Provided by: pgpool2_4.3.7-1ubuntu4_amd64 
NAME
SHOW_POOL_HEALTH_CHECK_STATS - show health check statistics data
SYNOPSIS
SHOW POOL_HEALTH_CHECK_STATS
DESCRIPTION
SHOW POOL_HEALTH_CHECK_STATS displays health check (see Section 5.8, “Health Check”, in the
documentation) statistic data mostly collected by health check process. This command helps Pgpool-II
admin to study events related to health check. For example, admin can easily locate the failover event in
the log file by looking at "last_failed_health_check" column. Another example is finding unstable
connection to backend by evaluating "average_retry_count" column. If particular node shows higher retry
count than other node, there may be problem to the connection to the backend.
Table 27, “Statistics data shown by pool_health_check_stats command” shows each column name and its
description.
Table 27. Statistics data shown by pool_health_check_stats command
┌──────────────────────────────┬───────────────────────────────────────┐
│ Column Name │ Description │
├──────────────────────────────┼───────────────────────────────────────┤
│ node_id │ Backend node id. │
├──────────────────────────────┼───────────────────────────────────────┤
│ hostname │ Backend hostname or UNIX domain │
│ │ socket path. │
├──────────────────────────────┼───────────────────────────────────────┤
│ port │ Backend port number. │
├──────────────────────────────┼───────────────────────────────────────┤
│ status │ Backend status. One of up, down, │
│ │ waiting, unused or quarantine. │
├──────────────────────────────┼───────────────────────────────────────┤
│ role │ Role of the node. Either primary or │
│ │ standby in streaming │
│ │ replication mode. Either main │
│ │ or replica in other mode. │
├──────────────────────────────┼───────────────────────────────────────┤
│ last_status_change │ Timestamp of last backend status │
│ │ changed. │
├──────────────────────────────┼───────────────────────────────────────┤
│ total_count │ Number of health check count in │
│ │ total. │
├──────────────────────────────┼───────────────────────────────────────┤
│ success_count │ Number of successful health check │
│ │ count in total. │
├──────────────────────────────┼───────────────────────────────────────┤
│ fail_count │ Number of failed health check count │
│ │ in total. │
├──────────────────────────────┼───────────────────────────────────────┤
│ skip_count │ Number of skipped health check count │
│ │ in total. If the node is │
│ │ already down, health check │
│ │ skips the node. │
├──────────────────────────────┼───────────────────────────────────────┤
│ retry_count │ Number of retried health check count │
│ │ in total. │
├──────────────────────────────┼───────────────────────────────────────┤
│ average_retry_count │ Number of average retried health │
│ │ check count in a health check │
│ │ session. │
├──────────────────────────────┼───────────────────────────────────────┤
│ max_retry_count │ Number of maximum retried health │
│ │ check count in a health check │
│ │ session. │
├──────────────────────────────┼───────────────────────────────────────┤
│ max_duration │ Maximum health check duration in │
│ │ Millie seconds. If a health │
│ │ check session retries, the │
│ │ health check duration is sum of each │
│ │ retried health check. │
├──────────────────────────────┼───────────────────────────────────────┤
│ min_duration │ Minimum health check duration in │
│ │ Millie seconds. If a health │
│ │ check session retries, the │
│ │ health check duration is sum of each │
│ │ retried health check. │
├──────────────────────────────┼───────────────────────────────────────┤
│ average_duration │ Average health check duration in │
│ │ Millie seconds. If a health │
│ │ check session retries, the │
│ │ health check duration is sum of each │
│ │ retried health check. │
├──────────────────────────────┼───────────────────────────────────────┤
│ last_health_check │ Timestamp of last health check. If │
│ │ heath check does not │
│ │ performed yet, empty string. │
├──────────────────────────────┼───────────────────────────────────────┤
│ last_successful_health_check │ Timestamp of last successful health │
│ │ check. If heath check does │
│ │ not succeeds yet, empty │
│ │ string. │
├──────────────────────────────┼───────────────────────────────────────┤
│ last_skip_health_check │ Timestamp of last skipped health │
│ │ check. If heath check is not │
│ │ skipped yet, empty string. │
│ │ Note that it is possible that this │
│ │ field is an empty string even │
│ │ if the status is down. In this │
│ │ case failover was triggered by │
│ │ other than health check process. │
├──────────────────────────────┼───────────────────────────────────────┤
│ last_failed_health_check │ Timestamp of last failed health │
│ │ check. If heath check does not │
│ │ fail yet, empty string. Note │
│ │ that it is possible that this │
│ │ field is an empty string even │
│ │ if the status is down. In this │
│ │ case failover was triggered by │
│ │ other than health check process. │
└──────────────────────────────┴───────────────────────────────────────┘
Here is an example session:
test=# show pool_health_check_stats;
-[ RECORD 1 ]----------------+--------------------
node_id | 0
hostname | /tmp
port | 11002
status | up
role | primary
last_status_change | 2020-01-26 19:08:45
total_count | 27
success_count | 27
fail_count | 0
skip_count | 0
retry_count | 0
average_retry_count | 0.000000
max_retry_count | 0
max_duration | 9
min_duration | 2
average_duration | 6.296296
last_health_check | 2020-01-26 19:12:45
last_successful_health_check | 2020-01-26 19:12:45
last_skip_health_check |
last_failed_health_check |
-[ RECORD 2 ]----------------+--------------------
node_id | 1
hostname | /tmp
port | 11003
status | down
role | standby
last_status_change | 2020-01-26 19:11:48
total_count | 19
success_count | 12
fail_count | 1
skip_count | 6
retry_count | 3
average_retry_count | 0.230769
max_retry_count | 3
max_duration | 83003
min_duration | 0
average_duration | 6390.307692
last_health_check | 2020-01-26 19:12:48
last_successful_health_check | 2020-01-26 19:10:15
last_skip_health_check | 2020-01-26 19:12:48
last_failed_health_check | 2020-01-26 19:11:48
pgpool-II 4.3.7 2023 SHOW POOL_HEALTH_CHECK_STATS(1)