Postgres-XC Wiki

Here's a list of candidate parameters in gtm.conf and long option for GTM, GTM-Standby and GTM-Proxy.

Option Description GTM GTM-Standby GTM-Proxy
my_nodename Node Name my_nodename(main.c) my_nodename(main.c) TDB(proxy_main.c)
my_host Own host to listen ListenAddresses(main.c) ListenAddresses(main.c) ListenAddresses(proxy_main.c)
my_port Own port to listen GTMPortNumber(main.c) GTMPortNumber(main.c) GTMProxyPortNumber(proxy_main.c)
destination_host Host to connect No GTM_ActiveAddress(standby_utils.c) GTMServerHost(proxy_main.c)
destination_port Port to connect No GTM_ActivePort(standby_utils.c) GTMServerPortNumber(proxy_main.c)
log_file Log file name GTMLogFile(main.c) GTMLogFile(main.c) GTMLogFile(proxy_main.c)
log_min_message Message to log Yes(elog.c?) Yes(elog.c?) Yes(elog.c?)
initial_gxid GXID value to begin ? No No
startup GTM ACT or SBY Yes(main.c?) Yes(main.c?) No
worker_thread Worker Threads for GTM-Proxy No No GTMProxyWorkerThreads(proxy_main.c)
err_reporter Command to report error to outside Yes Yes Yes
status_reader Command to collect cluster status Yes Yes Yes
err_wait_opt If wait for reconnect at failure No No Yes
err_wait_interval How long to wait (in sec) No No Yes
err_wait_count How many times to wait No No Yes
keepalives_idle See tcp_keepalive_time Yes Yes Yes
keepalives_interval See tcp_keepalive_intvl Yes Yes Yes
keepalives_count See tcp_keepalive_probes Yes Yes yes

Further description is as follows:

  • GTM may be allowed to have destination_host and desitnation_port to specify connection point used at the time of switchover.
  • I'm not sure if initial_gxid should appear in gtm.conf because this is needed only at the the first time or when GTM restarts after crash, where restart GXID value is not reliable. I'm thinking to leave this in the command option.
  • err_reporter and status_reader is an external command to report any error or to obtain global XC cluster status respectively. It is supposed that they are a part of XCM module. Because they are not called frequently, it would be better not to include XCM libaries in GTM.
  • err_wait_opt, err_wait_interval and err_wait_count control the behavior of GTM-Proxy when it detects errors in send/receive data with GTM. This is needed to wait for "reconnect" operation when GTM fails.