Provided by: pgpool2_4.3.5-1_amd64 bug

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 25, “Statistics data shown by pool_health_check_stats command” shows each column
       name and its description.

       Table 25. Statistics data shown by pool_health_check_stats command
       ┌─────────────────────────────┬──────────────────────────────────┐
       │Column NameDescription                      │
       ├─────────────────────────────┼──────────────────────────────────┤
       │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