Further dtrace adjustments for the backend-IDs-in-relpath patch.

Update the documentation, and back out a few ill-considered changes
whose folly I failed to realize for failure to read the documentation.

doc/src/sgml/monitoring.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/monitoring.sgml,v 1.82 2010/08/08 16:27:03 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/monitoring.sgml,v 1.83 2010/08/14 02:22:10 rhaas Exp $ -->
 
 <chapter id="monitoring">
  <title>Monitoring Database Activity</title>
@@ -1436,26 +1436,28 @@ SELECT pg_stat_get_backend_pid(s.backendid) AS procpid,
     </row>
     <row>
      <entry>buffer-read-start</entry>
-     <entry>(ForkNumber, BlockNumber, Oid, Oid, Oid, bool, bool)</entry>
+     <entry>(ForkNumber, BlockNumber, Oid, Oid, Oid, int, bool)</entry>
      <entry>Probe that fires when a buffer read is started.
       arg0 and arg1 contain the fork and block numbers of the page (but
       arg1 will be -1 if this is a relation extension request).
       arg2, arg3, and arg4 contain the tablespace, database, and relation OIDs
       identifying the relation.
-      arg5 is true for a local buffer, false for a shared buffer.
+      arg5 is the ID of the backend which created the temporary relation for a
+      local buffer, or InvalidBackendId (-1) for a shared buffer.
       arg6 is true for a relation extension request, false for normal
       read.</entry>
     </row>
     <row>
      <entry>buffer-read-done</entry>
-     <entry>(ForkNumber, BlockNumber, Oid, Oid, Oid, bool, bool, bool)</entry>
+     <entry>(ForkNumber, BlockNumber, Oid, Oid, Oid, int, bool, bool)</entry>
      <entry>Probe that fires when a buffer read is complete.
       arg0 and arg1 contain the fork and block numbers of the page (if this
       is a relation extension request, arg1 now contains the block number
       of the newly added block).
       arg2, arg3, and arg4 contain the tablespace, database, and relation OIDs
       identifying the relation.
-      arg5 is true for a local buffer, false for a shared buffer.
+      arg5 is the ID of the backend which created the temporary relation for a
+      local buffer, or InvalidBackendId (-1) for a shared buffer.
       arg6 is true for a relation extension request, false for normal
       read.
       arg7 is true if the buffer was found in the pool, false if not.</entry>
@@ -1521,38 +1523,46 @@ SELECT pg_stat_get_backend_pid(s.backendid) AS procpid,
     </row>
     <row>
      <entry>smgr-md-read-start</entry>
-     <entry>(ForkNumber, BlockNumber, Oid, Oid, Oid)</entry>
+     <entry>(ForkNumber, BlockNumber, Oid, Oid, Oid, int)</entry>
      <entry>Probe that fires when beginning to read a block from a relation.
       arg0 and arg1 contain the fork and block numbers of the page.
       arg2, arg3, and arg4 contain the tablespace, database, and relation OIDs
-      identifying the relation.</entry>
+      identifying the relation.
+      arg5 is the ID of the backend which created the temporary relation for a
+      local buffer, or InvalidBackendId (-1) for a shared buffer.</entry>
     </row>
     <row>
      <entry>smgr-md-read-done</entry>
-     <entry>(ForkNumber, BlockNumber, Oid, Oid, Oid, int, int)</entry>
+     <entry>(ForkNumber, BlockNumber, Oid, Oid, Oid, int, int, int)</entry>
      <entry>Probe that fires when a block read is complete.
       arg0 and arg1 contain the fork and block numbers of the page.
       arg2, arg3, and arg4 contain the tablespace, database, and relation OIDs
       identifying the relation.
-      arg5 is the number of bytes actually read, while arg6 is the number
+      arg5 is the ID of the backend which created the temporary relation for a
+      local buffer, or InvalidBackendId (-1) for a shared buffer.
+      arg6 is the number of bytes actually read, while arg7 is the number
       requested (if these are different it indicates trouble).</entry>
     </row>
     <row>
      <entry>smgr-md-write-start</entry>
-     <entry>(ForkNumber, BlockNumber, Oid, Oid, Oid)</entry>
+     <entry>(ForkNumber, BlockNumber, Oid, Oid, Oid, int)</entry>
      <entry>Probe that fires when beginning to write a block to a relation.
       arg0 and arg1 contain the fork and block numbers of the page.
       arg2, arg3, and arg4 contain the tablespace, database, and relation OIDs
-      identifying the relation.</entry>
+      identifying the relation.
+      arg5 is the ID of the backend which created the temporary relation for a
+      local buffer, or InvalidBackendId (-1) for a shared buffer.</entry>
     </row>
     <row>
      <entry>smgr-md-write-done</entry>
-     <entry>(ForkNumber, BlockNumber, Oid, Oid, Oid, int, int)</entry>
+     <entry>(ForkNumber, BlockNumber, Oid, Oid, Oid, int, int, int)</entry>
      <entry>Probe that fires when a block write is complete.
       arg0 and arg1 contain the fork and block numbers of the page.
       arg2, arg3, and arg4 contain the tablespace, database, and relation OIDs
       identifying the relation.
-      arg5 is the number of bytes actually written, while arg6 is the number
+      arg5 is the ID of the backend which created the temporary relation for a
+      local buffer, or InvalidBackendId (-1) for a shared buffer.
+      arg6 is the number of bytes actually written, while arg7 is the number
       requested (if these are different it indicates trouble).</entry>
     </row>
     <row>

src/backend/storage/buffer/bufmgr.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.258 2010/08/13 22:54:17 rhaas Exp $
+ *	  $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.259 2010/08/14 02:22:10 rhaas Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1852,8 +1852,7 @@ FlushBuffer(volatile BufferDesc *buf, SMgrRelation reln)
 										buf->tag.blockNum,
 										reln->smgr_rnode.node.spcNode,
 										reln->smgr_rnode.node.dbNode,
-										reln->smgr_rnode.node.relNode,
-										reln->smgr_rnode.backend);
+										reln->smgr_rnode.node.relNode);
 
 	/*
 	 * Force XLOG flush up to buffer's LSN.  This implements the basic WAL
@@ -1892,8 +1891,7 @@ FlushBuffer(volatile BufferDesc *buf, SMgrRelation reln)
 									   buf->tag.blockNum,
 									   reln->smgr_rnode.node.spcNode,
 									   reln->smgr_rnode.node.dbNode,
-									   reln->smgr_rnode.node.relNode,
-									   reln->smgr_rnode.backend);
+									   reln->smgr_rnode.node.relNode);
 
 	/* Pop the error context stack */
 	error_context_stack = errcontext.previous;

src/backend/utils/probes.d

@@ -3,7 +3,7 @@
  *
  *	Copyright (c) 2006-2010, PostgreSQL Global Development Group
  *
- *	$PostgreSQL: pgsql/src/backend/utils/probes.d,v 1.14 2010/08/13 22:54:17 rhaas Exp $
+ *	$PostgreSQL: pgsql/src/backend/utils/probes.d,v 1.15 2010/08/14 02:22:10 rhaas Exp $
  * ----------
  */
 
@@ -56,8 +56,8 @@ provider postgresql {
 
 	probe buffer__read__start(ForkNumber, BlockNumber, Oid, Oid, Oid, int, bool);
 	probe buffer__read__done(ForkNumber, BlockNumber, Oid, Oid, Oid, int, bool, bool);
-	probe buffer__flush__start(ForkNumber, BlockNumber, Oid, Oid, Oid, int);
-	probe buffer__flush__done(ForkNumber, BlockNumber, Oid, Oid, Oid, int);
+	probe buffer__flush__start(ForkNumber, BlockNumber, Oid, Oid, Oid);
+	probe buffer__flush__done(ForkNumber, BlockNumber, Oid, Oid, Oid);
 
 	probe buffer__checkpoint__start(int);
 	probe buffer__checkpoint__sync__start();