() has two arguments. As far
+ * as I know, this only happens in 8.0.x.
+ */
+#undef MAKERANGEVARFROMNAMELIST_HAS_TWO_ARGS
+
+typedef struct {
+	HeapScanDesc scan;
+	int ncolumns;
+} MyData;
+
+Datum
+pgrowlocks(PG_FUNCTION_ARGS)
+{
+	FuncCallContext *funcctx;
+	HeapScanDesc scan;
+	HeapTuple	tuple;
+	TupleDesc	tupdesc;
+	AttInMetadata *attinmeta;
+	Datum		result;
+	MyData *mydata;
+	Relation	rel;
+
+	if (SRF_IS_FIRSTCALL())
+	{
+		text	   *relname;
+		RangeVar   *relrv;
+		MemoryContext oldcontext;
+
+		funcctx = SRF_FIRSTCALL_INIT();
+		oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
+
+		tupdesc = RelationNameGetTupleDesc(DUMMY_TUPLE);
+		attinmeta = TupleDescGetAttInMetadata(tupdesc);
+		funcctx->attinmeta = attinmeta;
+
+		relname = PG_GETARG_TEXT_P(0);
+#ifdef MAKERANGEVARFROMNAMELIST_HAS_TWO_ARGS
+		relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname,												 "pgrowlocks"));
+
+#else
+		relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
+#endif
+		rel = heap_openrv(relrv, AccessShareLock);
+		scan = heap_beginscan(rel, SnapshotNow, 0, NULL);
+		mydata = palloc(sizeof(*mydata));
+		mydata->scan = scan;
+		mydata->ncolumns = tupdesc->natts;
+		funcctx->user_fctx = mydata;
+
+		MemoryContextSwitchTo(oldcontext);
+	}
+
+	funcctx = SRF_PERCALL_SETUP();
+	attinmeta = funcctx->attinmeta;
+	mydata = (MyData *)funcctx->user_fctx;
+	scan = mydata->scan;
+
+	/* scan the relation */
+	while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
+	{
+		/* must hold a buffer lock to call HeapTupleSatisfiesUpdate */
+		LockBuffer(scan->rs_cbuf, BUFFER_LOCK_SHARE);
+
+		if (HeapTupleSatisfiesUpdate(tuple->t_data, GetCurrentCommandId(), scan->rs_cbuf)
+		    == HeapTupleBeingUpdated)
+		{
+
+			char **values;
+			int i;
+
+			values = (char **) palloc(mydata->ncolumns * sizeof(char *));
+
+			i = 0;
+			values[i++] = (char *)DirectFunctionCall1(tidout, PointerGetDatum(&tuple->t_self));
+
+#ifdef HEAP_XMAX_SHARED_LOCK
+			if (tuple->t_data->t_infomask & HEAP_XMAX_SHARED_LOCK)
+				values[i++] = pstrdup("Shared");
+			else
+				values[i++] = pstrdup("Exclusive");
+#else
+			values[i++] = pstrdup("Exclusive");
+#endif
+			values[i] = palloc(NCHARS*sizeof(char));
+			snprintf(values[i++], NCHARS, "%d", HeapTupleHeaderGetXmax(tuple->t_data));
+#ifdef HEAP_XMAX_SHARED_LOCK
+			if (tuple->t_data->t_infomask & HEAP_XMAX_IS_MULTI)
+			{
+				TransactionId *xids;
+				int nxids;
+				int j;
+				int isValidXid = 0;		/* any valid xid ever exists? */
+
+				values[i++] = pstrdup("true");
+				nxids = GetMultiXactIdMembers(HeapTupleHeaderGetXmax(tuple->t_data), &xids);
+				if (nxids == -1)
+				{
+					elog(ERROR, "GetMultiXactIdMembers returns error");
+				}
+
+				values[i] = palloc(NCHARS*nxids);
+				values[i+1] = palloc(NCHARS*nxids);
+				strcpy(values[i], "{");
+				strcpy(values[i+1], "{");
+
+				for (j=0;j<nxids;j++)
+				{
+					char buf[NCHARS];
+
+					if (TransactionIdIsInProgress(xids[j]))
+					{
+						if (isValidXid)
+						{
+							strcat(values[i], ",");
+							strcat(values[i+1], ",");
+						}
+						snprintf(buf, NCHARS, "%d", xids[j]);
+						strcat(values[i], buf);
+						snprintf(buf, NCHARS, "%d", BackendXidGetPid(xids[j]));
+						strcat(values[i+1], buf);
+
+						isValidXid = 1;
+					}
+				}
+
+				strcat(values[i], "}");
+				strcat(values[i+1], "}");
+				i++;
+			}
+			else
+			{
+				values[i++] = pstrdup("false");
+				values[i] = palloc(NCHARS*sizeof(char));
+				snprintf(values[i++], NCHARS, "{%d}", HeapTupleHeaderGetXmax(tuple->t_data));
+
+				values[i] = palloc(NCHARS*sizeof(char));
+				snprintf(values[i++], NCHARS, "{%d}", BackendXidGetPid(HeapTupleHeaderGetXmax(tuple->t_data)));
+			}
+
+#else
+			values[i++] = pstrdup("false");
+			values[i++] = pstrdup("{}");
+			values[i++] = pstrdup("{}");
+#endif
+
+			LockBuffer(scan->rs_cbuf, BUFFER_LOCK_UNLOCK);
+
+			/* 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);
+}

contrib/pgrowlocks/pgrowlocks.sql.in

+-- 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;