|[geowave-dev] Accumulo Key Structure - Storing Point Data|
Hello,IÂ´ve got a couple of questions when storing point data. In the attachment you can find a drawing with my current understanding how this key structure might work.
I read your presentation at the accumulo summit, but itÂ´s not quite clear how to determine some values.
http://accumulosummit.com/program/talks/geowave-geospatial-and-geotemporal-data-storage-and-retrieval-in-accumulo/IÂ´ve chosen a very simple case with 8 cubes. The whole cube represents the world from 2000-2015 (16 years). If I want to store my Point P(30, -180, 2010-01-01) it is said that we first have to determine the "tier". Because itÂ´s a point it will be stored in the highest tier number. In my case there are only tier 0 and tier 1. Now itÂ´s up to the bin. This is where my presumptions starts: We need a binID...In my drawing this is done by using a Hilbert-curve. Is this correct? Because my point P is the last of the 8 sub-cubes, binID would set to 8. Because the date range is known this could be done without any problems. But when I want to add my point P to Accumulo without having any additional information this would causes some problems. Is there are default date range which is used? Or will the binID added later on, when all data is in Accumulo (now we know the daterange)? Each bin has its own hilbert space. But which resolution do you use? (in my drawing its also first order hilbert curve). Where do you store the boundaries for each bin (or are they calculated on the fly)? The resulting entries in Accumulo for my example is at the bottom of my sheet of paper. Within the accumulo structure I canÂ´t see a parameter which partitions the data evenly across my nodes. Do you avoid hotspots with a random prefix?
I hope my sketch helps a little bit that you can understand what my problems are with the Accumulo key structure. Please correct me if my drawing is wrong. But itÂ´s hard to get an understanding of this complex structure.
Is there a method which returns an entry in the accumulo data format? I wrote a Scanner, but part of the results of the rowId were not readable: "2003>)æ bï¿¿geowave-gdelt260176188"
Thanks in advance, Marcel Jacob.
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