I'm trying to hunt down what causes replication slots to go inactive. Might seem like a remedial question but I'm noticing that on my master database server, I have many inactive replication slots that are taking up some space on the disk. I know I can just drop inactive slots using the pg_drop_replication_slot(slot_name name) command.

But I'd also like to be able review how we are doing our work / code to see if we are doing something wrong.

If a child server goes offline... from what I've read, it's supposed to just reconnect to the same slot when it comes back up. So not too sure what causes a slot to go inactive.

Here's the query I'm running to see what's what:

widgets=# SELECT slot_name, database, active, pg_xlog_location_diff(pg_current_xlog_insert_location(), restart_lsn) AS retained_bytes
widgets-# FROM pg_replication_slots
widgets-# WHERE plugin = 'bdr';
        slot_name         | database | active | retained_bytes
 bdr_16385_12345_1_1111__ | widgets  | f      | 2431628304
 bdr_16385_11111_1_1638__ | widgets  | f      | 2432065824
 bdr_16385_22222_1_1638__ | widgets  | t      | 56
 bdr_16385_33333_1_2222__ | widgets  | t      | 56
 bdr_16385_44441_1_1111__ | widgets  | f      | 2432185336
 bdr_16385_55551_1_1111__ | widgets  | f      | 1133538200
 bdr_16385_66661_1_1111__ | widgets  | f      | 2431950952
 bdr_16385_77771_1_1111__ | widgets  | f      | 2432057320
 bdr_16385_88881_1_1111__ | widgets  | f      | 2331233432
(9 rows)


Any comments would be appreciated.

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