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https://issues.apache.org/jira/browse/CARBONDATA-3548?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17011544#comment-17011544 ]
Venugopal Reddy K edited comment on CARBONDATA-3548 at 1/10/20 4:51 AM:
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Updated for
# algorithm description.
# Modified polygon UDF syntax as -
IN_POLYGON('116.321011 40.123503, 116.137676 39.947911, 116.560993 39.935276, 116.321011 40.123503')
# Used IN filter expression with a LIST expression containing all the geohashIds to be filtered instead of RANGE filter expression as this improves the query performance significantly.
was (Author: venureddy):
Updated for
# algorithm description.
# Used IN filter expression with a LIST expression containing all the geohashIds to be filtered instead of RANGE filter expression as this improves the query performance significantly.
> Support for Geospatial indexing
> -------------------------------
>
> Key: CARBONDATA-3548
> URL:
https://issues.apache.org/jira/browse/CARBONDATA-3548> Project: CarbonData
> Issue Type: New Feature
> Reporter: Venugopal Reddy K
> Priority: Major
> Attachments: Geospatial Index Design Doc-OpenSource-Version 2.0.pdf, Geospatial Index Design Doc-OpenSource.pdf
>
> Time Spent: 63h
> Remaining Estimate: 0h
>
> In general, database may contain geographical location data. For instance, Telecom operators require to perform analytics based on a particular region, cell tower IDs(within a region) and/or may include geographical locations for a particular period of time. At present, Carbon do not have native support to store geographical locations/coordinates and to do filter queries based on them. Yet, longitude and latitude of coordinates can be treated as independent columns, sort hierarchically and store them.
> But, when longitude and latitude are treated independently, 2D space is linearized i.e., points in the two dimensional domain are ordered by sorting first on longitide and then on latitude. Thus, data is not ordered by geospatial proximity. Hence range queries require lot of IO operations and query performance is degraded.
> To alleviate it, we can use z-order curve to store geospatial data points. This ensures that geographically nearer points are present at same block/blocklet. This reduces the IO operations for range queries and improves query performance. Also can support polygon queries of geodata. Attached design document describes in detailed.
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