Re: [HACKERS] Hi- How frequently Postgres Poll for trigger file
On 03.12.2010 03:55, Fujii Masao wrote: On Thu, Dec 2, 2010 at 12:16 AM, Euler Taveira de Oliveira eu...@timbira.com wrote: As you said, there are platforms that a signal doesn't wake up a process, so I suggest (ii) but I'm fine to include (i) at docs too. Can we use pg_ctl kill to send signal on such platforms? It won't make a difference, pg_ctl kill sends the signal just like regular kill. Except that pg_ctl kill also works on Windows which doesn't have the concept of Unix signals. -- 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
Re: [HACKERS] Hi- How frequently Postgres Poll for trigger file
Hey!1 I am able to change the switch over time.. Thanks alot.. 2010/12/2 aaliya zarrin aaliya.zar...@gmail.com Ok.. Thanks I will try!!! 2010/12/2 Heikki Linnakangas heikki.linnakan...@enterprisedb.com Oh, and there's another value for the case we're polling the archive, not streaming from master. Search for 5 in XLogPageRead function to catch them all. On 02.12.2010 08:21, Heikki Linnakangas wrote: It's the 500L argument in the WaitLatch call. It's expressed in microseconds. On 02.12.2010 06:39, aaliya zarrin wrote: Where this 5 Seconds time is defined in the code ??? On Wed, Dec 1, 2010 at 5:53 PM, Heikki Linnakangas heikki.linnakan...@enterprisedb.com wrote: On 01.12.2010 13:27, aaliya zarrin wrote: I want to know how frequently postgres search for trigger file to switch over. In 9.0, every 100ms while streaming replication is active and connected. 5 seconds otherwise. In current git master branch, it's always 5 s. Can this switch over time be reduced? Not without hacking the sources and compiling. Although, on many platforms, Linux included I believe, sending a signal to the startup process should wake it up from the sleep and make it check the trigger file immediately. pg_ctl reload for example should do it. So if ıou send a signal to the startup process immediately after creating the trigger file, it should take notice sooner. Plz let me know where postgres poll for trigger file. I could find it out in backend/access/trans/xlog.c ? am i right? Yes. search for callers of CheckForStandbyTrigger() function. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com -- Thanks Regards, Aaliya Zarrin (+91)-9160665888 -- Thanks Regards, Aaliya Zarrin (+91)-9160665888
Re: [HACKERS] Hi- How frequently Postgres Poll for trigger file
On Thu, Dec 2, 2010 at 12:16 AM, Euler Taveira de Oliveira eu...@timbira.com wrote: As you said, there are platforms that a signal doesn't wake up a process, so I suggest (ii) but I'm fine to include (i) at docs too. Can we use pg_ctl kill to send signal on such platforms? Regards, -- Fujii Masao NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
[HACKERS] Hi- How frequently Postgres Poll for trigger file
Hi All, I am new to postgres. I want to know how frequently postgres search for trigger file to switch over. Can this switch over time be reduced? Plz let me know where postgres poll for trigger file. I could find it out in backend/access/trans/xlog.c ? am i right? -- Thanks Regards, Aaliya Zarrin (+91)-9160665888
Re: [HACKERS] Hi- How frequently Postgres Poll for trigger file
On 01.12.2010 13:27, aaliya zarrin wrote: I want to know how frequently postgres search for trigger file to switch over. In 9.0, every 100ms while streaming replication is active and connected. 5 seconds otherwise. In current git master branch, it's always 5 s. Can this switch over time be reduced? Not without hacking the sources and compiling. Although, on many platforms, Linux included I believe, sending a signal to the startup process should wake it up from the sleep and make it check the trigger file immediately. pg_ctl reload for example should do it. So if ýou send a signal to the startup process immediately after creating the trigger file, it should take notice sooner. Plz let me know where postgres poll for trigger file. I could find it out in backend/access/trans/xlog.c ? am i right? Yes. search for callers of CheckForStandbyTrigger() function. -- 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
Re: [HACKERS] Hi- How frequently Postgres Poll for trigger file
Heikki Linnakangas escreveu: On 01.12.2010 13:27, aaliya zarrin wrote: I want to know how frequently postgres search for trigger file to switch over. In 9.0, every 100ms while streaming replication is active and connected. 5 seconds otherwise. In current git master branch, it's always 5 s. Can this switch over time be reduced? Not without hacking the sources and compiling. Although, on many platforms, Linux included I believe, sending a signal to the startup process should wake it up from the sleep and make it check the trigger file immediately. pg_ctl reload for example should do it. So if ýou send a signal to the startup process immediately after creating the trigger file, it should take notice sooner. Isn't it an ugly solution for stopping the replication immediately? At the top of my head, I don't remember the reason for not turn the interval for pooling trigger file into a configurable option. IMHO, high availability fits into those cases (switchover immediately). [poking the git history a little...] I agree the a short polling interval is not energy efficient [1] but some scenarios need this short interval. So if we want to stop the replication immediately, we have two options: (i) advertise that we need to signal the postmaster after creating a trigger file or (ii) made the pooling interval configurable. As you said, there are platforms that a signal doesn't wake up a process, so I suggest (ii) but I'm fine to include (i) at docs too. Comments? [1] http://git.postgresql.org/gitweb?p=postgresql.git;a=commitdiff;h=723d0184e2972f21db0f85feef3d35f0cb9b3298 -- Euler Taveira de Oliveira http://www.timbira.com/ -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Hi- How frequently Postgres Poll for trigger file
Thanks for quick response.. Can I change this 5 second time? I have seen the postgres code as well. What is the functionality of WaitLatch() function. I could not understand completely. Plz help.. On Wed, Dec 1, 2010 at 5:53 PM, Heikki Linnakangas heikki.linnakan...@enterprisedb.com wrote: On 01.12.2010 13:27, aaliya zarrin wrote: I want to know how frequently postgres search for trigger file to switch over. In 9.0, every 100ms while streaming replication is active and connected. 5 seconds otherwise. In current git master branch, it's always 5 s. Can this switch over time be reduced? Not without hacking the sources and compiling. Although, on many platforms, Linux included I believe, sending a signal to the startup process should wake it up from the sleep and make it check the trigger file immediately. pg_ctl reload for example should do it. So if ıou send a signal to the startup process immediately after creating the trigger file, it should take notice sooner. Plz let me know where postgres poll for trigger file. I could find it out in backend/access/trans/xlog.c ? am i right? Yes. search for callers of CheckForStandbyTrigger() function. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com -- Thanks Regards, Aaliya Zarrin (+91)-9160665888
Re: [HACKERS] Hi- How frequently Postgres Poll for trigger file
On 01.12.2010 19:23, aaliya zarrin wrote: Thanks for quick response.. Can I change this 5 second time? I have seen the postgres code as well. You can, if you don't mind changing the sources. What is the functionality of WaitLatch() function. I could not understand completely. The recoveryWakupLatch latch allows the startup process to wake up immediately when new WAL arrives via streaming replication, without waiting for the whole five seconds to elapse. -- 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
