On 02.02.2012 08:19, Simon Riggs wrote:
On Wed, Feb 1, 2012 at 10:42 PM, Jim Nasby<j...@nasby.net> wrote:
On Feb 1, 2012, at 4:25 AM, Simon Riggs wrote:
At present log_newpage() produces log records called XLOG_HEAP_NEWPAGE.
That routine is used by HEAP, BTREE, GIN, SPGIST rmgrs, as well as
various forks.
WAL contains no information as to which rmgr the data refers to,
making debugging much harder and skewing efforts to optimise WAL
traffic and is a pretty gross modularity violation of the whole rmgr
concept.
This refactoring adds an RmgrId field onto each new page record and
makes clearer that certain "heap" routines are actually generic. The
WAL records are still marked as HEAP rmgr and have XLOG_NEWPAGE record
type, but at least we can tell them apart. (We already had forknum,
just not rmgrid).
But we already had RelFileNode; wouldn't that be enough to tell what rmgr was
responsible for the new page? Can 2 different rmgrs write to the same file node?
No, but which one? No way to tell unless you have full list of
relfilenodes and check each one.
Well, you can obviously check the catalogs for that, but you must be
assuming that you don't have access to the catalogs or this would be a
non-issue.
You can also identify the kind of page by looking at the special area of
the stored page. See:
http://archives.postgresql.org/pgsql-hackers/2007-04/msg00392.php
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
