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Extend the pg_locks system view so that it can fully display all lock
types, as per recent discussion.
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7 files changed

+204
-49
lines changed

7 files changed

+204
-49
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‎contrib/userlock/user_locks.c‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -19,9 +19,9 @@
1919

2020

2121
#define SET_LOCKTAG_USERLOCK(locktag,id1,id2) \
22-
((locktag).locktag_field1 = (id1), \
23-
(locktag).locktag_field2 = (id2), \
24-
(locktag).locktag_field3 = MyDatabaseId, \
22+
((locktag).locktag_field1 = MyDatabaseId, \
23+
(locktag).locktag_field2 = (id1), \
24+
(locktag).locktag_field3 = (id2), \
2525
(locktag).locktag_field4 = 0, \
2626
(locktag).locktag_type = LOCKTAG_USERLOCK)
2727

‎doc/src/sgml/catalogs.sgml‎

Lines changed: 96 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,6 @@
11
<!--
22
Documentation of the system catalogs, directed toward PostgreSQL developers
3-
$PostgreSQL: pgsql/doc/src/sgml/catalogs.sgml,v 2.101 2005/05/06 14:28:53 tgl Exp $
3+
$PostgreSQL: pgsql/doc/src/sgml/catalogs.sgml,v 2.102 2005/05/17 21:46:09 tgl Exp $
44
-->
55

66
<chapter id="catalogs">
@@ -4040,15 +4040,18 @@
40404040
lockable object may
40414041
appear many times, if multiple transactions are holding or waiting
40424042
for locks on it. However, an object that currently has no locks on it
4043-
will not appear at all. A lockable object is either a relation (e.g., a
4044-
table) or a transaction ID.
4043+
will not appear at all.
40454044
</para>
40464045

40474046
<para>
4048-
Note that this view includes only table-level
4049-
locks, not row-level ones. If a transaction is waiting for a
4050-
row-level lock, it will appear in the view as waiting for the
4051-
transaction ID of the current holder of that row lock.
4047+
There are several distinct types of lockable objects:
4048+
whole relations (e.g., tables), individual pages of relations,
4049+
individual tuples of relations,
4050+
transaction IDs,
4051+
and general database objects (identified by class OID and object OID,
4052+
in the same way as in <structname>pg_description</structname> or
4053+
<structname>pg_depend</structname>). Also, the right to extend a
4054+
relation is represented as a separate lockable object.
40524055
</para>
40534056

40544057
<table>
@@ -4065,37 +4068,98 @@
40654068
</thead>
40664069
<tbody>
40674070
<row>
4068-
<entry><structfield>relation</structfield></entry>
4069-
<entry><type>oid</type></entry>
4070-
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
4071+
<entry><structfield>locktype</structfield></entry>
4072+
<entry><type>text</type></entry>
4073+
<entry></entry>
40714074
<entry>
4072-
OID of the locked relation, or NULL if the lockable object
4073-
is a transaction ID
4075+
type of the lockable object:
4076+
<literal>relation</>,
4077+
<literal>extend</>,
4078+
<literal>page</>,
4079+
<literal>tuple</>,
4080+
<literal>transaction</>,
4081+
<literal>object</>, or
4082+
<literal>userlock</>
40744083
</entry>
40754084
</row>
40764085
<row>
40774086
<entry><structfield>database</structfield></entry>
40784087
<entry><type>oid</type></entry>
40794088
<entry><literal><link linkend="catalog-pg-database"><structname>pg_database</structname></link>.oid</literal></entry>
40804089
<entry>
4081-
OID of the database in which the locked relation exists, or
4082-
zero if the locked relation is a globally-shared table, or
4083-
NULL if the lockable object is a transaction ID
4090+
OID of the database in which the object exists, or
4091+
zero if the object is a globally-shared object, or
4092+
NULL if the object is a transaction ID
4093+
</entry>
4094+
</row>
4095+
<row>
4096+
<entry><structfield>relation</structfield></entry>
4097+
<entry><type>oid</type></entry>
4098+
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
4099+
<entry>
4100+
OID of the relation, or NULL if the object is not
4101+
a relation or part of a relation
4102+
</entry>
4103+
</row>
4104+
<row>
4105+
<entry><structfield>page</structfield></entry>
4106+
<entry><type>integer</type></entry>
4107+
<entry></entry>
4108+
<entry>
4109+
page number within the relation, or NULL if the object
4110+
is not a tuple or relation page
4111+
</entry>
4112+
</row>
4113+
<row>
4114+
<entry><structfield>tuple</structfield></entry>
4115+
<entry><type>smallint</type></entry>
4116+
<entry></entry>
4117+
<entry>
4118+
tuple number within the page, or NULL if the object is not a tuple
40844119
</entry>
40854120
</row>
40864121
<row>
40874122
<entry><structfield>transaction</structfield></entry>
40884123
<entry><type>xid</type></entry>
40894124
<entry></entry>
40904125
<entry>
4091-
ID of a transaction, or NULL if the lockable object is a relation
4126+
ID of a transaction, or NULL if the object is not a transaction ID
4127+
</entry>
4128+
</row>
4129+
<row>
4130+
<entry><structfield>classid</structfield></entry>
4131+
<entry><type>oid</type></entry>
4132+
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
4133+
<entry>
4134+
OID of the system catalog containing the object, or NULL if the
4135+
object is not a general database object
4136+
</entry>
4137+
</row>
4138+
<row>
4139+
<entry><structfield>objid</structfield></entry>
4140+
<entry><type>oid</type></entry>
4141+
<entry>any OID column</entry>
4142+
<entry>
4143+
OID of the object within its system catalog, or NULL if the
4144+
object is not a general database object
4145+
</entry>
4146+
</row>
4147+
<row>
4148+
<entry><structfield>objsubid</structfield></entry>
4149+
<entry><type>smallint</type></entry>
4150+
<entry></entry>
4151+
<entry>
4152+
For a table column, this is the column number (the
4153+
<structfield>classid</> and <structfield>objid</> refer to the
4154+
table itself). For all other object types, this column is
4155+
zero. NULL if the object is not a general database object
40924156
</entry>
40934157
</row>
40944158
<row>
40954159
<entry><structfield>pid</structfield></entry>
40964160
<entry><type>integer</type></entry>
40974161
<entry></entry>
4098-
<entry>process ID of a server process holding or awaiting this
4162+
<entry>process ID of the server process holding or awaiting this
40994163
lock</entry>
41004164
</row>
41014165
<row>
@@ -4133,6 +4197,21 @@
41334197
terminates and releases its locks.
41344198
</para>
41354199

4200+
<para>
4201+
Although tuples are a lockable type of object,
4202+
information about row-level locks is stored on disk, not in memory,
4203+
and therefore row-level locks normally do not appear in this view.
4204+
If a transaction is waiting for a
4205+
row-level lock, it will usually appear in the view as waiting for the
4206+
transaction ID of the current holder of that row lock.
4207+
</para>
4208+
4209+
<para>
4210+
If user-defined locks are in use, they are displayed using the columns
4211+
for general database objects. However, the actual meaning of the lock
4212+
fields in such cases is up to the user.
4213+
</para>
4214+
41364215
<para>
41374216
When the <structname>pg_locks</structname> view is accessed, the
41384217
internal lock manager data structures are momentarily locked, and

‎src/backend/catalog/system_views.sql‎

Lines changed: 5 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -3,7 +3,7 @@
33
*
44
* Copyright (c) 1996-2005, PostgreSQL Global Development Group
55
*
6-
* $PostgreSQL: pgsql/src/backend/catalog/system_views.sql,v 1.12 2005/05/09 11:31:32 neilc Exp $
6+
* $PostgreSQL: pgsql/src/backend/catalog/system_views.sql,v 1.13 2005/05/17 21:46:09 tgl Exp $
77
*/
88

99
CREATE VIEW pg_user AS
@@ -261,8 +261,10 @@ CREATE VIEW pg_stat_database AS
261261

262262
CREATE VIEW pg_locks AS
263263
SELECT *
264-
FROM pg_lock_status() AS L(relation oid, database oid,
265-
transaction xid, pid int4, mode text, granted boolean);
264+
FROM pg_lock_status() AS L
265+
(locktype text, database oid, relation oid, page int4, tuple int2,
266+
transaction xid, classid oid, objid oid, objsubid int2,
267+
pid int4, mode text, granted boolean);
266268

267269
CREATE VIEW pg_settings AS
268270
SELECT *

‎src/backend/utils/adt/lockfuncs.c‎

Lines changed: 95 additions & 21 deletions
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
* Copyright (c) 2002-2005, PostgreSQL Global Development Group
77
*
88
* IDENTIFICATION
9-
* $PostgreSQL: pgsql/src/backend/utils/adt/lockfuncs.c,v 1.17 2005/04/29 22:28:24 tgl Exp $
9+
* $PostgreSQL: pgsql/src/backend/utils/adt/lockfuncs.c,v 1.18 2005/05/17 21:46:10 tgl Exp $
1010
*
1111
*-------------------------------------------------------------------------
1212
*/
@@ -20,6 +20,17 @@
2020
#include "utils/builtins.h"
2121

2222

23+
/* This must match enum LockTagType! */
24+
static const char * const LockTagTypeNames[] = {
25+
"relation",
26+
"extend",
27+
"page",
28+
"tuple",
29+
"transaction",
30+
"object",
31+
"userlock"
32+
};
33+
2334
/* Working status for pg_lock_status */
2435
typedef struct
2536
{
@@ -53,18 +64,30 @@ pg_lock_status(PG_FUNCTION_ARGS)
5364

5465
/* build tupdesc for result tuples */
5566
/* this had better match pg_locks view in system_views.sql */
56-
tupdesc = CreateTemplateTupleDesc(6, false);
57-
TupleDescInitEntry(tupdesc, (AttrNumber) 1, "relation",
58-
OIDOID, -1, 0);
67+
tupdesc = CreateTemplateTupleDesc(12, false);
68+
TupleDescInitEntry(tupdesc, (AttrNumber) 1, "locktype",
69+
TEXTOID, -1, 0);
5970
TupleDescInitEntry(tupdesc, (AttrNumber) 2, "database",
6071
OIDOID, -1, 0);
61-
TupleDescInitEntry(tupdesc, (AttrNumber) 3, "transaction",
72+
TupleDescInitEntry(tupdesc, (AttrNumber) 3, "relation",
73+
OIDOID, -1, 0);
74+
TupleDescInitEntry(tupdesc, (AttrNumber) 4, "page",
75+
INT4OID, -1, 0);
76+
TupleDescInitEntry(tupdesc, (AttrNumber) 5, "tuple",
77+
INT2OID, -1, 0);
78+
TupleDescInitEntry(tupdesc, (AttrNumber) 6, "transaction",
6279
XIDOID, -1, 0);
63-
TupleDescInitEntry(tupdesc, (AttrNumber) 4, "pid",
80+
TupleDescInitEntry(tupdesc, (AttrNumber) 7, "classid",
81+
OIDOID, -1, 0);
82+
TupleDescInitEntry(tupdesc, (AttrNumber) 8, "objid",
83+
OIDOID, -1, 0);
84+
TupleDescInitEntry(tupdesc, (AttrNumber) 9, "objsubid",
85+
INT2OID, -1, 0);
86+
TupleDescInitEntry(tupdesc, (AttrNumber) 10, "pid",
6487
INT4OID, -1, 0);
65-
TupleDescInitEntry(tupdesc, (AttrNumber) 5, "mode",
88+
TupleDescInitEntry(tupdesc, (AttrNumber) 11, "mode",
6689
TEXTOID, -1, 0);
67-
TupleDescInitEntry(tupdesc, (AttrNumber) 6, "granted",
90+
TupleDescInitEntry(tupdesc, (AttrNumber) 12, "granted",
6891
BOOLOID, -1, 0);
6992

7093
funcctx->tuple_desc = BlessTupleDesc(tupdesc);
@@ -93,8 +116,10 @@ pg_lock_status(PG_FUNCTION_ARGS)
93116
PGPROC *proc;
94117
bool granted;
95118
LOCKMODE mode = 0;
96-
Datum values[6];
97-
char nulls[6];
119+
const char *locktypename;
120+
char tnbuf[32];
121+
Datum values[12];
122+
char nulls[12];
98123
HeapTuple tuple;
99124
Datum result;
100125

@@ -155,30 +180,79 @@ pg_lock_status(PG_FUNCTION_ARGS)
155180
MemSet(values, 0, sizeof(values));
156181
MemSet(nulls, ' ', sizeof(nulls));
157182

183+
if (lock->tag.locktag_type <= LOCKTAG_USERLOCK)
184+
locktypename = LockTagTypeNames[lock->tag.locktag_type];
185+
else
186+
{
187+
snprintf(tnbuf, sizeof(tnbuf), "unknown %d",
188+
(int) lock->tag.locktag_type);
189+
locktypename = tnbuf;
190+
}
191+
values[0] = DirectFunctionCall1(textin,
192+
CStringGetDatum(locktypename));
193+
194+
158195
switch (lock->tag.locktag_type)
159196
{
160197
case LOCKTAG_RELATION:
161198
case LOCKTAG_RELATION_EXTEND:
199+
values[1] = ObjectIdGetDatum(lock->tag.locktag_field1);
200+
values[2] = ObjectIdGetDatum(lock->tag.locktag_field2);
201+
nulls[3] = 'n';
202+
nulls[4] = 'n';
203+
nulls[5] = 'n';
204+
nulls[6] = 'n';
205+
nulls[7] = 'n';
206+
nulls[8] = 'n';
207+
break;
162208
case LOCKTAG_PAGE:
209+
values[1] = ObjectIdGetDatum(lock->tag.locktag_field1);
210+
values[2] = ObjectIdGetDatum(lock->tag.locktag_field2);
211+
values[3] = UInt32GetDatum(lock->tag.locktag_field3);
212+
nulls[4] = 'n';
213+
nulls[5] = 'n';
214+
nulls[6] = 'n';
215+
nulls[7] = 'n';
216+
nulls[8] = 'n';
217+
break;
163218
case LOCKTAG_TUPLE:
164-
values[0] = ObjectIdGetDatum(lock->tag.locktag_field2);
165219
values[1] = ObjectIdGetDatum(lock->tag.locktag_field1);
166-
nulls[2] = 'n';
220+
values[2] = ObjectIdGetDatum(lock->tag.locktag_field2);
221+
values[3] = UInt32GetDatum(lock->tag.locktag_field3);
222+
values[4] = UInt16GetDatum(lock->tag.locktag_field4);
223+
nulls[5] = 'n';
224+
nulls[6] = 'n';
225+
nulls[7] = 'n';
226+
nulls[8] = 'n';
167227
break;
168228
case LOCKTAG_TRANSACTION:
169-
nulls[0] = 'n';
229+
values[5] = TransactionIdGetDatum(lock->tag.locktag_field1);
170230
nulls[1] = 'n';
171-
values[2] = TransactionIdGetDatum(lock->tag.locktag_field1);
231+
nulls[2] = 'n';
232+
nulls[3] = 'n';
233+
nulls[4] = 'n';
234+
nulls[6] = 'n';
235+
nulls[7] = 'n';
236+
nulls[8] = 'n';
237+
break;
238+
case LOCKTAG_OBJECT:
239+
case LOCKTAG_USERLOCK:
240+
default: /* treat unknown locktags like OBJECT */
241+
values[1] = ObjectIdGetDatum(lock->tag.locktag_field1);
242+
values[6] = ObjectIdGetDatum(lock->tag.locktag_field2);
243+
values[7] = ObjectIdGetDatum(lock->tag.locktag_field3);
244+
values[8] = Int16GetDatum(lock->tag.locktag_field4);
245+
nulls[2] = 'n';
246+
nulls[3] = 'n';
247+
nulls[4] = 'n';
248+
nulls[5] = 'n';
172249
break;
173-
default:
174-
/* XXX Ignore all other lock types for now */
175-
continue;
176250
}
177251

178-
values[3] = Int32GetDatum(proc->pid);
179-
values[4] = DirectFunctionCall1(textin,
180-
CStringGetDatum(GetLockmodeName(mode)));
181-
values[5] = BoolGetDatum(granted);
252+
values[9] = Int32GetDatum(proc->pid);
253+
values[10] = DirectFunctionCall1(textin,
254+
CStringGetDatum(GetLockmodeName(mode)));
255+
values[11] = BoolGetDatum(granted);
182256

183257
tuple = heap_formtuple(funcctx->tuple_desc, values, nulls);
184258
result = HeapTupleGetDatum(tuple);

‎src/include/catalog/catversion.h‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -37,7 +37,7 @@
3737
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
3838
* Portions Copyright (c) 1994, Regents of the University of California
3939
*
40-
* $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.267 2005/05/09 11:31:34 neilc Exp $
40+
* $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.268 2005/05/17 21:46:10 tgl Exp $
4141
*
4242
*-------------------------------------------------------------------------
4343
*/
@@ -53,6 +53,6 @@
5353
*/
5454

5555
/* yyyymmddN */
56-
#define CATALOG_VERSION_NO 200505091
56+
#define CATALOG_VERSION_NO 200505171
5757

5858
#endif

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