CODEWITHSUNDEEP
javacassandrapelops
arsenal
arsenal

Reputation: 24154

Get specified columns data from Cassandra database not all the columns data

I am working with Cassandra database. I have created one column family which has 10 columns in that.

Now I am interested in retrieving only the columns that I required. I don't need to retrieve all the columns value from the Cassandra database.

Suppose if I have below columns in my column family users.

colA
colB
colC
colD

And I need to get only colA and colB data from Cassandra database. Then what I am supposed to do? I don't want to get all the columns data from Cassandra and then loop around to get the required columns.

Something like-

SELECT colA, colB from table1;

I am working with Pelops client.

Below is my code.

public void readTest() {
        // read back the data we just wrote
        Selector selector = Pelops.createSelector(poolName);
        List<Column> columns = selector.getColumnsFromRow(colFamilyName, rowKey, false, ConsistencyLevel.ONE);

        System.out.println("Name: " + Selector.getColumnStringValue(columns, "name"));
        System.out.println("Age: " + Selector.getColumnValue(columns, "age").toInt());

    }

Upvotes: 1

Views: 274

Answers (1)

Zanson
Zanson

Reputation: 4031

You need to use a getColumnsFromRow call which takes a "SlicePredicate" to specify the column names. Such as:

getColumnsFromRow(String columnFamily, Bytes rowKey, SlicePredicate colPredicate, ConsistencyLevel cLevel)

Upvotes: 2

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