Re: Patch: Implement failover on libpq connect level.

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От	Mithun Cy
Тема	Re: Patch: Implement failover on libpq connect level.
Дата	16 ноября 2016 г. 07:32:01
Msg-id	CAD__OujrhLNB6QtWLxZtvJt5n=gT+waWtRMLSLk=7J+fiOAFqg@mail.gmail.com обсуждение исходный текст
Ответ на	Re: Patch: Implement failover on libpq connect level. (Robert Haas <robertmhaas@gmail.com>)
Ответы	Re: Patch: Implement failover on libpq connect level. Re: Patch: Implement failover on libpq connect level. Re: Patch: Implement failover on libpq connect level.
Список	pgsql-hackers

> So I am tempted to just
> hold my nose and hard-code the SQL as JDBC is presumably already
doing.

JDBC is sending "show transaction_read_only" to find whether it is master or not.

Victor's patch also started with it, but later it was transformed into pg_is_in_recovery

by him as it appeared more appropriate to identify the master / slave.

ConnectionFactoryImpl.java:685

+ private boolean isMaster(QueryExecutor queryExecutor, Logger logger)

+ throws SQLException, IOException {

+ byte[][] results = SetupQueryRunner.run(queryExecutor, "show transaction_read_only", true);

+ String value = queryExecutor.getEncoding().decode(results[0]);

+ return value.equalsIgnoreCase("off");

}

Thanks and Regards

Mithun C Y

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