VenuReddy2103 commented on a change in pull request #3520: [WIP]add spatial-index user guid to doc URL: https://github.com/apache/carbondata/pull/3520#discussion_r364701741
########## File path: docs/spatial-index-guide.md ########## @@ -0,0 +1,94 @@ +<!-- + Licensed to the Apache Software Foundation (ASF) under one or more + contributor license agreements. See the NOTICE file distributed with + this work for additional information regarding copyright ownership. + The ASF licenses this file to you under the Apache License, Version 2.0 + (the "License"); you may not use this file except in compliance with + the License. You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. +--> + +## What is spatial index + +A spatial index is a data structure that allows for accessing a spatial object efficiently. It is a common technique used by spatial databases. Without indexing, any search for a feature would require a "sequential scan" of every record in the database, resulting in much longer processing time. In a spatial index construction process, the minimum bounding rectangle serves as an object approximation. Various types of spatial indices across commercial and open-source databases yield measurable performance differences. Spatial indexing techniques are playing a central role in time-critical applications and the manipulation of spatial big data. + + + +## What does carbondata implement spatial index + +There are many components that implement spatial indexing, like GeoSpark that use GeoMesa format for spatial query. now carbondata implements a different way of spatial index, more like an UDF. Its core is to use grid coordinates to generate coordinate based hash ID, like Z order, it's also regionally continuous. Review comment: Have read the text and have few suggestions on repharsing certain parts of it, To be clear, have attached the modified text below. Can we rephrase like this --> `There are many opensource implementations for spatial indexing and to process spatial queries. CarbonData implements a different way of spatial index. Its core idea is to use the raster data. Raster is made up of matrix of cells organized into rows and columns(called a grid). Each cell represents a coordinate. And the index for that coodrinate is generated using longitude and latitude, like the Z order curve.` `CarbonData requires rasterization of data before loading into segments. A set of latitude and longitude represents a grid range. The size of the grid can be configured. Hence, the coordinates loaded are often discrete and not continuous.` ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
