[pgpool-hackers: 3474] Proposal: health check statistics

[Tatsuo Ishii]

Currently Pgpool-II's health check process logs various information
including backend connection problem, retrying to recover from it, and
so on. This information is very important for users because it reports
the healthiness problem of PostgreSQL.　For example, observing
increase of retry count may suggest that network connection between
Pgpool-II and PostgreSQL having trouble so that users could replace
the switch before actual failure occurs. Problem is, it is annoying to
look for such that information from log files afterward since it may
already disappear or was not logged by other problems (such as disk
full).

I would like to propose a new feature:

- Accumulate health check statistics on shared memory so that later on
  users can look into the stats using PCP commands.

- Such statistics includes:
  - failure count per backend nodes
  - retry count per backend nodes
  - success count after retries

Comments and suggestions are welcome.

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp