Add a pg_dump option --lock-wait-timeout to allow failing the dump if unable

to acquire shared table locks within a specified amount of time.

David Gould

doc/src/sgml/ref/pg_dump.sgml

@@ -1,5 +1,5 @@
 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/pg_dump.sgml,v 1.102 2008/04/13 03:49:21 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/pg_dump.sgml,v 1.103 2008/07/20 18:43:30 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -415,23 +415,6 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
-     <varlistentry>
-      <term><option>--no-tablespaces</option></term>
-      <listitem>
-       <para>
-        Do not output commands to select tablespaces.
-        With this option, all objects will be created in whichever
-        tablespace is the default during restore.
-       </para>
-
-       <para>
-        This option is only meaningful for the plain-text format.  For
-        the archive formats, you can specify the option when you
-        call <command>pg_restore</command>.
-       </para>
-      </listitem>
-     </varlistentry>
-
      <varlistentry>
       <term><option>-s</option></term>
       <term><option>--schema-only</option></term>
@@ -550,6 +533,18 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-Z <replaceable class="parameter">0..9</replaceable></option></term>
+      <term><option>--compress=<replaceable class="parameter">0..9</replaceable></option></term>
+      <listitem>
+       <para>
+        Specify the compression level to use in archive formats that
+        support compression.  (Currently only the custom archive
+        format supports compression.)
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--disable-dollar-quoting</></term>
       <listitem>
@@ -587,6 +582,39 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>--lock-wait-timeout=<replaceable class="parameter">timeout</replaceable></option></term>
+      <listitem>
+       <para>
+        Do not wait forever to acquire shared table locks at the beginning of
+        the dump. Instead fail if unable to lock a table within the specified
+        <replaceable class="parameter">timeout</>. The timeout may be
+        specified in any of the formats accepted by <command>SET
+        statement_timeout</>.  (Allowed values vary depending on the server
+        version you are dumping from, but an integer number of milliseconds
+        is accepted by all versions since 7.3.  This option is ignored when
+        dumping from a pre-7.3 server.)
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><option>--no-tablespaces</option></term>
+      <listitem>
+       <para>
+        Do not output commands to select tablespaces.
+        With this option, all objects will be created in whichever
+        tablespace is the default during restore.
+       </para>
+
+       <para>
+        This option is only meaningful for the plain-text format.  For
+        the archive formats, you can specify the option when you
+        call <command>pg_restore</command>.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--use-set-session-authorization</></term>
       <listitem>
@@ -601,18 +629,6 @@ PostgreSQL documentation
        </para>
       </listitem>
      </varlistentry>
-
-     <varlistentry>
-      <term><option>-Z <replaceable class="parameter">0..9</replaceable></option></term>
-      <term><option>--compress=<replaceable class="parameter">0..9</replaceable></option></term>
-      <listitem>
-       <para>
-        Specify the compression level to use in archive formats that
-        support compression.  (Currently only the custom archive
-        format supports compression.)
-       </para>
-      </listitem>
-     </varlistentry>
     </variablelist>
    </para>
 

src/bin/pg_dump/pg_dump.c

@@ -12,7 +12,7 @@
  *	by PostgreSQL
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/bin/pg_dump/pg_dump.c,v 1.496 2008/07/18 03:32:52 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/bin/pg_dump/pg_dump.c,v 1.497 2008/07/20 18:43:30 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -71,6 +71,7 @@ bool		attrNames;			/* put attr names into insert strings */
 bool		schemaOnly;
 bool		dataOnly;
 bool		aclsSkip;
+const char *lockWaitTimeout;
 
 /* subquery used to convert user ID (eg, datdba) to user name */
 static const char *username_subquery;
@@ -264,6 +265,7 @@ main(int argc, char **argv)
 		 */
 		{"disable-dollar-quoting", no_argument, &disable_dollar_quoting, 1},
 		{"disable-triggers", no_argument, &disable_triggers, 1},
+		{"lock-wait-timeout", required_argument, NULL, 2},
 		{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
 		{"use-set-session-authorization", no_argument, &use_setsessauth, 1},
 
@@ -279,6 +281,7 @@ main(int argc, char **argv)
 	strcpy(g_opaque_type, "opaque");
 
 	dataOnly = schemaOnly = dumpInserts = attrNames = false;
+	lockWaitTimeout = NULL;
 
 	progname = get_progname(argv[0]);
 
@@ -437,6 +440,11 @@ main(int argc, char **argv)
 				/* This covers the long options equivalent to -X xxx. */
 				break;
 
+			case 2:
+				/* lock-wait-timeout */
+				lockWaitTimeout = optarg;
+				break;
+
 			default:
 				fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
 				exit(1);
@@ -758,6 +766,7 @@ help(const char *progname)
 	printf(_("  -F, --format=c|t|p          output file format (custom, tar, plain text)\n"));
 	printf(_("  -v, --verbose               verbose mode\n"));
 	printf(_("  -Z, --compress=0-9          compression level for compressed formats\n"));
+	printf(_("  --lock-wait-timeout=TIMEOUT fail after waiting TIMEOUT for a table lock\n"));
 	printf(_("  --help                      show this help, then exit\n"));
 	printf(_("  --version                   output version information, then exit\n"));
 
@@ -2957,8 +2966,6 @@ getTables(int *numTables)
 	int			ntups;
 	int			i;
 	PQExpBuffer query = createPQExpBuffer();
-	PQExpBuffer delqry = createPQExpBuffer();
-	PQExpBuffer lockquery = createPQExpBuffer();
 	TableInfo  *tblinfo;
 	int			i_reltableoid;
 	int			i_reloid;
@@ -3192,6 +3199,21 @@ getTables(int *numTables)
 	i_reltablespace = PQfnumber(res, "reltablespace");
 	i_reloptions = PQfnumber(res, "reloptions");
 
+	if (lockWaitTimeout && g_fout->remoteVersion >= 70300)
+	{
+		/*
+		 * Arrange to fail instead of waiting forever for a table lock.
+		 *
+		 * NB: this coding assumes that the only queries issued within
+		 * the following loop are LOCK TABLEs; else the timeout may be
+		 * undesirably applied to other things too.
+		 */
+		resetPQExpBuffer(query);
+		appendPQExpBuffer(query, "SET statement_timeout = ");
+		appendStringLiteralConn(query, lockWaitTimeout, g_conn);
+		do_sql_command(g_conn, query->data);
+	}
+
 	for (i = 0; i < ntups; i++)
 	{
 		tblinfo[i].dobj.objType = DO_TABLE;
@@ -3246,12 +3268,12 @@ getTables(int *numTables)
 		 */
 		if (tblinfo[i].dobj.dump && tblinfo[i].relkind == RELKIND_RELATION)
 		{
-			resetPQExpBuffer(lockquery);
+			resetPQExpBuffer(query);
-			appendPQExpBuffer(lockquery,
+			appendPQExpBuffer(query,
 							  "LOCK TABLE %s IN ACCESS SHARE MODE",
 						 fmtQualifiedId(tblinfo[i].dobj.namespace->dobj.name,
 										tblinfo[i].dobj.name));
-			do_sql_command(g_conn, lockquery->data);
+			do_sql_command(g_conn, query->data);
 		}
 
 		/* Emit notice if join for owner failed */
@@ -3260,6 +3282,11 @@ getTables(int *numTables)
 					  tblinfo[i].dobj.name);
 	}
 
+	if (lockWaitTimeout && g_fout->remoteVersion >= 70300)
+	{
+		do_sql_command(g_conn, "SET statement_timeout = 0");
+	}
+
 	PQclear(res);
 
 	/*
@@ -3292,8 +3319,6 @@ getTables(int *numTables)
 	}
 
 	destroyPQExpBuffer(query);
-	destroyPQExpBuffer(delqry);
-	destroyPQExpBuffer(lockquery);
 
 	return tblinfo;
 }