Re: Checksum errors in pg_stat_database

On 1/11/19 7:40 PM, Robert Haas wrote:
> On Fri, Jan 11, 2019 at 5:21 AM Magnus Hagander <magnus@hagander.net> wrote:
>> Would it make sense to add a column to pg_stat_database showing
>> the total number of checksum errors that have occurred in a database?
>> 
>> It's really a ">1 means it's bad", but it's a lot easier to monitor
>> that in the statistics views, and given how much a lot of people
>> set their systems out to log, it's far too easy to miss individual
>> checksum matches in the logs.
>>
>> If we track it at the database level, I don't think the overhead 
>> of adding one more counter would be very high either.
> 
> It's probably not the idea way to track it.  If you have a terabyte or
> fifty of data, and you see that you have some checksum failures, good
> luck finding the offending blocks.
> 

Isn't that somewhat similar to deadlocks, which we also track in
pg_stat_database? The number of deadlocks is rather useless on it's own,
you need to dive into the server log to find the details. Same for
checksum errors.

> But I'm tentatively in favor of your proposal anyway, because it's
> pretty simple and cheap and might help people, and doing something
> noticeably better is probably annoyingly complicated.
> 

+1

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services