Hi Sergei! I moved this back to the mailing list, because of your .FRM explanation, and also because I'd like to explain rasters. A GIS raster is an array of data represented as a raster image. Rasters have "layers" and each layer can have a different measurement in it. It is most commonly used for height maps.
The pgsql schema that I sent you is for a personal project of mine that uses Voxel.js (http://voxeljs.com/) to turn real world height maps from the space shuttle (SRTM v3 data) into interpolated 1 meter resolution voxel (minecraft-like, as 1 block = 1 sq meter) landscapes. I intersect the raster data with the GIS data from OSM (open street map) so that I can render buildings, roads, forest areas, rivers, etc, somewhat correctly (overpasses, underhangs, and missing building heights cause significant problems.). The ST_PixelsAsCentroids or ST_PixelsAsPoints can be used to get the specific value for a band in the raster, such as the height in a specific 30sq meter area (for the 1 arcsecond resolution of the SRTM data). I could never do such a thing in MySQL, and that makes me sad :( On Wed, Oct 12, 2016 at 9:34 AM, Sergei Golubchik <s...@mariadb.org> wrote: > Hi, Justin! > > On Oct 12, Justin Swanhart wrote: > > > > Regarding SET PERSIST, yes, it has dangers. One of them would be to > > set the buffer pool too large, so I filed a MySQL FR to set the BP to > > the default size if the malloc fails. It can be increased dynamically > > later. But there are many changes that could cause problems. This > > feature has to be managed carefully. Then again, Oracle RDBMS has had > > pfile configuration for well over a decade, and it is functionally > > equivalent to a binary my.cnf in the data dir. > > Right. Personally I fully expect that we will need to suport SET PERSIST > eventually. It's just so convenient. I only said it needs some very > careful thinking - and I was responsible for secur...@mysql.com for ten > years and now for secur...@mariadb.org for six, so I am a bit paranoid > about this :) > > > re: GIS, well, gdal and proj are used by almost every application > > that deals with GIS. What does the extra accuracy get you? Anyway, > > rasters really aren't useful without table functions, as you can't get > > the data from each point without them. > > I don't really know what rasters are. > > And I do not actually *use* GIS, so may be extra accuracy is not useful. > I'd think it might be particularly important for functions like > ST_TOUCHES(). > > I really want MariaDB to have table functions - perhaps we will have > them in 10.3. > > > Some more questions: > > Even though .FRM are optional, that still doesn't necessarily make DDL > > changes atomic, does it? > > If the engine declares FRM optional, then the whole DDL is happening > inside the engine, and it's up to the engine to make it atomic. I > expect that when we'll make FRMs optional for InnoDB, InnoDB DDLs > will be atomic. > > Regards, > Sergei > Chief Architect MariaDB > and secur...@mariadb.org >
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