Re: Prototype: In-place upgrade v02

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
Cc: Zdenek Kotala <Zdenek(dot)Kotala(at)Sun(dot)COM>, Bruce Momjian <bruce(at)momjian(dot)us>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Prototype: In-place upgrade v02
Date: 2008-09-08 12:30:59
Message-ID: 12664.1220877059@sss.pgh.pa.us
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Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> writes:
> The bpchar_pattern_ops change you mentioned must be this one:
>> A not-immediately-obvious incompatibility is that the sort order within
>> bpchar_pattern_ops indexes changes --- it had been identical to plain
>> strcmp, but is now trailing-blank-insensitive. This will impact
>> in-place upgrades, if those ever happen.

Yup.

> The way I read that, bpchar_pattern_ops just became less sensitive. Some
> values are now considered equal that weren't before, and thus can now be
> stored in any order. That's not an incompatible change, right?

No, consider 'abc^I' vs 'abc ' (^I denoting a tab character). These are
unequal in either case, but the sort order has flipped.

regards, tom lane

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