<div dir="ltr"><div>Out of interest I quickly checked whether the conclusions still hold for PostGIS2.2.<br>The changes made in ST_Clip, and some other functions including st_value seem to have altered not just the absolute timing (much faster) but also the relative timing of operations as a function of tile size.<br>
Point on raster overlays are now slower when tile size is small (<50 pixels), whereas previously there was an almost linear increase with tile size. Bborie may be able to explain why this change has occurred. I will try to add an update to the weblog at some point in order to clarify the sitation. It is GOOD NEWS as apparently there is now a single optimum tile size for both polygon and point overlays and this does seem to lie at around 200 - 300 pixels using the same example as the weblog, although I have not run enough tests to confirm this. I'll try to find time to confirm this.<br>
<br></div><div>Duncan<br><br></div><div><br>
<br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Thu, Sep 19, 2013 at 10:36 AM, Pierre Racine <span dir="ltr"><<a href="mailto:Pierre.Racine@sbf.ulaval.ca" target="_blank">Pierre.Racine@sbf.ulaval.ca</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">You can also have a look at this article from Duncan Golicher if you are doing raster/vector analysis:<br>
<br>
<a href="http://duncanjg.wordpress.com/2012/10/30/tile-size-for-raster-vector-overlays-in-postgis/" target="_blank">http://duncanjg.wordpress.com/2012/10/30/tile-size-for-raster-vector-overlays-in-postgis/</a><br>
<div><div class="h5"><br>
> -----Original Message-----<br>
> From: <a href="mailto:postgis-users-bounces@lists.osgeo.org">postgis-users-bounces@lists.osgeo.org</a> [mailto:<a href="mailto:postgis-users-">postgis-users-</a><br>
> <a href="mailto:bounces@lists.osgeo.org">bounces@lists.osgeo.org</a>] On Behalf Of Stephen Crawford<br>
> Sent: Friday, September 13, 2013 12:34 PM<br>
> To: <a href="mailto:postgis-users@lists.osgeo.org">postgis-users@lists.osgeo.org</a><br>
> Subject: Re: [postgis-users] tile size<br>
><br>
> OK, thanks. I will give that a try.<br>
><br>
><br>
><br>
> On 9/13/2013 12:31 PM, Adam Eskreis wrote:<br>
><br>
><br>
> The most common tile size that I've seen in production is 256x256<br>
><br>
><br>
> On Fri, Sep 13, 2013 at 10:33 AM, Bborie Park<br>
> <<a href="mailto:dustymugs@gmail.com">dustymugs@gmail.com</a>> wrote:<br>
><br>
><br>
> Steve,<br>
><br>
> There really isn't. What I do recommend is that if your raster<br>
> data is not going to change over time (and you don't need to replicate the<br>
> database), load them as out-db rasters. That way, you can easily change tile<br>
> size within the database with ST_Tile.<br>
><br>
><br>
><br>
> -bborie<br>
><br>
><br>
> On Fri, Sep 13, 2013 at 6:06 AM, Stephen Crawford<br>
> <<a href="mailto:src176@psu.edu">src176@psu.edu</a>> wrote:<br>
><br>
><br>
> Hi All,<br>
><br>
> Is there a rule of thumb for determining the best tile<br>
> size when tiling a raster?<br>
><br>
> Thanks,<br>
> Steve<br>
><br>
><br>
> --<br>
> Stephen Crawford<br>
> Center for Environmental Informatics<br>
> The Pennsylvania State University<br>
</div></div>> <tel:814.865.9905><br>
<div class="im HOEnZb">><br>
><br>
><br>
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</div><div class="im HOEnZb">> _______________________________________________<br>
> postgis-users mailing list<br>
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><br>
><br>
> --<br>
> Stephen Crawford<br>
> Center for Environmental Informatics<br>
> The Pennsylvania State University<br>
> <a href="mailto:src176@psu.edu">src176@psu.edu</a><br>
> 814.865.9905<br>
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</div></div></blockquote></div><br><br clear="all"><br>-- <br>Dr Duncan Golicher<br>Investigador Titular, <br>El Colegio de la Frontera Sur, Chiapas,Mexico<br>Mexico tel +52 1 967 137 94 20<br>Skype name duncangolicher<br>
<br>Publications: <a href="http://www.mendeley.com/profiles/duncan-golicher" target="_blank">http://www.mendeley.com/profiles/duncan-golicher</a><br><br>Senior lecturer, Bournemouth University, UK<br>Centre for Conservation Ecology & Environmental Change<br>
School of Applied Sciences<br>Christchurch House rm C218a<br>Bournemouth University<br>Fern Barrow<br>Poole (Dorset) BH12 5BB UK<br>Tel. +44 (0)1202 961682<br><br>For list of publications see Researcher ID:<br><a href="http://www.researcherid.com/rid/B-4240-2009" target="_blank">http://www.researcherid.com/rid/B-4240-2009</a><br>
<br><a href="mailto:dgolicher@bournemouth.ac.uk" target="_blank">dgolicher@bournemouth.ac.uk</a><br><a href="mailto:dgoliche@ecosur.mx" target="_blank">dgoliche@ecosur.mx</a><br><br>Researcher ID:<br><a href="http://www.researcherid.com/rid/B-4240-2009" target="_blank">http://www.researcherid.com/rid/B-4240-2009</a><br>
</div>