[postgis-users] Any native compression strategies suited for a revisioning system?

[Peter Devoy]

Hi Nicklas

Just read the spec. of TWKB and it sounds very promising.  Great
recommendation, many thanks for your help.

Kind regards


Peter

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On 13 December 2015 at 16:55, nicklas.aven <nicklas.aven at jordogskog.no>
wrote:

> Hi
>
> You could take a look at the twkb format. There is encoder (ST_AsTWKB) and
> decoder (ST_GeomFromTWKB) in PostGIS since version 2.2. Twkb can be stored
> as bytea in the database.
>
> HTH
> Nicklas Avén
>
>
>
> Sent from my Samsung device
>
>
> -------- Original message --------
> From: Peter Devoy <peter at 3xe.co.uk>
> Date: 13/12/2015 15:47 (GMT+01:00)
> To: postgis-users at lists.osgeo.org
> Subject: [postgis-users] Any native compression strategies suited for a
> revisioning system?
>
> I have been tasked with creating a revisioning system for geometries
> stored by PostGIS.  To avoid data duplication I thought about storing
> only diffs but because that introduces other complications I am
> thinking about just storing each revision in its entirety and having a
> compression mechanism minimize size on disk.
>
> However, it seems to me that, quite rightly, Postgres's compression
> algorithm (PGLZ?) is not optimised for delta encoding or high
> compression ratios.  So are there any options short of me implementing
> user-defined functions to wrap a compression library?
>
> For clarity, with this method I am thinking each geometry would have a
> corresponding row in which a field would hold all revisions in a JSON
> data structure.
>
>
> Peter
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>
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