Comment - uniqueness of relfilenode
catalog/catalog.c:GetNewRelFileNode() and its calls indicate that the
following change makes sense:
diff --git a/src/include/storage/relfilenode.h
b/src/include/storage/relfilenode.h
index 75f897f..7190974 100644
--- a/src/include/storage/relfilenode.h
+++ b/src/include/storage/relfilenode.h
@@ -55,7 +55,7 @@ typedef enum ForkNumber
* relNode identifies the specific relation. relNode corresponds to
* pg_class.relfilenode (NOT pg_class.oid, because we need to be able
* to assign new physical files to relations in some situations).
- * Notice that relNode is only unique within a particular database.
+ * Notice that relNode is only unique within a particular tablespace.
*
* Note: spcNode must be GLOBALTABLESPACE_OID if and only if dbNode is
* zero. We support shared relations only in the "global" tablespace.// Antonin Houska (Tony)
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On Thu, Nov 7, 2013 at 10:56 AM, Antonin Houska
<antonin.houska@gmail.com> wrote:
catalog/catalog.c:GetNewRelFileNode() and its calls indicate that the
following change makes sense:diff --git a/src/include/storage/relfilenode.h b/src/include/storage/relfilenode.h index 75f897f..7190974 100644 --- a/src/include/storage/relfilenode.h +++ b/src/include/storage/relfilenode.h @@ -55,7 +55,7 @@ typedef enum ForkNumber * relNode identifies the specific relation. relNode corresponds to * pg_class.relfilenode (NOT pg_class.oid, because we need to be able * to assign new physical files to relations in some situations). - * Notice that relNode is only unique within a particular database. + * Notice that relNode is only unique within a particular tablespace. * * Note: spcNode must be GLOBALTABLESPACE_OID if and only if dbNode is * zero. We support shared relations only in the "global" tablespace.// Antonin Houska (Tony)
Technically speaking, I think it's only guaranteed to be unique with a
database-tablespace combination. In other words, the same OID can be
reused as a relfilenode if *either* of those two values differs.
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EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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On 11/10/2013 12:57 AM, Robert Haas wrote:
On Thu, Nov 7, 2013 at 10:56 AM, Antonin Houska
<antonin.houska@gmail.com> wrote:catalog/catalog.c:GetNewRelFileNode() and its calls indicate that the
following change makes sense:diff --git a/src/include/storage/relfilenode.h b/src/include/storage/relfilenode.h index 75f897f..7190974 100644 --- a/src/include/storage/relfilenode.h +++ b/src/include/storage/relfilenode.h @@ -55,7 +55,7 @@ typedef enum ForkNumber * relNode identifies the specific relation. relNode corresponds to * pg_class.relfilenode (NOT pg_class.oid, because we need to be able * to assign new physical files to relations in some situations). - * Notice that relNode is only unique within a particular database. + * Notice that relNode is only unique within a particular tablespace. * * Note: spcNode must be GLOBALTABLESPACE_OID if and only if dbNode is * zero. We support shared relations only in the "global" tablespace.// Antonin Houska (Tony)
Technically speaking, I think it's only guaranteed to be unique with a
database-tablespace combination. In other words, the same OID can be
reused as a relfilenode if *either* of those two values differs.
You're right. I missed the fact that Postgres (unlike another DBMS that
I worked with) allows for tablespace to be shared across databases.
// Antonin Houska (Tony)
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On Mon, Nov 11, 2013 at 05:48:52PM +0100, Antonin Houska wrote:
On 11/10/2013 12:57 AM, Robert Haas wrote:
On Thu, Nov 7, 2013 at 10:56 AM, Antonin Houska
<antonin.houska@gmail.com> wrote:catalog/catalog.c:GetNewRelFileNode() and its calls indicate that the
following change makes sense:diff --git a/src/include/storage/relfilenode.h b/src/include/storage/relfilenode.h index 75f897f..7190974 100644 --- a/src/include/storage/relfilenode.h +++ b/src/include/storage/relfilenode.h @@ -55,7 +55,7 @@ typedef enum ForkNumber * relNode identifies the specific relation. relNode corresponds to * pg_class.relfilenode (NOT pg_class.oid, because we need to be able * to assign new physical files to relations in some situations). - * Notice that relNode is only unique within a particular database. + * Notice that relNode is only unique within a particular tablespace. * * Note: spcNode must be GLOBALTABLESPACE_OID if and only if dbNode is * zero. We support shared relations only in the "global" tablespace.// Antonin Houska (Tony)
Technically speaking, I think it's only guaranteed to be unique with a
database-tablespace combination. In other words, the same OID can be
reused as a relfilenode if *either* of those two values differs.You're right. I missed the fact that Postgres (unlike another DBMS that
I worked with) allows for tablespace to be shared across databases.
I have update the C comment:
< * Notice that relNode is only unique within a particular database.
---
* Notice that relNode is only unique within a particular tablespace.
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ Everyone has their own god. +
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On Wed, Mar 5, 2014 at 8:54 PM, Bruce Momjian <bruce@momjian.us> wrote:
On Mon, Nov 11, 2013 at 05:48:52PM +0100, Antonin Houska wrote:
On 11/10/2013 12:57 AM, Robert Haas wrote:
On Thu, Nov 7, 2013 at 10:56 AM, Antonin Houska
<antonin.houska@gmail.com> wrote:catalog/catalog.c:GetNewRelFileNode() and its calls indicate that the
following change makes sense:diff --git a/src/include/storage/relfilenode.h b/src/include/storage/relfilenode.h index 75f897f..7190974 100644 --- a/src/include/storage/relfilenode.h +++ b/src/include/storage/relfilenode.h @@ -55,7 +55,7 @@ typedef enum ForkNumber * relNode identifies the specific relation. relNode corresponds to * pg_class.relfilenode (NOT pg_class.oid, because we need to be able * to assign new physical files to relations in some situations). - * Notice that relNode is only unique within a particular database. + * Notice that relNode is only unique within a particular tablespace. * * Note: spcNode must be GLOBALTABLESPACE_OID if and only if dbNode is * zero. We support shared relations only in the "global" tablespace.// Antonin Houska (Tony)
Technically speaking, I think it's only guaranteed to be unique with a
database-tablespace combination. In other words, the same OID can be
reused as a relfilenode if *either* of those two values differs.You're right. I missed the fact that Postgres (unlike another DBMS that
I worked with) allows for tablespace to be shared across databases.I have update the C comment:
< * Notice that relNode is only unique within a particular database.
---* Notice that relNode is only unique within a particular tablespace.
Yep. But the new text is no more correct than the old text. Did you
read what I wrote upthread?
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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On 03/06/2014 04:33 AM, Robert Haas wrote:
On Wed, Mar 5, 2014 at 8:54 PM, Bruce Momjian <bruce@momjian.us> wrote:
On Mon, Nov 11, 2013 at 05:48:52PM +0100, Antonin Houska wrote:
On 11/10/2013 12:57 AM, Robert Haas wrote:
On Thu, Nov 7, 2013 at 10:56 AM, Antonin Houska
<antonin.houska@gmail.com> wrote:catalog/catalog.c:GetNewRelFileNode() and its calls indicate that the
following change makes sense:diff --git a/src/include/storage/relfilenode.h b/src/include/storage/relfilenode.h index 75f897f..7190974 100644 --- a/src/include/storage/relfilenode.h +++ b/src/include/storage/relfilenode.h @@ -55,7 +55,7 @@ typedef enum ForkNumber * relNode identifies the specific relation. relNode corresponds to * pg_class.relfilenode (NOT pg_class.oid, because we need to be able * to assign new physical files to relations in some situations). - * Notice that relNode is only unique within a particular database. + * Notice that relNode is only unique within a particular tablespace. * * Note: spcNode must be GLOBALTABLESPACE_OID if and only if dbNode is * zero. We support shared relations only in the "global" tablespace.// Antonin Houska (Tony)
Technically speaking, I think it's only guaranteed to be unique with a
database-tablespace combination. In other words, the same OID can be
reused as a relfilenode if *either* of those two values differs.You're right. I missed the fact that Postgres (unlike another DBMS that
I worked with) allows for tablespace to be shared across databases.I have update the C comment:
< * Notice that relNode is only unique within a particular database.
---* Notice that relNode is only unique within a particular tablespace.
Yep. But the new text is no more correct than the old text. Did you
read what I wrote upthread?
Perhaps "... unique within a particular (tablespace, database)
combination." ?
// Tony
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On Thu, Mar 6, 2014 at 08:34:29AM +0100, Antonin Houska wrote:
You're right. I missed the fact that Postgres (unlike another DBMS that
I worked with) allows for tablespace to be shared across databases.I have update the C comment:
< * Notice that relNode is only unique within a particular database.
---* Notice that relNode is only unique within a particular tablespace.
Yep. But the new text is no more correct than the old text. Did you
read what I wrote upthread?Perhaps "... unique within a particular (tablespace, database)
combination." ?
Oh, I thought people just wanted the text to be consistent with other
mentions, rather than improving it. Attached is a patch which updates
comments about the tablespace/database issue.
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ Everyone has their own god. +
Attachments:
relfilenode.difftext/x-diff; charset=us-asciiDownload+11-11
On Thu, Mar 6, 2014 at 09:20:39PM -0500, Bruce Momjian wrote:
On Thu, Mar 6, 2014 at 08:34:29AM +0100, Antonin Houska wrote:
You're right. I missed the fact that Postgres (unlike another DBMS that
I worked with) allows for tablespace to be shared across databases.I have update the C comment:
< * Notice that relNode is only unique within a particular database.
---* Notice that relNode is only unique within a particular tablespace.
Yep. But the new text is no more correct than the old text. Did you
read what I wrote upthread?Perhaps "... unique within a particular (tablespace, database)
combination." ?Oh, I thought people just wanted the text to be consistent with other
mentions, rather than improving it. Attached is a patch which updates
comments about the tablespace/database issue.
Applied.
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ Everyone has their own god. +
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