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https://issues.apache.org/jira/browse/CASSANDRA-5867?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13742689#comment-13742689
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Alex Liu commented on CASSANDRA-5867:
-------------------------------------
To store data to CQL3 table, we supports the following prepared statements
{code}
Set
e.g.
UPDATE users SET top_places = ?
UPDATE users SET top_places = [ 'rivendell', 'rohan' ] WHERE user_id =
'frodo';
UPDATE users SET top_places = ? + top_places
UPDATE users SET top_places = [ 'the shire' ] + top_places WHERE user_id =
'frodo';
UPDATE users SET top_places[2] = ?
UPDATE users SET top_places[2] = 'riddermark' WHERE user_id = 'frodo';
DELETE top_places[3] FROM users;
DELETE top_places[3] FROM users WHERE user_id = 'frodo';
UPDATE users SET top_places = top_places - ?;
UPDATE users SET top_places = top_places - ['riddermark'] WHERE user_id =
'frodo';
List statements are similar to Set
Map
UPDATE users SET todo[?] = ?
UPDATE users SET todo['2012-10-2 12:10'] = 'die' WHERE user_id = 'frodo';
UPDATE users SET todo = ?
UPDATE users
SET todo = { '2012-9-24' : 'enter mordor',
'2012-10-2 12:00' : 'throw ring into mount doom' }
WHERE user_id = 'frodo';
{code}
The output schema for collections is as following
{code}
(((name, value), (name, value)), (value ... value), (value...value)
If a value of tuple (value...value) is a tuple of (inner_value ...inner_value)
and the first inner_value is the collection type. it is either "set", "list" or
"map".
e.g. (value ... value) as (value1, value2, ('set', 'riddermark'))
{code}
> The Pig CqlStorage/AbstractCassandraStorage classes don't handle collection
> types
> ---------------------------------------------------------------------------------
>
> Key: CASSANDRA-5867
> URL: https://issues.apache.org/jira/browse/CASSANDRA-5867
> Project: Cassandra
> Issue Type: Bug
> Components: Hadoop
> Reporter: Jeremy Hanna
> Assignee: Alex Liu
> Labels: pig
> Attachments: 5867-1.2-branch.txt, 5867-2-1.2-branch.txt
>
>
> The CqlStorage class gets the Pig data type for values from the
> AbstractCassandraStorage class, in the getPigType method. If it isn't a
> known data type, it makes the value into a ByteArray. Currently there aren't
> any cases there for lists, maps, and sets.
> https://github.com/apache/cassandra/blob/cassandra-1.2.8/src/java/org/apache/cassandra/hadoop/pig/AbstractCassandraStorage.java#L336
> See this describe output from the grunt shell:
> {code}
> grunt> describe listdata ;
> listdata: {id: (name: chararray,value: int),alist: (name: chararray,value:
> bytearray),amap: (name: chararray,value: bytearray),aset: (name:
> chararray,value: bytearray)}
> {code}
> where the cql data structures had this schema:
> {code}
> CREATE TABLE alltypes (
> id int PRIMARY KEY,
> alist list<text>,
> amap map<text, text>,
> aset set<text>
> {code}
> It turns out that if you cast the map in grunt to a pig map, then it sort of
> works, but I don't think we should probably use a pig map. Lists don't
> appear to work at all, as there is no Pig analogue. I *think* you could
> probably just do a UDF to cast these things, but we already have all of the
> type information, so we just need to change them to tuples or bags or
> whatever.
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