Thank you for replying,
In fact, i'm trying to run this script:
grunt> rows = LOAD 'cassandra://Keyspace1/Users' USING CassandraStorage()
AS (key, columns: bag {T: tuple(name, value)});
grunt> cols = FOREACH rows GENERATE flatten(columns);
grunt> colnames = FOREACH cols GENERATE $0;
grunt> namegroups = GROUP colnames BY (chararray) $0;
grunt> namecounts = FOREACH namegroups GENERATE COUNT($1), group;
grunt> orderednames = ORDER namecounts BY $0;
grunt> topnames = LIMIT orderednames 50;
grunt> dump topnames;but i'm having this error: ERROR org.apache.pig.tools.grunt.Grunt - ERROR 1070: Could not resolve CassandraStorage using imports: [, org.apache.pig.builtin., org.apache.pig.impl.builtin.] 2013/3/18 Dan DeCapria, CivicScience <[email protected]> > Storing to Cassandra requires a key->column->value data structure from pig. > Here is one possible approach, requiring a udf to handle the pig > formatting interchange to cassandra: > > -- sample pig script > A = LOAD 'foo' USING PigStorage() AS (key:chararray, name:chararray, > value:chararray); > B = FOREACH A GENERATE > > FLATTEN(com.to.udf.ToCassandraUDF(TOTUPLE('PotentialKeyManipulation/',$0,'/toSomethingElse'), > TOTUPLE($1), $2)); > STORE B INTO 'cassandra://cassandraNamespace/myColumnFamilyName' USING > org.apache.cassandra.hadoop.pig.CassandraStorage(); > > -- sample toCassandraUDF > package com.to.udf.ToCassandraUDF; > > public class ToCassandraUDF extends EvalFunc<Tuple> { > > public Tuple exec(Tuple input) throws IOException { > Tuple row = TupleFactory.getInstance().newTuple(2); > StringBuffer buf = null; > Tuple keyParts = (Tuple) input.get(0); > buf = new StringBuffer(); > for (Object o : keyParts.getAll()) { > if (o != null) { > buf.append(o.toString()); > } else { > buf.append("null"); > } > } > String key = buf.toString(); > Tuple columnParts = (Tuple) input.get(1); > buf = new StringBuffer(); > for (Object o : columnParts.getAll()) { > if (o != null) { > buf.append(o.toString()); > } else { > buf.append("null"); > } > } > String columnName = buf.toString(); > > byte[] columnValueBytes = null; > if (input.size() > 2) { > Object value = input.get(2); > columnValueBytes = value.toString().getBytes(); > } else { > columnValueBytes = new byte[0]; > } > > Tuple column = TupleFactory.getInstance().newTuple(2); > column.set(0, new DataByteArray(columnName.getBytes())); > column.set(1, new DataByteArray(columnValueBytes)); > > DataBag bagOfColumns = BagFactory.getInstance().newDefaultBag(); > bagOfColumns.add(column); > > row.set(0, key); > row.set(1, bagOfColumns); > > return row; > } > > public Schema outputSchema(Schema input) { > try { > Schema.FieldSchema keyField = new Schema.FieldSchema("key", > DataType.CHARARRAY); > Schema.FieldSchema nameField = new Schema.FieldSchema("name", > DataType.CHARARRAY); > Schema.FieldSchema valueField = new Schema.FieldSchema("value", > DataType.BYTEARRAY); > > Schema bagSchema = new Schema(); > bagSchema.add(nameField); > bagSchema.add(valueField); > > Schema.FieldSchema columnsField = new Schema.FieldSchema("columns", > bagSchema, DataType.BAG); > > Schema innerSchema = new Schema(); > innerSchema.add(keyField); > innerSchema.add(columnsField); > > Schema.FieldSchema cassandraTuple = new Schema.FieldSchema( > "cassandra_tuple", innerSchema, DataType.TUPLE); > > Schema schema = new Schema(cassandraTuple); > schema.setTwoLevelAccessRequired(true); > return schema; > } catch (Exception e) { > return null; > } > } > } > > Hope this helps. > > -Dan > > On Mon, Mar 18, 2013 at 11:15 AM, Mohammed Abdelkhalek < > [email protected]> wrote: > > > Hi, > > i'm using hadoop 1.0.4, cassandra 1.2.2 and pig 0.11.0. > > Can any one help me with an example on how to use pig either for Storing > to > > cassandra from *pig* using Cassandrastorage, or Loading rows from > cassandra > > in order to use them with pig. > > Thanks. > > > > -- > > Mohammed ABDELKHALEK > > Ingénieur d'état de l’École Mohammadia d'Ingénieurs > > Technologies et services de l'information > > Téléphone: +212 6 45 64 65 68 > > > > Préservons l'environnement. N'imprimez ce courriel que si nécessaire. > > Please consider the environment before printing this e-mail. > > > -- Mohammed ABDELKHALEK Ingénieur d'état de l’École Mohammadia d'Ingénieurs Technologies et services de l'information Téléphone: +212 6 45 64 65 68 Préservons l'environnement. N'imprimez ce courriel que si nécessaire. Please consider the environment before printing this e-mail.
