Log: "Error collecting replication statistics"

[joekohlsdorf]

Server version: 11.4 on RDS
Collector version: v0.21.0

The collector logs the following message:

Error collecting replication statistics: sql: Scan error on column index 11, name "write_lsn": unsupported Scan, storing driver.Value type <nil> into type *string

The only thing which might be a bit extraordinary might be that this server has active logical replication slots.
I'm happy to provide more information if necessary.

[lfittl]

Hi @joekohlsdorf - thanks for your patience on this!

This is likely a permission issue, but we should probably still ignore that error. Could you try if adding the following as an rds_superuser resolves it:

CREATE OR REPLACE FUNCTION pganalyze.get_stat_replication() RETURNS SETOF pg_stat_replication AS
$$
  /* pganalyze-collector */ SELECT * FROM pg_catalog.pg_stat_replication;
$$ LANGUAGE sql VOLATILE SECURITY DEFINER;

If it does not, could you send a sample of the output of SELECT * FROM pg_stat_replication? If you don't want to share it here feel free to open a support request instead via support@pganalyze.com

Thanks!

[joekohlsdorf]

I have verified that I already have this function defined and I can query it manually.

The output from SELECT pganalyze.get_stat_replication(); is:

(13311,16388,rdsrepladmin,walreceiver,10.1.1.178,,47446,"2019-07-23 00:51:21.073245-04",,streaming,19F8/AC467C00,19F8/AC467C00,19F8/AC467C00,19F8/AC467C00,00:00:00.002261,00:00:00.003447,00:00:00.00345,0,async)
(3561,16386,admin,"",172.30.50.249,,38515,"2019-07-23 21:18:25.434786-04",,streaming,19F8/AC467C00,,19F8/AC43CDB8,,,,,0,async)

This seems to be a similar case as #21
Only that in my case this is a logical replication slot so a lot more values are NULL.

[lfittl]

@joekohlsdorf Thanks, thats very helpful!

Fixed now in master, and will be in the next release (likely coming out next week).