Include the backend ID in the relpath of temporary relations.

This allows us to reliably remove all leftover temporary relation
files on cluster startup without reference to system catalogs or WAL;
therefore, we no longer include temporary relations in XLOG_XACT_COMMIT
and XLOG_XACT_ABORT WAL records.

Since these changes require including a backend ID in each
SharedInvalSmgrMsg, the size of the SharedInvalidationMessage.id
field has been reduced from two bytes to one, and the maximum number
of connections has been reduced from INT_MAX / 4 to 2^23-1.  It would
be possible to remove these restrictions by increasing the size of
SharedInvalidationMessage by 4 bytes, but right now that doesn't seem
like a good trade-off.

Review by Jaime Casanova and Tom Lane.

1 files changed, 32 insertions, 11 deletions

diff --git a/src/backend/utils/adt/dbsize.c b/src/backend/utils/adt/dbsize.c
index e11c13a9ccf..01a4a17915d 100644
--- a/src/backend/utils/adt/dbsize.c
+++ b/src/backend/utils/adt/dbsize.c
@@ -5,7 +5,7 @@
  * Copyright (c) 2002-2010, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/dbsize.c,v 1.32 2010/08/05 14:45:04 rhaas Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/dbsize.c,v 1.33 2010/08/13 20:10:52 rhaas Exp $
  *
  */
 
@@ -244,14 +244,14 @@ pg_tablespace_size_name(PG_FUNCTION_ARGS)
  * calculate size of (one fork of) a relation
  */
 static int64
-calculate_relation_size(RelFileNode *rfn, ForkNumber forknum)
+calculate_relation_size(RelFileNode *rfn, BackendId backend, ForkNumber forknum)
 {
 	int64		totalsize = 0;
 	char	   *relationpath;
 	char		pathname[MAXPGPATH];
 	unsigned int segcount = 0;
 
-	relationpath = relpath(*rfn, forknum);
+	relationpath = relpathbackend(*rfn, backend, forknum);
 
 	for (segcount = 0;; segcount++)
 	{
@@ -291,7 +291,7 @@ pg_relation_size(PG_FUNCTION_ARGS)
 
 	rel = relation_open(relOid, AccessShareLock);
 
-	size = calculate_relation_size(&(rel->rd_node),
+	size = calculate_relation_size(&(rel->rd_node), rel->rd_backend,
 							  forkname_to_number(text_to_cstring(forkName)));
 
 	relation_close(rel, AccessShareLock);
@@ -315,12 +315,14 @@ calculate_toast_table_size(Oid toastrelid)
 
 	/* toast heap size, including FSM and VM size */
 	for (forkNum = 0; forkNum <= MAX_FORKNUM; forkNum++)
-		size += calculate_relation_size(&(toastRel->rd_node), forkNum);
+		size += calculate_relation_size(&(toastRel->rd_node),
+										toastRel->rd_backend, forkNum);
 
 	/* toast index size, including FSM and VM size */
 	toastIdxRel = relation_open(toastRel->rd_rel->reltoastidxid, AccessShareLock);
 	for (forkNum = 0; forkNum <= MAX_FORKNUM; forkNum++)
-		size += calculate_relation_size(&(toastIdxRel->rd_node), forkNum);
+		size += calculate_relation_size(&(toastIdxRel->rd_node),
+										toastIdxRel->rd_backend, forkNum);
 
 	relation_close(toastIdxRel, AccessShareLock);
 	relation_close(toastRel, AccessShareLock);
@@ -349,7 +351,8 @@ calculate_table_size(Oid relOid)
 	 * heap size, including FSM and VM
 	 */
 	for (forkNum = 0; forkNum <= MAX_FORKNUM; forkNum++)
-		size += calculate_relation_size(&(rel->rd_node), forkNum);
+		size += calculate_relation_size(&(rel->rd_node), rel->rd_backend,
+										forkNum);
 
 	/*
 	 * Size of toast relation
@@ -392,7 +395,9 @@ calculate_indexes_size(Oid relOid)
 			idxRel = relation_open(idxOid, AccessShareLock);
 
 			for (forkNum = 0; forkNum <= MAX_FORKNUM; forkNum++)
-				size += calculate_relation_size(&(idxRel->rd_node), forkNum);
+				size += calculate_relation_size(&(idxRel->rd_node),
+												idxRel->rd_backend,
+												forkNum);
 
 			relation_close(idxRel, AccessShareLock);
 		}
@@ -563,6 +568,7 @@ pg_relation_filepath(PG_FUNCTION_ARGS)
 	HeapTuple	tuple;
 	Form_pg_class relform;
 	RelFileNode rnode;
+	BackendId	backend;
 	char	   *path;
 
 	tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
@@ -600,12 +606,27 @@ pg_relation_filepath(PG_FUNCTION_ARGS)
 			break;
 	}
 
-	ReleaseSysCache(tuple);
-
 	if (!OidIsValid(rnode.relNode))
+	{
+		ReleaseSysCache(tuple);
 		PG_RETURN_NULL();
+	}
+
+	/* If temporary, determine owning backend. */
+	if (!relform->relistemp)
+		backend = InvalidBackendId;
+	else if (isTempOrToastNamespace(relform->relnamespace))
+		backend = MyBackendId;
+	else
+	{
+		/* Do it the hard way. */
+		backend = GetTempNamespaceBackendId(relform->relnamespace);
+		Assert(backend != InvalidBackendId);
+	}
+
+	ReleaseSysCache(tuple);
 
-	path = relpath(rnode, MAIN_FORKNUM);
+	path = relpathbackend(rnode, backend, MAIN_FORKNUM);
 
 	PG_RETURN_TEXT_P(cstring_to_text(path));
 }