Hi, In Impala, is it possible to project map keys from a MAP<string, string> as actual columns in the result set?  I'm ingesting a dataset where we can't know all the possible attributes ahead of time and so we're using a map<string, string> column for maximum flexibility.  However, at query time we still want to pull those attributes out as their own column.   Simplified example below with a few unique keys (in reality there are hundreds of keys in our dataset)   Schema: Column Type name STRING props MAP<string, string>       Raw Table: Name Props Bob {"age": "39", "fav_color": "green"} Alice {"fav_animal": "dog", "fav_color": "blue"}     Desired result: name age fav_color fav_animal Bob 39 green NULL Alice NULL blue dog     I can get all the results in a row-oriented manner by select name, props.key, props.value from table, table.props props;   But, I've not been able to figure out how to make those keys from the MAP type column into their own columns.  Is there a efficient way to do this in Impala?   ... View more

Hopefully easy question, but this works:   select * from mytable;      And this doesn't work: select struct_col.field from mytable; Error message:   java.lang.ClassNotFoundException: Class org.apache.hive.hcatalog.data.JsonSerDe not found     This error doesn't make any sense to me because wouldn't the JsonSerDe have to be available to do the first select * statement?  Any tips on how to resolve this? Many thanks.   Using CDH 5.15.     The `show create table mytable` looks like   CREATE EXTERNAL TABLE `mytable`( | | `name` string COMMENT 'from deserializer', | | `struct_col` struct<field:boolean,other:boolean,thing:boolean> COMMENT 'from deserializer') | | ROW FORMAT SERDE | | 'org.apache.hive.hcatalog.data.JsonSerDe' | | STORED AS INPUTFORMAT | | 'org.apache.hadoop.mapred.TextInputFormat' | | OUTPUTFORMAT | | 'org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat' | | LOCATION | | 'hdfs://host:8020/user/bob/mytable' | | TBLPROPERTIES ( | | 'COLUMN_STATS_ACCURATE'='false', | | 'numFiles'='1', | | 'numRows'='-1', | | 'rawDataSize'='-1', | | 'totalSize'='581', | | 'transient_lastDdlTime'='1544062948') |       ... View more