On 10/06/10 09:42, Fujii Masao wrote:
On Thu, Jun 10, 2010 at 11:56 AM, Tom Lane<t...@sss.pgh.pa.us> wrote:
Robert Haas<robertmh...@gmail.com> writes:
On Wed, Jun 9, 2010 at 9:46 PM, Takahiro Itagaki
<itagaki.takah...@oss.ntt.co.jp> wrote:
I found a term "InvalidXLogRecPtr" in 9.0 docs.
http://developer.postgresql.org/pgdocs/postgres/functions-admin.html#FUNCTIONS-RECOVERY-INFO-TABLE
| ... then the return value will be InvalidXLogRecPtr (0/0).
Maybe we should be returning NULL instead of 0/0.
+1 for using NULL instead of an artificially chosen value, for both of
those functions.
Okay, the attached patch makes those functions return NULL in that case.
Ah, I just committed a patch to do the same, before seeing your email.
Thanks anyway.
BTW, the docs claim about pg_last_xlog_location() that "While streaming
replication is in progress this will increase monotonically." That's a
bit misleading: when the replication connection is broken for some
reason and we restart it, we begin streaming from the beginning of the
last WAL segment. So at that moment, pg_last_xlog_location() moves
backwards to the beginning of the WAL segment.
Should we:
1. Just document that,
2. Change pg_last_xlog_location() to not move backwards in that case, or
3. Change the behavior so that we start streaming at the exact byte
location where we left off?
I believe that starting from the beginning of the WAL segment is just
paranoia, to avoid creating a WAL file that's missing some data from the
beginning. Right?
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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