On Thursday 30 January 2003 18:39, Tom Lane wrote:
> Well, great; you're probably proof against misfeasance of your local
> power company.  But how about someone tripping over the power cord?


> Or a blowout in the server's internal power supply?

Redundant supplies.

>  Or a kernel crash?

Different from pulling the plug.

> It is faulty to equate the amount of testing required to gain confidence
> in that port with the amount of testing required to gain confidence that
> PG 7.4 will run reliably on, say, HPUX 10.20, when we already know that
> every PG back to 6.4 has run reliably on HPUX 10.20.

But does the fact that PG 6.4 ran reliably on HP-UX 10 mean PG 7.4 will run as 
reliably on HP-UX 11?  Does the fact that PG 6.2.1 ran well on Linux kernel 
2.0.30 with libc 5.3.12 mean PG 7.4 will run well on Linux 2.6.x with glibc 
2.4.x?  The OS is also a moving target.  Hmph.  PG 7.3 won't even build on 
Red Hat 5.2, for instance.  So much for track record.

>  You're attacking a
> straw man you have set up, namely the idea that only specific testing
> produces confidence in a port.  In my mind past track record has a lot
> more to do with confidence than whatever testing we do for an individual
> release.

Track record means nothing if sufficient items have changed in the underlying 
OS.  I remember the Linux fiasco with PostgreSQL 6.3.1.  It was so bad that 
Red Hat was considering releasing Red Hat 5.1 with a CVS checkout of 
pre-6.3.2.  That is not Red Hat's normal policy.

Also, between major versions enough may have changed to make it necessary to 
test thoroughly -- WAL, for instance.  MVCC for another instance.  PITR is 
going to be another instance requiring a different test methodology.  One 
will indeed be required to blow down the whole system to properly test PITR, 
on all platforms.

Track record indicates that all of our x.y.1 releases are typically hosed in 
some fashion.  7.3.1 proved that wrong.  Track record only requires a single 
failure to invalidate -- and we should test for those failures across the 
board, regardless of track record.  Records are meant to be broken.
Lamar Owen
WGCR Internet Radio
1 Peter 4:11

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