Re: strem replication standby lag check

> 2014/1/17 yhe <yinghe0101(at)yahoo(dot)com>
>> any way I can do that without a dblink?
>>

On Mon, Jan 20, 2014 at 4:33 AM, desmodemone <desmodemone(at)gmail(dot)com> wrote:
> I think it's better to use the pg_stat_replication

+1

And this is how to make all the calculation of the lag (in bytes):

CREATE OR REPLACE FUNCTION hex_to_int(i_hex text, OUT o_dec integer)
RETURNS integer LANGUAGE 'plpgsql' IMMUTABLE STRICT AS $$
BEGIN
EXECUTE 'SELECT x''' || i_hex || '''::integer' INTO o_dec;
RETURN;
END $$;

SELECT
client_addr,
sent_offset - (
replay_offset - (sent_xlog - replay_xlog) * 255 * 16 ^ 6 ) AS byte_lag
FROM (
SELECT
client_addr,
hex_to_int(split_part(sent_location, '/', 1)) AS sent_xlog,
hex_to_int(split_part(replay_location, '/', 1)) AS replay_xlog,
hex_to_int(split_part(sent_location, '/', 2)) AS sent_offset,
hex_to_int(split_part(replay_location, '/', 2)) AS replay_offset
FROM pg_stat_replication
) AS s;

--
Kind regards,
Sergey Konoplev
PostgreSQL Consultant and DBA

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