Re: [geomesa-users] Accumulo Key Structure

[Chris Eichelberger <cne1x@xxxxxxxx>]

Marcel,

Yes, we have changed the Spatio-Temporal index structure some since the
initial publication of GeoMesa.

Yes, the ColQ now consists solely of the feature ID by default.

Yes, we have changed the allocation of Geohash strings from the initial
paper.

Yes, we have introduced the "0" "1" -- that you labeled "???" after the
sharding key -- do ensure that index entries and data entries for a
given entry are contained in predictable blocks in predictable order.

It's fun saying, "yes."

Thanks!

Sincerely,
  -- Chris


On Mon, 2015-10-12 at 17:30 +0200, Marcel wrote:
> Hello,
> I scanned some rows of the deprecated _st_idx table to comprehend the 
> index key structure described in the paper.
> This results in the following:
> 
> structure in paper:
> RowID Column Family Column Qualifier
> ##~geohashPart1(char 1)~datePart1 geohashPart2(char 2-4) 
> ident.~geohashPart3(char 5-7)~datePart2
> 
> vs.
> observed structure:
> 
> shardingKey?~???~featureName~geohashPart1(char 1-3)~fullDate 
> geohashPart2 (char 4-5) hex-values?
> example:
> 0~0~event~rhe~2014113023 4r 909271fc-44fa-495b-b876-5843df987fef
> 
> So obviously the structure has changed. It seems that the date is fully 
> encoded in the rowId. Also the number of geohash characters changed. But 
> I can´t understand what is stored within the qualifier? Is it only the 
> identifier?
> 
> Best regards,
> Marcel Jacob.
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