On 01/31/2018 09:51 PM, Jan Wieck wrote:
> 
> 
> On Wed, Jan 31, 2018 at 12:32 PM, Stefan Blanke
> <stefan.bla...@framestore.com <mailto:stefan.bla...@framestore.com>> wrote:
> 
>     >
>     > I'll bet you it's not that. It's quite unlikely that would fail with
>     > exactly 1GB request size. It seems much more like a buffer that we keep
>     > to be power of 2. The question is which one.
> 
>     I had dismissed corruption before writing in. It's exactly 1GB every
>     time this has happened - and we can dump the full dataset
>     periodically without issue.
> 
>     >> I have my money on a corrupted TOAST entry. Is this happening on
>     >> trustworthy hardware or beige box with no ECC or RAID?
> 
>     It's good quality commercial hardware in our colo - no exactly sure
>     what.
> 
> 
> If it is a sporadic issue and you can dump the full dataset, then I just
> lost my money (Tomas, you coming to PGConf in Jersey City?).
> 

Unfortunately no, but I'm sure there will be other opportunities to buy
me a beer ;-) Like pgcon, for example.

>
> But then, if this is a plain COPY to stdout ... I am wondering what
> could possibly be in that path that wants to allocate 1GB. Or is this
> not so plain but rather a COPY ... SELECT ...?
> 

That's what I've been guessing, and why I was asking for a query plan.


regards

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

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