pg_autoctl perform promotion¶
pg_autoctl perform promotion - Perform a failover that promotes a target node
Synopsis¶
This command starts a Postgres failover orchestration from the pg_auto_promotion monitor and targets given node:
usage: pg_autoctl perform promotion [ --pgdata --formation --group ]
--pgdata path to data directory
--formation formation to target, defaults to 'default'
--name node name to target, defaults to current node
--wait how many seconds to wait, default to 60
Description¶
The pg_auto_promotion monitor can be used to orchestrate a manual promotion, sometimes also known as a switchover. When doing so, split-brain are prevented thanks to intermediary states being used in the Finite State Machine.
The pg_autoctl perform promotion command waits until the promotion is
known complete on the monitor, or until the hard-coded 60s timeout has
passed.
The promotion orchestration is done in the background by the monitor, so even
if the pg_autoctl perform promotion stops on the timeout, the promotion
orchestration continues at the monitor.
Options¶
- --pgdata
Location of the Postgres node being managed locally. Defaults to the environment variable
PGDATA. Use--monitorto connect to a monitor from anywhere, rather than the monitor URI used by a local Postgres node managed withpg_autoctl.- --formation
Formation to target for the operation. Defaults to
default.- --name
Name of the node that should be elected as the new primary node.
- --wait
How many seconds to wait for notifications about the promotion. The command stops when the promotion is finished (a node is primary), or when the timeout has elapsed, whichever comes first. The value 0 (zero) disables the timeout and allows the command to wait forever.
Environment¶
PGDATA
Postgres directory location. Can be used instead of the
--pgdataoption.
PG_AUTOCTL_MONITOR
Postgres URI to connect to the monitor node, can be used instead of the
--monitoroption.
PG_CONFIG
Can be set to the absolute path to the pg_config Postgres tool. This is mostly used in the context of building extensions, though it can be a useful way to select a Postgres version when several are installed on the same system.
PATH
Used the usual way mostly. Some entries that are searched in the PATH by the
pg_autoctlcommand are expected to be found only once, to avoid mistakes with Postgres major versions.
PGHOST, PGPORT, PGDATABASE, PGUSER, PGCONNECT_TIMEOUT, …
See the Postgres docs about Environment Variables for details.
TMPDIR
The pgcopydb command creates all its work files and directories in
${TMPDIR}/pgcopydb, and defaults to/tmp/pgcopydb.
XDG_CONFIG_HOME
The pg_autoctl command stores its configuration files in the standard place XDG_CONFIG_HOME. See the XDG Base Directory Specification.
XDG_DATA_HOME
The pg_autoctl command stores its internal states files in the standard place XDG_DATA_HOME, which defaults to
~/.local/share. See the XDG Base Directory Specification.
Examples¶
$ pg_autoctl show state
Name | Node | Host:Port | LSN | Connection | Current State | Assigned State
------+-------+----------------+-----------+--------------+---------------------+--------------------
node1 | 1 | localhost:5501 | 0/4000F88 | read-only | secondary | secondary
node2 | 2 | localhost:5502 | 0/4000F88 | read-write | primary | primary
node3 | 3 | localhost:5503 | 0/4000F88 | read-only | secondary | secondary
$ pg_autoctl perform promotion --name node1
13:08:13 15297 INFO Listening monitor notifications about state changes in formation "default" and group 0
13:08:13 15297 INFO Following table displays times when notifications are received
Time | Name | Node | Host:Port | Current State | Assigned State
---------+-------+-------+----------------+---------------------+--------------------
13:08:13 | node1 | 0/1 | localhost:5501 | secondary | secondary
13:08:13 | node2 | 0/2 | localhost:5502 | primary | draining
13:08:13 | node2 | 0/2 | localhost:5502 | draining | draining
13:08:13 | node1 | 0/1 | localhost:5501 | secondary | report_lsn
13:08:13 | node3 | 0/3 | localhost:5503 | secondary | report_lsn
13:08:19 | node3 | 0/3 | localhost:5503 | report_lsn | report_lsn
13:08:19 | node1 | 0/1 | localhost:5501 | report_lsn | report_lsn
13:08:19 | node1 | 0/1 | localhost:5501 | report_lsn | prepare_promotion
13:08:19 | node1 | 0/1 | localhost:5501 | prepare_promotion | prepare_promotion
13:08:19 | node1 | 0/1 | localhost:5501 | prepare_promotion | stop_replication
13:08:19 | node2 | 0/2 | localhost:5502 | draining | demote_timeout
13:08:19 | node3 | 0/3 | localhost:5503 | report_lsn | join_secondary
13:08:19 | node2 | 0/2 | localhost:5502 | demote_timeout | demote_timeout
13:08:19 | node3 | 0/3 | localhost:5503 | join_secondary | join_secondary
13:08:20 | node1 | 0/1 | localhost:5501 | stop_replication | stop_replication
13:08:20 | node1 | 0/1 | localhost:5501 | stop_replication | wait_primary
13:08:20 | node2 | 0/2 | localhost:5502 | demote_timeout | demoted
13:08:20 | node1 | 0/1 | localhost:5501 | wait_primary | wait_primary
13:08:20 | node3 | 0/3 | localhost:5503 | join_secondary | secondary
13:08:20 | node2 | 0/2 | localhost:5502 | demoted | demoted
13:08:20 | node2 | 0/2 | localhost:5502 | demoted | catchingup
13:08:21 | node3 | 0/3 | localhost:5503 | secondary | secondary
13:08:21 | node1 | 0/1 | localhost:5501 | wait_primary | primary
13:08:21 | node2 | 0/2 | localhost:5502 | catchingup | catchingup
13:08:21 | node1 | 0/1 | localhost:5501 | primary | primary
$ pg_autoctl show state
Name | Node | Host:Port | LSN | Connection | Current State | Assigned State
------+-------+----------------+-----------+--------------+---------------------+--------------------
node1 | 1 | localhost:5501 | 0/40012F0 | read-write | primary | primary
node2 | 2 | localhost:5502 | 0/40012F0 | read-only | secondary | secondary
node3 | 3 | localhost:5503 | 0/40012F0 | read-only | secondary | secondary