From: | Mark Cave-Ayland <mark(dot)cave-ayland(at)siriusit(dot)co(dot)uk> |
---|---|
To: | Anton Belyaev <anton(dot)belyaev(at)gmail(dot)com> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: R-tree, order by, limit |
Date: | 2008-09-22 11:45:15 |
Message-ID: | 48D7854B.1000502@siriusit.co.uk |
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Lists: | pgsql-general |
Anton Belyaev wrote:
> Mark, thanks for the suggestion.
> I examined PostGIS some time ago. It is too complex for my simple task
> and it gives no advantages for me:
Well okay but bear in mind the PostGIS is the de-facto standard for most
open source GIS tools. Programs like QGIS et al can visualise the
content of PostGIS tables just by pointing it towards the relevant
database - the in-built PostgreSQL geometry types aren't supported by
anything as far as I know. And don't forget coordinate re-projection -
PostGIS also allows you to re-project between latitude/longitude and
local map spatial reference systems on the fly.
> For spatial indexing it uses the same GiST-based R-tree.
Not quite. The PostGIS indexes have been improved to include selectivity
functions to allow the planner to determine when it should use the
spatial index. AFAIK the in-built PostgreSQL types use fixed values, so
the choice of index usage will be incredibly naive and often wrong on
larger datasets mixing spatial and non-spatial columns as part of the
search query.
> And PostGIS does not offer that "population" or "priority" queries I need.
Maybe. But you may find the wiki at
http://postgis.refractions.net/support/wiki/ is a good starting point
for code examples.
ATB,
Mark.
--
Mark Cave-Ayland
Sirius Corporation - The Open Source Experts
http://www.siriusit.co.uk
T: +44 870 608 0063
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