Thanks Rémi. They do indeed appear to be compressed using your two tests. And the improved SQL is about 20% faster. Thanks!
From: postgis-users-boun...@lists.osgeo.org [mailto:postgis-users-boun...@lists.osgeo.org] On Behalf Of Rémi Cura Sent: Thursday, March 26, 2015 8:37 PM To: PostGIS Users Discussion Subject: Re: [postgis-users] 2.1.6 Released Hum you can do a simple test, for the table you are using, look at the pgpoint column type number (called pcid) You can know this like this SELECT pc_astext(pt) FROM xyz_patches, pc_explode(pa) as pt LIMIT 1 Know look into public.pointcloud_formats, the xml schema corresponding to the pcid you found. You should see if it is compressed. Another method is to take a patch and compare it with the uncompressed version. SELECT block_id, pa, pc_uncompress(pa) FROM patches LIMIT 1 Here is the correct way to write your querry anyway, you should see a great speed up. --recent postgres SELECT block_id , pc_get(pt, 'X') as x, pc_get(pt, 'Y') as y, pc_get(pt, 'Z') as z FROM xyz_patches, pc_explode(pa) as pt --old postgres WITH points AS ( SELECT block_id, pc_explode(pa) as pt FROM xyz_patches, pc_explode(pa) as pt ) SELECT block_id , pc_get(pt, 'X') as x, pc_get(pt, 'Y') as y, pc_get(pt, 'Z') as z FROM points Cheers, Rémi-C 2015-03-26 19:09 GMT+01:00 Jonathan Moules <j.mou...@hrwallingford.com<mailto:j.mou...@hrwallingford.com>>: Hi Rémi, Thanks for the reply and information. I’m afraid I inherited this database and don’t know much about it (or pointcloud). Looking into though, I doubt it’s compressed, we extract the data with: select block_id , pc_get(pc_explode(pa), 'X') as x, pc_get(pc_explode(pa), 'Y') as y, pc_get(pc_explode(pa), 'Z') as z from xyz_patches so using pc_get rather than pc_uncompress. On the other hand, there are 6 entries in pointcloud_formats which all have the “<Metadata name="compression">dimensional</Metadata>” line set. But I can’t decipher the documentation well enough to know if the data actually uses it. Cheers, Jonathan From: postgis-users-boun...@lists.osgeo.org<mailto:postgis-users-boun...@lists.osgeo.org> [mailto:postgis-users-boun...@lists.osgeo.org<mailto:postgis-users-boun...@lists.osgeo.org>] On Behalf Of Rémi Cura Sent: Thursday, March 26, 2015 5:33 PM To: PostGIS Users Discussion Subject: Re: [postgis-users] 2.1.6 Released Hey, if you use the compression of patch and sensible xml schema, you should already have a 1:2 to 1:4 compression of the point size. (compared to binary ply in my case) Cheers, Rémi-C 2015-03-26 18:05 GMT+01:00 Jonathan Moules <j.mou...@hrwallingford.com<mailto:j.mou...@hrwallingford.com>>: Hi Paul, I suspect I know the answer to this (“no”), but to confirm, is the disk saving for points going to apply to points stored using the pointcloud extension in a postgis database? Thanks, Jonathan From: postgis-users-boun...@lists.osgeo.org<mailto:postgis-users-boun...@lists.osgeo.org> [mailto:postgis-users-boun...@lists.osgeo.org<mailto:postgis-users-boun...@lists.osgeo.org>] On Behalf Of Paul Ramsey Sent: Friday, March 20, 2015 5:45 PM To: PostGIS Users Discussion Subject: [postgis-users] 2.1.6 Released The 2.1.6 release of PostGIS is now available<http://download.osgeo.org/postgis/source/postgis-2.1.6.tar.gz>. The PostGIS development team is happy to release patch for PostGIS 2.1, the 2.1.6 release. As befits a patch release, the focus is on bugs, breakages, and performance issues. Users with large tables of points will want to priorize this patch, for substantial (~50%) disk space savings. http://download.osgeo.org/postgis/source/postgis-2.1.6.tar.gz Enhancements • #3000, Ensure edge splitting and healing algorithms use indexes • #3048, Speed up geometry simplification (J.Santana @ CartoDB) • #3050, Speep up geometry type reading (J.Santana @ CartoDB) Bug Fixes • #2941, allow geography columns with SRID other than 4326 • #3069, small objects getting inappropriately fluffed up w/ boxes • #3068, Have postgis_typmod_dims return NULL for unconstrained dims • #3061, Allow duplicate points in JSON, GML, GML ST_GeomFrom* functions • #3058, Fix ND-GiST picksplit method to split on the best plane • #3052, Make operators <-> and <#> available for PostgreSQL < 9.1 • #3045, Fix dimensionality confusion in &&& operator • #3016, Allow unregistering layers of corrupted topologies • #3015, Avoid exceptions from TopologySummary • #3020, ST_AddBand out-db bug where height using width value • #3031, Allow restore of Geometry(Point) tables dumped with empties in them View all closed tickets<http://trac.osgeo.org/postgis/query?status=closed&groupdesc=1&group=priority&milestone=PostGIS+2.1.6&order=priority>. -- Paul Ramsey http://cleverelephant.ca http://postgis.net This message has been scanned for viruses by MailControl<http://www.mailcontrol.com/>, a service from BlackSpider Technology Click here<https://www.mailcontrol.com/sr/MZbqvYs5QwJvpeaetUwhCQ==> to report this email as spam. ________________________________ HR Wallingford and its subsidiaries uses faxes and emails for confidential and legally privileged business communications. 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