MAPKEYS
Returns the virtual columns (and values) present in any VMap data. This transform function requires an over(PARTITION BEST)
clause.
Syntax
mapkeys(VMap_data)
Arguments
VMap_data |
Any VMap data. The VMap can exist as:
|
Examples
Determine Number of Virtual Columns in Map Data
This example shows how to create a query, using an over(PARTITION BEST)
clause with a flex table, darkdata
to find the number of virtual column in the map data. The table is populated with JSON tweet data.
=> SELECTcount(keys) FROM (SELECT mapkeys(darkdata.__raw__) over(PARTITION BEST) from darkdata) as a;
count ------- 550 (1 row)
Query Ordered List of All Virtual Columns in the Map
This example shows a snippet of the return data when you query an ordered list of all virtual columns in the map data:
=> SELECT * FROM (SELECT mapkeys(darkdata.__raw__) over(PARTITION BEST) from darkdata) as a;
keys ------------------------------------- contributors coordinates created_ at delete.status.id delete.status.id_str delete.status.user_id delete.status.user_id_str entities.hashtags entities.media entities.urls entities.user_mentions favorited geo id . . . user.statuses_count user.time_zone user.url user.utc_offset user.verified (125 rows)