Re: revised hstore patch

From: "David E(dot) Wheeler" <david(at)kineticode(dot)com>
To: Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk>
Cc: tgl(at)sss(dot)pgh(dot)pa(dot)us (Tom Lane), pgsql-hackers(at)postgresql(dot)org
Subject: Re: revised hstore patch
Date: 2009-07-22 16:13:39
Message-ID: 8C8011AE-D3A9-426E-81A5-0752BCE7BD01@kineticode.com
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On Jul 22, 2009, at 8:55 AM, Andrew Gierth wrote:

> The other option would be to fix the wasted-space bug in the existing
> hstore, and document that stored data must be updated at least once
> subsequent to that fix before doing a binary migrate to 8.5.

Given this…

> (The pathological case is _very_ rare, requiring an 0-length key with
> exactly 32kb of data, followed by a specific series of key lengths
> with values of length 1, and with more than 28kbytes of wasted space
> at the end of the value, and only on little-endian machines. The only
> way to get that much wasted space is to do several thousand iterations
> of UPDATE ... SET hs = hs || ''; each of which adds 8 bytes of wasted
> space to the end of the value. But even so, somebody, somewhere,
> probably has a value that matches...)

Could it be that only folks with such a manifestation of the bug would
need to do a binary upgrade? If so, I certainly think it'd be worth it
to fix the bug.

Best,

David

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