Scott Marlowe wrote:
> On Sat, May 9, 2015 at 11:20 PM, Albe Laurenz <laurenz.albe@wien.gv.at> wrote:
>> Maxim Boguk wrote:
>>> It's depend where a corruption happen, if pages become corrupted due to some
>>> problems with physical storage (filesystem) in that case a replica data should be ok.
>> I would not count on that.
>> I have had a case where a table file got corrupted due to hardware problems.
>> Pages that contained data were suddenly zeroed.
>> PostgreSQL recognizes such a block as empty, so the user got no error, but
>> data were suddenly missing. What does a user do in such a case? He/she grumbles
>> and enters the data again. This insert will be replicated to the standby (which was
>> fine up to then) and will cause data corruption there (duplicate primary keys).
> You had zero corrupted pages turned on. PostgreSQL by default does NOT
> DO THIS. That setting is for recovering a corrupted database not for
> everyday use!
No, I didn't.
It was not PostgreSQL that zeroed the page, but the hardware or operating system.
The problem was a flaky fibre channel cable that intermittently was connected and disconnected.
That corrupted the file system, and I guess it must have been file system recovery
that zeroed the pages. I'm not 100% certain, at any rate the symptoms were silently missing data.
Yours,
Laurenz Albe
