<div dir="ltr">1. failover_command : this will usually be a shell script. The script will do a standby promote on new master, so there is no reason that it would fail and I believe it is over-engineering to do more than that. But since this is a script, you are free to put what you want in it : if you want to check the result of the standby promote and if it fails try on the third node, it is possible.<br><br><br>> Yep understood thanks. But i was looking for more of an automatic retry. So if pgpool cannot promote a new postgres master for some resaon and failover failed, i was expecting it to promote other nodes that are avialable in the quorum<br><br><br><br>2. pgpool does not support switch-over, you would have to stop the primary postgres database and let pgpool trigger the failover and then run a pcp_recovery on the old primary postgres<br><br><br><br>> Ok. So the reason behind the ask was if pgpool is not going to retry the promote on other nodes, I was thinking i can just trigger a force promote there by failover and follow master will be run by pgpool itself and i dont have to do a failover by myself and run pcp_recovery on all the nodes<br><br><br><br>Regarding 5. It's normal. Don't worry.<br><br>When a standby PostgreSQL node is added, existing connections to<br>Pgpool-II are kept (thus do not use the new standby for load<br>balacing). After the session ends, Pgpool-II child process checks<br>whether the failback has happend. If happend, exits itself so that new<br>process is spwan to reflect the fact that new standby node has been<br>added (thus it can use the new standby for load balancing).<br><br><br><br><br>> Thanks. Per my understanding, So restart happens only when a new standby is added is it. Because i see this frequent restarts happening even when there is no fallback.<br><br>Also could you please share some light on when the failback_command gets executed? I have never seen the command being called.<br><div><br></div><div><br></div><div>Thanks And Regards,</div><div><br></div><div> Lakshmi Y M</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, May 21, 2019 at 8:02 PM Lakshmi Raghavendra <<a href="mailto:lakshmiym108@gmail.com">lakshmiym108@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div dir="ltr">Hi,<div><br></div><div> I had couple of queries as below :</div><div><br></div><div><div dir="ltr" class="gmail_attr">On Thu, May 16, 2019 at 2:17 AM Muhammad Usama <<a href="mailto:m.usama@gmail.com" target="_blank">m.usama@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div dir="ltr"><div dir="ltr"><br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, May 10, 2019 at 6:38 PM Lakshmi Raghavendra <<a href="mailto:lakshmiym108@gmail.com" target="_blank">lakshmiym108@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div dir="ltr"><div>Hi,</div><div>I am trying pgpool for automatic faliover on my postgresql cluster using the watchdog feature</div><div>Wanted to know a couple of things </div><div>1. Are there any hooks when pgpool re-elects next pgpool master ? wanted to run some customization during this time</div></div></div></blockquote><div><font face="arial, sans-serif"><br></font></div><div><font face="arial, sans-serif">Pgpool executes the user provided commands at the time of acquiring and releasing of virtual IP by master pgpool node. You can</font></div><div><font face="arial, sans-serif">configure <span style="color:rgb(0,0,0)">wd_escalation_command and </span><span style="color:rgb(0,0,0)">wd_de_escalation_command</span> configuration parameters to provide the custom command or script.</font></div><div><font face="arial, sans-serif">Pgpool which executed <span style="color:rgb(0,0,0)">wd_escalation_command command </span>when it gets elected as a master and performs the escalation</font></div><div><font face="arial, sans-serif">and similarly when the it node will resign as a master the <span style="color:rgb(0,0,0)">wd_de_escalation_command command gets executed,</span></font></div></div></div></div></blockquote><div><br></div><div>1. I tried using the above <span style="color:rgb(0,0,0);font-family:arial,sans-serif">wd_escalation_command</span><span style="color:rgb(0,0,0);font-family:arial,sans-serif"> and </span><span style="color:rgb(0,0,0);font-family:arial,sans-serif">wd_</span><span style="color:rgb(0,0,0);font-family:arial,sans-serif">de_</span><font color="#000000" face="arial, sans-serif">escalation_command. I have a 3 node cluster, Observed that the escalation command will be triggered if there are at least 2 nodes alive in the pgpool cluster.</font></div></div><div><font color="#000000" face="arial, sans-serif">If there is only master pgpool alive with no slave nodes, the command is never initiated. Is this behavior expected ?</font></div><div><font color="#000000" face="arial, sans-serif"><br></font></div><div><font color="#000000" face="arial, sans-serif">2. Wanted to understand the significance of VIP, Is there any issue caused if I dont use the VIP in a 3-node pgpool cluster.</font></div><div><font color="#000000" face="arial, sans-serif"><br></font></div><div><font color="#000000" face="arial, sans-serif">Please let me know.</font></div><div><font color="#000000" face="arial, sans-serif"><br></font></div><div><font color="#000000" face="arial, sans-serif">Thanks And Regards,</font></div><div><font color="#000000" face="arial, sans-serif"><br></font></div><div><font color="#000000" face="arial, sans-serif"> Lakshmi Y M</font></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, May 16, 2019 at 2:17 AM Muhammad Usama <<a href="mailto:m.usama@gmail.com" target="_blank">m.usama@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div dir="ltr"><div dir="ltr"><br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, May 10, 2019 at 6:38 PM Lakshmi Raghavendra <<a href="mailto:lakshmiym108@gmail.com" target="_blank">lakshmiym108@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div dir="ltr"><div>Hi,</div><div>I am trying pgpool for automatic faliover on my postgresql cluster using the watchdog feature</div><div>Wanted to know a couple of things </div><div>1. Are there any hooks when pgpool re-elects next pgpool master ? wanted to run some customization during this time</div></div></div></blockquote><div><font face="arial, sans-serif"><br></font></div><div><font face="arial, sans-serif">Pgpool executes the user provided commands at the time of acquiring and releasing of virtual IP by master pgpool node. You can</font></div><div><font face="arial, sans-serif">configure <span style="color:rgb(0,0,0)">wd_escalation_command and </span><span style="color:rgb(0,0,0)">wd_de_escalation_command</span> configuration parameters to provide the custom command or script.</font></div><div><font face="arial, sans-serif">Pgpool which executed <span style="color:rgb(0,0,0)">wd_escalation_command command </span>when it gets elected as a master and performs the escalation</font></div><div><font face="arial, sans-serif">and similarly when the it node will resign as a master the <span style="color:rgb(0,0,0)">wd_de_escalation_command command gets executed,</span></font></div><div><font face="arial, sans-serif"><span style="color:rgb(0,0,0)"><br></span></font></div><div><a href="http://www.pgpool.net/docs/latest/en/html/runtime-watchdog-config.html#CONFIG-WATCHDOG-ESCALATION-DE-ESCALATION" target="_blank">http://www.pgpool.net/docs/latest/en/html/runtime-watchdog-config.html#CONFIG-WATCHDOG-ESCALATION-DE-ESCALATION</a></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div dir="ltr"><div>2. Will the VIP get assigned ony if there are more than 1 node present in the pgpool cluster? I had 3 nodes where i had pgpool running. When the 1st and 2nd node's pgpool was shut i was expecting the 3rd node to acquire the VIP but it didn't happen. And if my understanding was right i was thinking of using the VIP in my database connection string (Since it will always be with pgpool master who can connect to my postgresql primary). Now if the 3rd node is not acquiring the VIP, i could not use it my connection string. Correct me if my understanding is wrong</div></div></div></blockquote><div><br></div><div>master pgpool only acquires the VIP when the quorum exists ( minimum 50% of nodes are reachable). This is done by Pgpool to guard against the split-brain syndrome, which could happen</div><div>otherwise in case of network partitioning. So if you have 3 Pgpool nodes configured than the VIP will only get assigned on master node when at-least 2 Pgpool nodes are alive and reachable.</div><div>but in case of 2 node configuration, only 1 node is required to ensure the quorum and in that case even if the single node is alive, it will get the VIP</div><div><br></div><div>Thanks</div><div>Best Regards </div><div>Muhammad Usama</div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div dir="ltr"><div><br></div><div><br></div><div>Thanks in advance</div><div><br></div><div> Lakshmi Y M</div></div></div>
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