-$PostgreSQL: pgsql/contrib/pgrowlocks/README.pgrowlocks,v 1.1 2006/04/23 01:12:58 ishii Exp $
+$PostgreSQL: pgsql/contrib/pgrowlocks/README.pgrowlocks,v 1.2 2007/08/27 00:13:51 tgl Exp $
pgrowlocks README Tatsuo Ishii
pgrowlocks shows row locking information for specified table.
- pgrowlocks returns following data type:
+ pgrowlocks returns following columns:
-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:
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:
/*
- * $PostgreSQL: pgsql/contrib/pgrowlocks/pgrowlocks.c,v 1.5 2006/10/04 00:29:46 momjian Exp $
+ * $PostgreSQL: pgsql/contrib/pgrowlocks/pgrowlocks.c,v 1.6 2007/08/27 00:13:51 tgl Exp $
*
* Copyright (c) 2005-2006 Tatsuo Ishii
*
#include "postgres.h"
-#include "funcapi.h"
#include "access/heapam.h"
-#include "access/transam.h"
+#include "access/multixact.h"
#include "access/xact.h"
#include "catalog/namespace.h"
-#include "catalog/pg_type.h"
-#include "storage/proc.h"
+#include "funcapi.h"
+#include "miscadmin.h"
+#include "storage/procarray.h"
#include "utils/builtins.h"
-#ifdef HEAP_XMAX_SHARED_LOCK
-#include "access/multixact.h"
-#include "storage/procarray.h"
-#endif
PG_MODULE_MAGIC;
/* ----------
* 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
{
Relation rel;
MyData *mydata;
Relation rel;
+ if (!superuser())
+ ereport(ERROR,
+ (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+ (errmsg("must be superuser to use pgrowlocks"))));
+
if (SRF_IS_FIRSTCALL())
{
text *relname;
funcctx = SRF_FIRSTCALL_INIT();
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
- tupdesc = RelationNameGetTupleDesc(DUMMY_TUPLE);
+ /* Build a tuple descriptor for our result type */
+ if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
+ elog(ERROR, "return type must be a row type");
+
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->rel = rel;
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;
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);
-- 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
+CREATE OR REPLACE FUNCTION pgrowlocks(IN relname text,
+ OUT locked_row TID, -- row TID
+ OUT lock_type TEXT, -- lock type
+ OUT locker XID, -- locking XID
+ OUT multi bool, -- multi XID?
+ OUT xids xid[], -- multi XIDs
+ OUT pids INTEGER[]) -- locker's process id
+RETURNS SETOF record
AS 'MODULE_PATHNAME', 'pgrowlocks'
-LANGUAGE 'C' STRICT;
+LANGUAGE C STRICT;