describe wmf.mediawiki_user_history;
OK
col_name	data_type	comment
wiki_db             	string              	enwiki, dewiki, eswiktionary, etc.
user_id             	bigint              	ID of the user, as in the user table.
user_name           	string              	Historical user name.
user_name_latest    	string              	User name as of today.
user_groups         	array<string>       	Historical user groups.
user_groups_latest  	array<string>       	User groups as of today.
user_blocks         	array<string>       	Historical user blocks.
user_blocks_latest  	array<string>       	User blocks as of today.
user_registration_timestamp	string              	When the user accoung was registered, in YYYYMMDDHHmmss format.
created_by_self     	boolean             	Whether the user created their own account
created_by_system   	boolean             	Whether the user account was created by mediawiki (eg. centralauth)
created_by_peer     	boolean             	Whether the user account was created by another user
anonymous           	boolean             	Whether the user is not registered
is_bot_by_name      	boolean             	Whether the user's name matches patterns we use to identify bots
start_timestamp     	string              	Timestamp from where this state applies (inclusive).
end_timestamp       	string              	Timestamp to where this state applies (exclusive).
caused_by_event_type	string              	Event that caused this state (create, move, delete or restore).
caused_by_user_id   	bigint              	ID from the user that caused this state.
caused_by_block_expiration	string              	Block expiration timestamp, if any.
inferred_from       	string              	If non-NULL, indicates that some of this state's fields have been inferred after an inconsistency in the source data.
snapshot            	string              	Versioning information to keep multiple datasets (YYYY-MM for regular labs imports)
	 	 
# Partition Information	 	 
# col_name            	data_type           	comment             
	 	 
snapshot            	string              	Versioning information to keep multiple datasets (YYYY-MM for regular labs imports)

val df = spark.read.parquet("/wmf/data/wmf/mediawiki/user_history/snapshot=2018-03")
df.printSchema
root
 |-- wiki_db: string (nullable = true)
 |-- user_id: long (nullable = true)
 |-- user_name_historical: string (nullable = true)
 |-- user_name: string (nullable = true)
 |-- user_groups_historical: array (nullable = true)
 |    |-- element: string (containsNull = true)
 |-- user_groups: array (nullable = true)
 |    |-- element: string (containsNull = true)
 |-- user_blocks_historical: array (nullable = true)
 |    |-- element: string (containsNull = true)
 |-- user_blocks: array (nullable = true)
 |    |-- element: string (containsNull = true)
 |-- user_registration_timestamp: string (nullable = true)
 |-- created_by_self: boolean (nullable = true)
 |-- created_by_system: boolean (nullable = true)
 |-- created_by_peer: boolean (nullable = true)
 |-- anonymous: boolean (nullable = true)
 |-- is_bot_by_name: boolean (nullable = true)
 |-- start_timestamp: string (nullable = true)
 |-- end_timestamp: string (nullable = true)
 |-- caused_by_event_type: string (nullable = true)
 |-- caused_by_user_id: long (nullable = true)
 |-- caused_by_block_expiration: string (nullable = true)
 |-- inferred_from: string (nullable = true)