What's the best way to support array column types with external tables in hive?

Question

So i have external tables of tab delimited data. A simple table looks like this:

create external table if not exists categories
(id string, tag string, legid string, image string, parent string, created_date string, time_stamp int)
ROW FORMAT DELIMITED FIELDS TERMINATED BY '\t'
LOCATION 's3n://somewhere/';

Now I'm adding another field to the end, it will be a comma separated list of values.

Is there a way to specify this in the same way that I specify a field terminator, or do I have to rely on one of the serdes?

eg:

...list_of_names ARRAY<String>)
ROW FORMAT DELIMITED FIELDS TERMINATED BY '\t' ARRAY ELEMENTS SEPARATED BY ','
...

(I'm assuming I'll need to use a serde for this, but I figured there wasn't any harm in asking)

Answer 1

I don't know how to update an existing table to do that, but for creating a table; what you are looking for can be found, in depth, at https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DDL. A snippet from there

row_format
  : DELIMITED [FIELDS TERMINATED BY char] [COLLECTION ITEMS TERMINATED BY char]
        [MAP KEYS TERMINATED BY char] [LINES TERMINATED BY char]

An example from our table creation is

CREATE TABLE IF NOT EXISTS visits
(
    ... Columns Removed...
)
    PARTITIONED BY (userdate STRING)
    ROW FORMAT DELIMITED
        FIELDS TERMINATED BY '\001'
        COLLECTION ITEMS TERMINATED BY '\002'
        MAP KEYS TERMINATED BY '\003'
    STORED AS TEXTFILE
;

The line from that you'd be looking for is the COLLECTION ITEMS TERMINATED BY char for an array.

hth