Обсуждение: pg_last_xlog_receive_location()
In my understanding pg_last_xlog_receive_location() returns NULL if applied to non standby server: Get last transaction log location received and synced to disk by streaming replication. While streaming replication is in progress this will increase monotonically. But when streaming replication is restarted this will back off to the replication starting position, typically the beginning of the WAL file containing the current replay location. If recovery has completed this will remain static at the value of the last WAL record received and synced to disk during recovery. If streaming replication is disabled, or if it has not yet started, the function returns NULL. However my primary server returns non NULL. Am I missing something? -- Tatsuo Ishii SRA OSS, Inc. Japan English: http://www.sraoss.co.jp/index_en.php Japanese: http://www.sraoss.co.jp
On Wed, Mar 30, 2011 at 10:13 AM, Tatsuo Ishii <ishii@postgresql.org> wrote: > In my understanding pg_last_xlog_receive_location() returns NULL if > applied to non standby server: > > Get last transaction log location received and synced to disk by > streaming replication. While streaming replication is in progress this > will increase monotonically. But when streaming replication is > restarted this will back off to the replication starting position, > typically the beginning of the WAL file containing the current replay > location. If recovery has completed this will remain static at the > value of the last WAL record received and synced to disk during > recovery. If streaming replication is disabled, or if it has not yet > started, the function returns NULL. > > However my primary server returns non NULL. Am I missing something? In the primary server which was brought up from the standby, pg_last_xlog_receive_location() returns non-NULL. Regards, -- Fujii Masao NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center
> In the primary server which was brought up from the standby, > pg_last_xlog_receive_location() returns non-NULL. Thanks. BTW, is there any reliable way to know a standby is promoting to primary? -- Tatsuo Ishii SRA OSS, Inc. Japan English: http://www.sraoss.co.jp/index_en.php Japanese: http://www.sraoss.co.jp
On Wed, Mar 30, 2011 at 11:08 AM, Tatsuo Ishii <ishii@postgresql.org> wrote: > BTW, is there any reliable way to know a standby is promoting to > primary? You can know that from the server log. But there is no way to do that via SQL, I think. Regards, -- Fujii Masao NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center
>> BTW, is there any reliable way to know a standby is promoting to >> primary? > > You can know that from the server log. But there is no way to do that > via SQL, I think. Ok. It seems I need to patch PostgreSQL. -- Tatsuo Ishii SRA OSS, Inc. Japan English: http://www.sraoss.co.jp/index_en.php Japanese: http://www.sraoss.co.jp
On Tue, Mar 29, 2011 at 9:08 PM, Tatsuo Ishii <ishii@postgresql.org> wrote: >> In the primary server which was brought up from the standby, >> pg_last_xlog_receive_location() returns non-NULL. > > Thanks. > > BTW, is there any reliable way to know a standby is promoting to > primary? if you know the server was a standby and pg_is_in_recovery() returns false then it was promoted. is that what you want to know? or i misunderstood you? -- Jaime Casanova www.2ndQuadrant.com Professional PostgreSQL: Soporte y capacitación de PostgreSQL
On Wed, Mar 30, 2011 at 11:45 AM, Tatsuo Ishii <ishii@postgresql.org> wrote: >>> BTW, is there any reliable way to know a standby is promoting to >>> primary? >> >> You can know that from the server log. But there is no way to do that >> via SQL, I think. > > Ok. It seems I need to patch PostgreSQL. Why is that feature required? It's for pgpool-II? Regards, -- Fujii Masao NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center
>> Ok. It seems I need to patch PostgreSQL. > > Why is that feature required? It's for pgpool-II? Yes. And probably any automated failover management tool will require the functionality. -- Tatsuo Ishii SRA OSS, Inc. Japan English: http://www.sraoss.co.jp/index_en.php Japanese: http://www.sraoss.co.jp