[pgpool-general: 9216] Re: Load balancing of write queries among health-checked nodes

[Tatsuo Ishii]

>>> One downside of the configuration is, if pgpool-A goes down, client-A
>>> cannot send queries to pgpool-A. client-A has to switch the connection
>>> to pgpool-B or pgpool-C if it wants to continue processing.
>> To mitigate the problem, you could specify multiple host in your
>> client. i.e.:
>> psql "host=A,B port=9999,9999 dbname=test" for client-A. This will try
>> A first but if A is down, it will try B next.
> 
> Will libpq just test connectivity with the Pgpool instances,

Yes.

> or it may
> test whether the Pgpool instance is detached from the cluster? Of
> course libpq doesn't know about Pgpool, it just uses the PostgreSQL
> protocol, but in case of a detached Pgpool instance will an SQL
> statement fail with such an error message so that libpq will try the
> next host?

What do you mean by "detached Pgpool instance"? It is possible to
detach PostgreSQL instance from pgpool but there's no such an
operation to detach pgpool.

Best reagards,
--
Tatsuo Ishii
SRA OSS K.K.
English: http://www.sraoss.co.jp/index_en/
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