Access cassandra map element

Question

From the documentation, it seems like we should be able to query individual map elements:

http://www.datastax.com/documentation/cql/3.1/cql/cql_using/use_map_t.html

Each element of the map is internally stored as one Cassandra column that you can modify, replace, delete, and query.

The examples show updating individual elements, but similar syntax doesn't seem to work for select statements. Is there a way to select only one key-value for a map column?

score 4 · Accepted Answer · answered Nov 26 '14 at 16:17

4

You can not retrieve part of a collection: even if internally each entry of a map is stored as a column you can only retrieve the whole collection

answered Nov 26 '14 at 16:17

Carlo Bertuccini

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That's what I thought. Unfortunate. You can update parts, but only querying parts is still a no. – ashic Nov 26 '14 at 16:41
You can query a collection to know if it contains something but you can not retrieve only a portion of the collection – Carlo Bertuccini Nov 26 '14 at 16:46
Could you give an example of the former? – ashic Nov 26 '14 at 17:14
Take a look here: http://stackoverflow.com/questions/25098451/cql3-each-row-to-have-its-own-schema – Carlo Bertuccini Nov 26 '14 at 17:41
So said. I do some research, only find a way to do this is to use the UDF. [Accessing Cassandra Map values](https://davefelcey.wordpress.com/2016/09/19/accessing-cassandra-map-values/) – arganzheng Jun 16 '19 at 11:49

Access cassandra map element

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