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 <serg@mariadb.org> wrote:

Hi, Justin!

On Oct 12, Justin Swanhart wrote:

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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 security@mysql.com for ten years and now for security@mariadb.org for six, so I am a bit paranoid about this :)

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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.

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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 security@mariadb.org