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List:       postgis-devel
Subject:    Re: [postgis-devel] MSSQL Serialization
From:       Mark Cave-Ayland <mark.cave-ayland () ilande ! co ! uk>
Date:       2016-01-22 14:08:15
Message-ID: 56A237CF.6070202 () ilande ! co ! uk
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On 21/01/16 22:49, Paul Ramsey wrote:

> Dan found this
> link https://msdn.microsoft.com/en-us/library/ee301648(v=sql.105).aspx
> 
> It's really interesting, I wish I could ask them questions :) 
> Some good use of flagging to keep things like points small. We come out
> slightly larger, I think, because of padding to keep the coordinates
> double aligned.
> They do not appear to bother with alignment. Maybe because they expect
> to always be on x86 architectures and others that don't fault on
> unaligned access? Though there's still a (theoretical) performance
> penalty to unaligned access even on x86.

Yeah that's an interesting read :)  These days the world is getting less
x86 and in just about every test I've done there is significant
performance improvement with aligned vs. unaligned accesses. For this
reason I'd expect PostGIS to perform better on high CPU, large geometry
processing but then there are plenty of other factors e.g. caching that
could also come into play here.


ATB,

Mark.

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