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Re: Range Types - typo + NULL string constructor

From: Jeff Davis <pgsql(at)j-davis(dot)com>
To: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
Cc: Alexander Korotkov <aekorotkov(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Range Types - typo + NULL string constructor
Date: 2011-10-31 18:01:44
Message-ID: 1320084104.4647.15.camel@jdavis (view raw or flat)
Thread:
Lists: pgsql-hackers
On Mon, 2011-10-24 at 13:15 +0300, Heikki Linnakangas wrote:
> >> * range_constructor_internal - I think it would be better to move logic
> >> to figure out the the arguments into the callers.
> >
> > Done.
> 
> The comment above range_constructor0() is now outdated.

Removed.

> >> * The gist support functions frequently call range_deserialize(), which
> >> does catalog lookups. Isn't that horrendously expensive?
> >
> > Yes, it was. I have introduced a cached structure that avoids syscache
> > lookups when it's the same range as the last lookup (the common case).
> 
> Hmm, I don't think that's safe. After Oid wraparound, a range type oid 
> might get reused for some other range type, and the cache would return 
> stale values. Extremely unlikely to happen by accident, but could be 
> exploited by an attacker.

Done.

> Ok. The name "canonical" certainly hints at that, but it would be good 
> to explicitly state that guideline. As the text stands, it would seem 
> that a canonical function that maps "[1,7]" to "[1,8)", and also vice 
> versa, "[1,8)" to "[1,7]", would be valid. That would be pretty silly, 
> but it would be good to say something like "The canonical output for two 
> values that are equal, like [1,7] and [1,8), must be equal. It doesn't 
> matter which representation you choose to be the canonical one, as long 
> as two equal values with different formattings are always mapped to the 
> same value with same formatting"

Used your wording, thank you.

Regards,
	Jeff Davis

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