Re: Fixed length data types issue

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От Markus Schaber
Тема Re: Fixed length data types issue
Дата
Msg-id 45054F63.7010503@logix-tt.com
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Ответ на Re: Fixed length data types issue  (Tom Lane <tgl@sss.pgh.pa.us>)
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Hi, Tom,

Tom Lane wrote:

> The only way we could pack stuff without alignment is to go over to the
> idea that memory and disk representations are different --- where in
> this case the "conversion" might just be a memcpy to a known-aligned
> location.  The performance costs of that seem pretty daunting, however,
> especially when you reflect that simply stepping over a varlena field
> would require memcpy'ing its length word to someplace.

AFAICS, PostGIS already uses this approach internally, mostly because
its current format requires a mix of byte-sized and larger (int, double)
fields.

Markus


--
Markus Schaber | Logical Tracking&Tracing International AG
Dipl. Inf.     | Software Development GIS

Fight against software patents in EU! www.ffii.org www.nosoftwarepatents.org


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