Re: database corruption questions

On 10/18/2012 01:06 AM, Daniel Serodio wrote:
> Craig Ringer wrote:
>> On 10/14/2012 05:53 AM, Heine Ferreira wrote:
>>> Hi
>>>
>>> Are there any best practices for avoiding database
>>> corruption?
>>
>> * Maintain rolling backups with proper ageing. For example, keep one a
>> day for the last 7 days, then one a week for the last 4 weeks, then
>> one a month for the rest of the year, then one a year.
> What kind of "rolling backups"? From pg_basebackup?

I'd recommend good old `pg_dump`, that way you're not assuming that your
cluster's on-disk format is intact and happy. Regular dumps will also
help detect any damage that might've crept in from file system
corruption, HDD/RAID faults, etc. Not that that should happen, but we're
talking preventative action here.

I elaborated somewhat here:

http://blog.ringerc.id.au/2012/10/avoiding-postgresql-database-corruption.html

Alternately, check out barman: http://www.pgbarman.org/ . I haven't
tried it yet, but it looks very promising. I'd still want to take
periodic dumps, as I'm reluctant to rely on `pg_basebackup` style
cluster copies alone.

>> * Keep up to date with the latest PostgreSQL patch releases. Don't be one of those people still running 9.0.0 when 9.0.10 is out.
> The problem is that updating the database usually results in downtime. Or can the downtime be avoided in a replication scenario?

Patches within the same minor release require extremely minimal downtime.

- Stop server
- Install new binaries
- Start server

How much downtime will a data corruption bug (yes, they've happened)
that's fixed in a new version cost you if you don't patch and it bites
you? Or a bug that causes a server crash and restart? Plan downtime, so
you don't have potentially much longer unplanned downtime at the worst
possible time.

You can do zero-downtime minor updates using hot standby and standby
promotion; see http://www.repmgr.org/ .

Updating to a new major release is a bigger job, but that's not what I'm
talking about.

BTW, please trim your replies to quote just the relevant context.

--
Craig Ringer