CREATE EXTERNAL TABLE grid_10 (id bigint, json STRING)
ROW FORMAT DELIMITED FIELDS TERMINATED BY 't'
LINES TERMINATED BY 'n'
STORED AS TEXTFILE
LOCATION 's3://some-url/data/grids/geojson';

create table grid_cnt as
SELECT grid_10.id, count(grid_10.id) as ptcnt FROM grid_10 JOIN tweets     WHERE ST_Contains(ST_GeomFromGeoJSON(grid_10.json),ST_Point(tweets.longitude,   tweets.latitude))=true GROUP BY grid_10.id;