Add SHARE UPDATE EXCLUSIVE lock mode, coming soon to a VACUUM near you.

Name chosen per pghackers discussion around 6/22/01.

Add SHARE UPDATE EXCLUSIVE lock mode, coming soon to a VACUUM near you.
Name chosen per pghackers discussion around 6/22/01.
4fe42dfb · Tom Lane · 8902f49a · 4fe42dfb · 4fe42dfb · 4fe42dfb
Commit 4fe42dfb authored Jul 09, 2001 by Tom Lane
8 changed files
--- a/doc/src/sgml/mvcc.sgml
+++ b/doc/src/sgml/mvcc.sgml
 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/mvcc.sgml,v 2.15 2001/05/17 21:50:16 petere Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/mvcc.sgml,v 2.16 2001/07/09 22:18:33 tgl Exp $
 -->

 <chapter id="mvcc">
@@ -441,6 +441,25 @@ ERROR:  Can't serialize access due to concurrent update
       </listitem>
      </varlistentry>

+      <varlistentry>
+       <term>
+	ShareUpdateExclusiveLock
+       </term>
+       <listitem>
+	<para>
+	 Acquired by <command>VACUUM</command> (without <option>FULL</option>)
+	 and <command>LOCK TABLE</command> table
+	 for <option>IN SHARE UPDATE EXCLUSIVE MODE</option>
+	 statements.
+	</para>
+
+	<para>
+	 Conflicts with ShareUpdateExclusiveLock, ShareLock,
+	 ShareRowExclusiveLock, ExclusiveLock and AccessExclusiveLock modes.
+	</para>
+       </listitem>
+      </varlistentry>
+
      <varlistentry>
       <term>
 	ShareLock
@@ -454,7 +473,8 @@ ERROR:  Can't serialize access due to concurrent update
 	</para>

 	<para>
-	 Conflicts with RowExclusiveLock, ShareRowExclusiveLock,
+	 Conflicts with RowExclusiveLock, ShareUpdateExclusiveLock,
+	 ShareRowExclusiveLock,
 	 ExclusiveLock and AccessExclusiveLock modes.
 	</para>
       </listitem>
@@ -471,7 +491,8 @@ ERROR:  Can't serialize access due to concurrent update
 	</para>

 	<para>
-	 Conflicts with RowExclusiveLock, ShareLock, ShareRowExclusiveLock,
+	 Conflicts with RowExclusiveLock, ShareUpdateExclusiveLock,
+	 ShareLock, ShareRowExclusiveLock,
 	 ExclusiveLock and AccessExclusiveLock modes.
 	</para>
       </listitem>
@@ -488,7 +509,8 @@ ERROR:  Can't serialize access due to concurrent update
 	</para>

 	<para>
-	 Conflicts with RowShareLock, RowExclusiveLock, ShareLock,
+	 Conflicts with RowShareLock, RowExclusiveLock,
+	 ShareUpdateExclusiveLock, ShareLock,
 	 ShareRowExclusiveLock, ExclusiveLock and AccessExclusiveLock
 	 modes.
 	</para>
@@ -503,13 +525,13 @@ ERROR:  Can't serialize access due to concurrent update
 	<para>
 	 Acquired by <command>ALTER TABLE</command>,
 	 <command>DROP TABLE</command>,
-	 <command>VACUUM</command> and <command>LOCK TABLE</command>
+	 <command>VACUUM FULL</command> and <command>LOCK TABLE</command>
 	 statements.
 	</para>

 	<para>
 	 Conflicts with all modes (AccessShareLock, RowShareLock,
-	 RowExclusiveLock, ShareLock,
+	 RowExclusiveLock, ShareUpdateExclusiveLock, ShareLock,
 	 ShareRowExclusiveLock, ExclusiveLock and AccessExclusiveLock).
 	</para>
       </listitem>

--- a/doc/src/sgml/ref/lock.sgml
+++ b/doc/src/sgml/ref/lock.sgml
 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/ref/lock.sgml,v 1.23 2000/12/25 23:15:26 petere Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/ref/lock.sgml,v 1.24 2001/07/09 22:18:33 tgl Exp $
 Postgres documentation
 -->

@@ -20,12 +20,16 @@ Postgres documentation
 </refnamediv>
 <refsynopsisdiv>
  <refsynopsisdivinfo>
-   <date>1999-07-20</date>
+   <date>2001-07-09</date>
  </refsynopsisdivinfo>
  <synopsis>
 LOCK [ TABLE ] <replaceable class="PARAMETER">name</replaceable>
-LOCK [ TABLE ] <replaceable class="PARAMETER">name</replaceable> IN [ ROW | ACCESS ] { SHARE | EXCLUSIVE } MODE
-LOCK [ TABLE ] <replaceable class="PARAMETER">name</replaceable> IN SHARE ROW EXCLUSIVE MODE
+LOCK [ TABLE ] <replaceable class="PARAMETER">name</replaceable> IN <replaceable class="PARAMETER">lockmode</replaceable> MODE
+
+where <replaceable class="PARAMETER">lockmode</replaceable> is one of:
+
+	ACCESS SHARE | ROW SHARE | ROW EXCLUSIVE | SHARE UPDATE EXCLUSIVE |
+	SHARE | SHARE ROW EXCLUSIVE | EXCLUSIVE | ACCESS EXCLUSIVE
  </synopsis>

  <refsect2 id="R2-SQL-LOCK-1">
@@ -33,7 +37,6 @@ LOCK [ TABLE ] <replaceable class="PARAMETER">name</replaceable> IN SHARE ROW EX
    <date>1999-06-09</date>
   </refsect2info>

-
   <title>
    Inputs
   </title>
@@ -62,7 +65,7 @@ LOCK [ TABLE ] <replaceable class="PARAMETER">name</replaceable> IN SHARE ROW EX
 	This is the least restrictive lock mode.  It conflicts only with
 	ACCESS EXCLUSIVE mode. It is used to protect a table from being
 	modified by concurrent <command>ALTER TABLE</command>, 
-	<command>DROP TABLE</command> and <command>VACUUM</command> 
+	<command>DROP TABLE</command> and <command>VACUUM FULL</command>
 	commands.
       </para>
      </listitem>
@@ -102,6 +105,25 @@ LOCK [ TABLE ] <replaceable class="PARAMETER">name</replaceable> IN SHARE ROW EX
      </listitem>
     </varlistentry>

+     <varlistentry>
+      <term>SHARE UPDATE EXCLUSIVE MODE</term>
+      <listitem>
+       <note>
+       <para>
+	 Automatically acquired by <command>VACUUM</command> (without
+	 <option>FULL</option>).
+       </para>
+       </note>
+
+       <para>
+	Conflicts with SHARE UPDATE EXCLUSIVE, SHARE, SHARE ROW EXCLUSIVE,
+	EXCLUSIVE and
+	ACCESS EXCLUSIVE modes. This mode protects a table against
+	concurrent schema changes and VACUUMs.
+       </para>
+      </listitem>
+     </varlistentry>
+
     <varlistentry>
      <term>SHARE MODE</term>
      <listitem>
@@ -113,9 +135,10 @@ LOCK [ TABLE ] <replaceable class="PARAMETER">name</replaceable> IN SHARE ROW EX
       </note>

       <para>
-	Conflicts with ROW EXCLUSIVE, SHARE ROW EXCLUSIVE, EXCLUSIVE and
+	Conflicts with ROW EXCLUSIVE, SHARE UPDATE EXCLUSIVE,
+	SHARE ROW EXCLUSIVE, EXCLUSIVE and
 	ACCESS EXCLUSIVE modes. This mode protects a table against
-	concurrent updates.
+	concurrent data updates.
       </para>
      </listitem>
     </varlistentry>
@@ -125,14 +148,14 @@ LOCK [ TABLE ] <replaceable class="PARAMETER">name</replaceable> IN SHARE ROW EX
      <listitem>
       <note>
       <para>
-	This is like EXCLUSIVE MODE, but allows SHARE ROW locks
+	This is like EXCLUSIVE MODE, but allows ROW SHARE locks
        by others.
       </para>
       </note>

       <para>
-        Conflicts with ROW EXCLUSIVE, SHARE, SHARE ROW EXCLUSIVE,
-	EXCLUSIVE and ACCESS EXCLUSIVE modes.
+        Conflicts with ROW EXCLUSIVE, SHARE UPDATE EXCLUSIVE, SHARE,
+	SHARE ROW EXCLUSIVE, EXCLUSIVE and ACCESS EXCLUSIVE modes.
       </para>
      </listitem>
     </varlistentry>
@@ -149,7 +172,8 @@ LOCK [ TABLE ] <replaceable class="PARAMETER">name</replaceable> IN SHARE ROW EX
       </note>

       <para>
-	Conflicts with ROW SHARE, ROW EXCLUSIVE, SHARE, SHARE ROW EXCLUSIVE,
+	Conflicts with ROW SHARE, ROW EXCLUSIVE, SHARE UPDATE EXCLUSIVE,
+	SHARE, SHARE ROW EXCLUSIVE,
 	EXCLUSIVE and ACCESS EXCLUSIVE modes.
       </para>
      </listitem>
@@ -161,9 +185,10 @@ LOCK [ TABLE ] <replaceable class="PARAMETER">name</replaceable> IN SHARE ROW EX
       <note>
 	<para>
 	 Automatically acquired by <command>ALTER TABLE</command>,
-	 <command>DROP TABLE</command>, <command>VACUUM</command> statements.
-	 This is the most restrictive lock mode which conflicts with all other
-	 lock modes and protects a locked table from any concurrent operations.
+	 <command>DROP TABLE</command>, <command>VACUUM FULL</command>
+	 statements.
+	 This is the most restrictive lock mode which
+	 protects a locked table from any concurrent operations.
 	</para>
       </note>

@@ -174,6 +199,10 @@ LOCK [ TABLE ] <replaceable class="PARAMETER">name</replaceable> IN SHARE ROW EX
 	 lock mode option).
 	</para>
       </note>
+
+       <para>
+	Conflicts with all lock modes.
+       </para>
      </listitem>
     </varlistentry>
    </variablelist>
@@ -241,7 +270,11 @@ ERROR <replaceable class="PARAMETER">name</replaceable>: Table does not exist.
     <term>EXCLUSIVE</term>
     <listitem>
      <para>
-       Exclusive lock that prevents other locks from being granted.
+       An exclusive lock prevents other locks of the same type from being
+       granted.  (Note: ROW EXCLUSIVE mode does not follow this naming
+       convention perfectly, since it is shared at the level of the table;
+       it is exclusive only with respect to specific rows that are being
+       updated.)
      </para>
     </listitem>
    </varlistentry>
@@ -250,7 +283,8 @@ ERROR <replaceable class="PARAMETER">name</replaceable>: Table does not exist.
     <term>SHARE</term>
     <listitem>
      <para>
-       Allows others to share lock.  Prevents EXCLUSIVE locks.
+      A shared lock allows others to also hold the same type of lock,
+      but prevents the corresponding EXCLUSIVE lock from being granted.
      </para>
     </listitem>
    </varlistentry>
@@ -273,13 +307,6 @@ ERROR <replaceable class="PARAMETER">name</replaceable>: Table does not exist.
     </listitem>
    </varlistentry>
   </variablelist>
-
-   <note>
-    <para>
-     If EXCLUSIVE or SHARE are not specified, EXCLUSIVE is assumed.
-     Locks exist for the duration of the transaction.
-    </para>
-   </note>
  </para>

  <para>
@@ -370,8 +397,8 @@ ERROR <replaceable class="PARAMETER">name</replaceable>: Table does not exist.
   </para>

   <para>
-    Except for ACCESS SHARE/EXCLUSIVE lock modes, all other
-    <productname>Postgres</productname> lock modes and the
+    Except for ACCESS SHARE, ACCESS EXCLUSIVE, and SHARE UPDATE EXCLUSIVE lock
+    modes, the <productname>Postgres</productname> lock modes and the
    <command>LOCK TABLE</command> syntax are compatible with those
    present in <productname>Oracle</productname>.
   </para>

--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -11,7 +11,7 @@
 *
 *
 * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.233 2001/06/30 22:03:25 petere Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.234 2001/07/09 22:18:33 tgl Exp $
 *
 * HISTORY
 *	  AUTHOR			DATE			MAJOR EVENT
@@ -153,7 +153,7 @@ static void doNegateFloat(Value *v);
 %type <list>	createdb_opt_list, createdb_opt_item

 %type <ival>	opt_lock, lock_type
-%type <boolean>	opt_lmode, opt_force
+%type <boolean>	opt_force

 %type <ival>    user_createdb_clause, user_createuser_clause
 %type <str>		user_passwd_clause
@@ -3277,18 +3277,18 @@ LockStmt:	LOCK_P opt_table relation_name opt_lock
 				}
 		;

-opt_lock:  IN lock_type MODE		{ $$ = $2; }
+opt_lock:  IN lock_type MODE	{ $$ = $2; }
 		| /*EMPTY*/				{ $$ = AccessExclusiveLock; }
 		;

-lock_type:  SHARE ROW EXCLUSIVE	{ $$ = ShareRowExclusiveLock; }
-		| ROW opt_lmode			{ $$ = ($2? RowShareLock: RowExclusiveLock); }
-		| ACCESS opt_lmode		{ $$ = ($2? AccessShareLock: AccessExclusiveLock); }
-		| opt_lmode				{ $$ = ($1? ShareLock: ExclusiveLock); }
-		;
-
-opt_lmode:	SHARE				{ $$ = TRUE; }
-		| EXCLUSIVE				{ $$ = FALSE; }
+lock_type:  ACCESS SHARE		{ $$ = AccessShareLock; }
+		| ROW SHARE				{ $$ = RowShareLock; }
+		| ROW EXCLUSIVE			{ $$ = RowExclusiveLock; }
+		| SHARE UPDATE EXCLUSIVE { $$ = ShareUpdateExclusiveLock; }
+		| SHARE					{ $$ = ShareLock; }
+		| SHARE ROW EXCLUSIVE	{ $$ = ShareRowExclusiveLock; }
+		| EXCLUSIVE				{ $$ = ExclusiveLock; }
+		| ACCESS EXCLUSIVE		{ $$ = AccessExclusiveLock; }
 		;



--- a/src/backend/storage/lmgr/lmgr.c
+++ b/src/backend/storage/lmgr/lmgr.c
@@ -8,7 +8,7 @@
 *
 *
 * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lmgr.c,v 1.48 2001/06/22 00:04:59 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lmgr.c,v 1.49 2001/07/09 22:18:33 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
@@ -33,25 +33,35 @@ static LOCKMASK LockConflicts[] = {
 	(1 << ExclusiveLock) | (1 << AccessExclusiveLock),

 	/* RowExclusiveLock */
-	(1 << ExclusiveLock) | (1 << ShareRowExclusiveLock) | (1 << ShareLock) |
-	(1 << AccessExclusiveLock),
+	(1 << ShareLock) | (1 << ShareRowExclusiveLock) |
+	(1 << ExclusiveLock) | (1 << AccessExclusiveLock),
+
+	/* ShareUpdateExclusiveLock */
+	(1 << ShareUpdateExclusiveLock) |
+	(1 << ShareLock) | (1 << ShareRowExclusiveLock) |
+	(1 << ExclusiveLock) | (1 << AccessExclusiveLock),

 	/* ShareLock */
-	(1 << ExclusiveLock) | (1 << ShareRowExclusiveLock) |
-	(1 << RowExclusiveLock) | (1 << AccessExclusiveLock),
+	(1 << RowExclusiveLock) | (1 << ShareUpdateExclusiveLock) |
+	(1 << ShareRowExclusiveLock) |
+	(1 << ExclusiveLock) | (1 << AccessExclusiveLock),

 	/* ShareRowExclusiveLock */
-	(1 << ExclusiveLock) | (1 << ShareRowExclusiveLock) |
-	(1 << ShareLock) | (1 << RowExclusiveLock) | (1 << AccessExclusiveLock),
+	(1 << RowExclusiveLock) | (1 << ShareUpdateExclusiveLock) |
+	(1 << ShareLock) | (1 << ShareRowExclusiveLock) |
+	(1 << ExclusiveLock) | (1 << AccessExclusiveLock),

 	/* ExclusiveLock */
-	(1 << ExclusiveLock) | (1 << ShareRowExclusiveLock) | (1 << ShareLock) |
-	(1 << RowExclusiveLock) | (1 << RowShareLock) | (1 << AccessExclusiveLock),
+	(1 << RowShareLock) |
+	(1 << RowExclusiveLock) | (1 << ShareUpdateExclusiveLock) |
+	(1 << ShareLock) | (1 << ShareRowExclusiveLock) |
+	(1 << ExclusiveLock) | (1 << AccessExclusiveLock),

 	/* AccessExclusiveLock */
-	(1 << ExclusiveLock) | (1 << ShareRowExclusiveLock) | (1 << ShareLock) |
-	(1 << RowExclusiveLock) | (1 << RowShareLock) |
-	(1 << AccessExclusiveLock) | (1 << AccessShareLock)
+	(1 << AccessShareLock) | (1 << RowShareLock) |
+	(1 << RowExclusiveLock) | (1 << ShareUpdateExclusiveLock) |
+	(1 << ShareLock) | (1 << ShareRowExclusiveLock) |
+	(1 << ExclusiveLock) | (1 << AccessExclusiveLock)

 };

@@ -63,14 +73,16 @@ static int	LockPrios[] = {
 	2,
 	/* RowExclusiveLock */
 	3,
-	/* ShareLock */
+	/* ShareUpdateExclusiveLock */
 	4,
-	/* ShareRowExclusiveLock */
+	/* ShareLock */
 	5,
-	/* ExclusiveLock */
+	/* ShareRowExclusiveLock */
 	6,
+	/* ExclusiveLock */
+	7,
 	/* AccessExclusiveLock */
-	7
+	8
 };

 LOCKMETHOD	LockTableId = (LOCKMETHOD) NULL;

--- a/src/backend/storage/lmgr/lock.c
+++ b/src/backend/storage/lmgr/lock.c
@@ -8,7 +8,7 @@
 *
 *
 * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lock.c,v 1.90 2001/06/27 23:31:39 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lock.c,v 1.91 2001/07/09 22:18:33 tgl Exp $
 *
 * NOTES
 *	  Outside modules can create a lock table and acquire/release
@@ -58,6 +58,7 @@ static char *lock_mode_names[] =
 	"AccessShareLock",
 	"RowShareLock",
 	"RowExclusiveLock",
+	"ShareUpdateExclusiveLock",
 	"ShareLock",
 	"ShareRowExclusiveLock",
 	"ExclusiveLock",

--- a/src/include/storage/lmgr.h
+++ b/src/include/storage/lmgr.h
@@ -7,7 +7,7 @@
 * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
- * $Id: lmgr.h,v 1.31 2001/06/22 00:04:59 tgl Exp $
+ * $Id: lmgr.h,v 1.32 2001/07/09 22:18:34 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
@@ -25,13 +25,14 @@
 #define AccessShareLock			1		/* SELECT */
 #define RowShareLock			2		/* SELECT FOR UPDATE */
 #define RowExclusiveLock		3		/* INSERT, UPDATE, DELETE */
-#define ShareLock				4		/* CREATE INDEX */
-#define ShareRowExclusiveLock	5		/* like EXCLUSIVE MODE, allows
-										 * SHARE ROW */
-#define ExclusiveLock			6		/* blocks ROW SHARE/SELECT...FOR
+#define ShareUpdateExclusiveLock 4		/* VACUUM (non-FULL) */
+#define ShareLock				5		/* CREATE INDEX */
+#define ShareRowExclusiveLock	6		/* like EXCLUSIVE MODE, but allows
+										 * ROW SHARE */
+#define ExclusiveLock			7		/* blocks ROW SHARE/SELECT...FOR
 										 * UPDATE */
-#define AccessExclusiveLock		7		/* ALTER TABLE, DROP TABLE,
-										 * VACUUM, and unqualified LOCK
+#define AccessExclusiveLock		8		/* ALTER TABLE, DROP TABLE,
+										 * VACUUM FULL, and unqualified LOCK
 										 * TABLE */

 /*

--- a/src/include/storage/lock.h
+++ b/src/include/storage/lock.h
@@ -7,7 +7,7 @@
 * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
- * $Id: lock.h,v 1.50 2001/06/27 23:31:39 tgl Exp $
+ * $Id: lock.h,v 1.51 2001/07/09 22:18:34 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
@@ -49,7 +49,7 @@ typedef int LOCKMODE;
 typedef int LOCKMETHOD;

 /* MAX_LOCKMODES cannot be larger than the # of bits in LOCKMASK */
-#define MAX_LOCKMODES		8
+#define MAX_LOCKMODES		10

 /*
 * MAX_LOCK_METHODS corresponds to the number of spin locks allocated in
@@ -91,7 +91,7 @@ typedef int LOCKMETHOD;
 *
 * prio -- each lockmode has a priority, so, for example, waiting
 *		writers can be given priority over readers (to avoid
- *		starvation).
+ *		starvation).  XXX this field is not actually used at present!
 *
 * masterlock -- synchronizes access to the table
 */

--- a/src/interfaces/ecpg/preproc/preproc.y
+++ b/src/interfaces/ecpg/preproc/preproc.y
@@ -326,7 +326,7 @@ make_name(void)
 %type  <str>	createdb_opt_list opt_encoding OptInherit Geometric
 %type  <str>    DropdbStmt ClusterStmt grantee RevokeStmt Bit bit
 %type  <str>	GrantStmt privileges operation_commalist operation PosAllConst
-%type  <str>	opt_cursor opt_lmode ConstraintsSetStmt comment_tg AllConst
+%type  <str>	opt_cursor ConstraintsSetStmt comment_tg AllConst
 %type  <str>	case_expr when_clause_list case_default case_arg when_clause
 %type  <str>    select_clause opt_select_limit select_limit_value ConstraintTimeSpec
 %type  <str>    select_offset_value ReindexStmt join_type opt_boolean
@@ -2440,15 +2440,15 @@ opt_lock:  IN lock_type MODE            { $$ = cat_str(3, make_str("in"), $2, ma
                | /*EMPTY*/             { $$ = EMPTY;}
                ;

-lock_type:  SHARE ROW EXCLUSIVE 	{ $$ = make_str("share row exclusive"); }
-                | ROW opt_lmode         { $$ = cat2_str(make_str("row"), $2);}
-                | ACCESS opt_lmode      { $$ = cat2_str(make_str("access"), $2);}
-                | opt_lmode             { $$ = $1; }
-                ;
-
-opt_lmode:      SHARE                           { $$ = make_str("share"); }
-                | EXCLUSIVE                     { $$ = make_str("exclusive"); }
-                ;
+lock_type:  ACCESS SHARE		{ $$ = make_str("access share"); }
+		| ROW SHARE				{ $$ = make_str("access share"); }
+		| ROW EXCLUSIVE			{ $$ = make_str("row exclusive"); }
+		| SHARE UPDATE EXCLUSIVE { $$ = make_str("share update exclusive"); }
+		| SHARE					{ $$ = make_str("share"); }
+		| SHARE ROW EXCLUSIVE	{ $$ = make_str("share row exclusive"); }
+		| EXCLUSIVE				{ $$ = make_str("exclusive"); }
+		| ACCESS EXCLUSIVE		{ $$ = make_str("access exclusive"); }
+		;

 /*****************************************************************************
 *