Change internal RelFileNode references to RelFileNumber or RelFileLocator.

We have been using the term RelFileNode to refer to either (1) the
integer that is used to name the sequence of files for a certain relation
within the directory set aside for that tablespace/database combination;
or (2) that value plus the OIDs of the tablespace and database; or
occasionally (3) the whole series of files created for a relation
based on those values. Using the same name for more than one thing is
confusing.

Replace RelFileNode with RelFileNumber when we're talking about just the
single number, i.e. (1) from above, and with RelFileLocator when we're
talking about all the things that are needed to locate a relation's files
on disk, i.e. (2) from above. In the places where we refer to (3) as
a relfilenode, instead refer to "relation storage".

Since there is a ton of SQL code in the world that knows about
pg_class.relfilenode, don't change the name of that column, or of other
SQL-facing things that derive their name from it.

On the other hand, do adjust closely-related internal terminology. For
example, the structure member names dbNode and spcNode appear to be
derived from the fact that the structure itself was called RelFileNode,
so change those to dbOid and spcOid. Likewise, various variables with
names like rnode and relnode get renamed appropriately, according to
how they're being used in context.

Hopefully, this is clearer than before. It is also preparation for
future patches that intend to widen the relfilenumber fields from its
current width of 32 bits. Variables that store a relfilenumber are now
declared as type RelFileNumber rather than type Oid; right now, these
are the same, but that can now more easily be changed.

Dilip Kumar, per an idea from me. Reviewed also by Andres Freund.
I fixed some whitespace issues, changed a couple of words in a
comment, and made one other minor correction.

Discussion: http://postgr.es/m/CA+TgmoamOtXbVAQf9hWFzonUo6bhhjS6toZQd7HZ-pmojtAmag@mail.gmail.com
Discussion: http://postgr.es/m/CA+Tgmobp7+7kmi4gkq7Y+4AM9fTvL+O1oQ4-5gFTT+6Ng-dQ=g@mail.gmail.com
Discussion: http://postgr.es/m/CAFiTN-vTe79M8uDH1yprOU64MNFE+R3ODRuA+JWf27JbhY4hJw@mail.gmail.com

1 files changed, 9 insertions, 9 deletions

diff --git a/src/backend/commands/tablespace.c b/src/backend/commands/tablespace.c
index 00ca397fe88..c8bdd9992ac 100644
--- a/src/backend/commands/tablespace.c
+++ b/src/backend/commands/tablespace.c
@@ -12,12 +12,12 @@
  * remove the possibility of having file name conflicts, we isolate
  * files within a tablespace into database-specific subdirectories.
  *
- * To support file access via the information given in RelFileNode, we
+ * To support file access via the information given in RelFileLocator, we
  * maintain a symbolic-link map in $PGDATA/pg_tblspc. The symlinks are
  * named by tablespace OIDs and point to the actual tablespace directories.
  * There is also a per-cluster version directory in each tablespace.
  * Thus the full path to an arbitrary file is
- *			$PGDATA/pg_tblspc/spcoid/PG_MAJORVER_CATVER/dboid/relfilenode
+ *			$PGDATA/pg_tblspc/spcoid/PG_MAJORVER_CATVER/dboid/relfilenumber
  * e.g.
  *			$PGDATA/pg_tblspc/20981/PG_9.0_201002161/719849/83292814
  *
@@ -25,8 +25,8 @@
  * tables) and pg_default (for everything else).  For backwards compatibility
  * and to remain functional on platforms without symlinks, these tablespaces
  * are accessed specially: they are respectively
- *			$PGDATA/global/relfilenode
- *			$PGDATA/base/dboid/relfilenode
+ *			$PGDATA/global/relfilenumber
+ *			$PGDATA/base/dboid/relfilenumber
  *
  * To allow CREATE DATABASE to give a new database a default tablespace
  * that's different from the template database's default, we make the
@@ -115,7 +115,7 @@ static bool destroy_tablespace_directories(Oid tablespaceoid, bool redo);
  * re-create a database subdirectory (of $PGDATA/base) during WAL replay.
  */
 void
-TablespaceCreateDbspace(Oid spcNode, Oid dbNode, bool isRedo)
+TablespaceCreateDbspace(Oid spcOid, Oid dbOid, bool isRedo)
 {
 	struct stat st;
 	char	   *dir;
@@ -124,13 +124,13 @@ TablespaceCreateDbspace(Oid spcNode, Oid dbNode, bool isRedo)
 	 * The global tablespace doesn't have per-database subdirectories, so
 	 * nothing to do for it.
 	 */
-	if (spcNode == GLOBALTABLESPACE_OID)
+	if (spcOid == GLOBALTABLESPACE_OID)
 		return;
 
-	Assert(OidIsValid(spcNode));
-	Assert(OidIsValid(dbNode));
+	Assert(OidIsValid(spcOid));
+	Assert(OidIsValid(dbOid));
 
-	dir = GetDatabasePath(dbNode, spcNode);
+	dir = GetDatabasePath(dbOid, spcOid);
 
 	if (stat(dir, &st) < 0)
 	{