Re: amount of WAL logs larger than expected

On Mon, May 9, 2016 at 11:23 AM, Mark Steben <mark(dot)steben(at)drivedominion(dot)com>
wrote:

> We run postgres 9.2.12 and run vacuum on a 540GB database.
>
> I've attached a 'show all' for your reference. With CHECkPOINT_SEGMENTS
> set at 128
> and CHECKPOINT_COMPLETION_TARGET set at 0.9 I wouldn't expect the number
> of logs in pg_xlog to creep much over 400. But when we run vacuum, the
> number can climb to over 5000 and threatens to blow out on space. Is there
> something else I should be looking at causing this unexpected number of
> logs?
>
> Our server is also master for a slony1.2.2.3 slave and also to a hot
> standby server.
>
>
Is the hot standby in a different network or over the WAN? Have you checked
for bandwidth saturation? Also, have a look at the directory the hot
standby is receiving WALs at, check if they most recent ones have a current
timestamp. If the WALs that are arriving have much older timestamps than
what is being generated on the primary, that could indicate slow transfer.
For example, I had an issue recently where 4k WALs built up on the primary
during a large ETL process. It took a few hours to ship those (compressed)
WALs over the WAN to the replica's data centre.