Re: version upgrade

On 9/1/2004 10:29 AM, Joe Conway wrote:

> Jeff wrote:
>> 
>> On Aug 31, 2004, at 6:30 PM, Josh Berkus wrote:
>>> Huh?    You can replicate onto the same server.    Kicks your 
>>> performance in
>>> the teeth but it works fine.   Heck, I did it on my laptop as a demo.
>> 
>> Doesn't work If you have say, a 100GB db and only 50GB free space.
>> Not nearly enough to duplicate. But plenty of breathing room for normal 
>> operation.
>> 
>> Various db's support in place upgrades. and I'm thankful I tried 
>> Informix's out on a test db first because it simply scribbled over all 
>> the data instead of upgrading. Support told me that can happen 
>> sometimes.  COOL HUH?
> 
> I think that's an incredibly important point, i.e., even if you want to 
> do an "in place" upgrade, you ought to be testing it out first on a 
> *full* copy of your production database. IMHO, anything less than a full 
> test is playing fast-and-loose with your data. This in turn implies that 
> you need enough space for a full replica anyway, so why not use slony?

Which is another point I was about to ask. How do these people, running 
those huge and horribly important databases, ever test a single 
application change? Or any schema changes for that matter. Do they 
really type "psql -c 'alter table ...' proddb" and believe they are 
professional users because they know what they are doing?

And don't tell me "we have a backup, so we could ...". That would mean 
that you can afford the downtime in the first place.


Jan

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