public void reduce(
CompositeKeyWritable key, Iterable<KeyValueArrayWritable> values, Context context)
throws IOException, InterruptedException {
/* BERLIN SPARQL BENHCMARK QUERY 8
----------------------------------------
SELECT ?title ?text ?reviewDate ?reviewer ?reviewerName ?rating1 ?rating2 ?rating3 ?rating4
WHERE {
[TP-01] ?review bsbm:reviewFor %ProductXYZ% .
[TP-02] ?review dc:title ?title .
[TP-03] ?review rev:text ?text .
[TP-04] FILTER langMatches( lang(?text), "EN" )
[TP-05] ?review bsbm:reviewDate ?reviewDate .
[TP-06] ?review rev:reviewer ?reviewer .
[TP-07] ?reviewer foaf:name ?reviewerName .
[TP-08] OPTIONAL { ?review bsbm:rating1 ?rating1 . }
[TP-09] OPTIONAL { ?review bsbm:rating2 ?rating2 . }
[TP-10] OPTIONAL { ?review bsbm:rating3 ?rating3 . }
[TP-11] OPTIONAL { ?review bsbm:rating4 ?rating4 . }
}
ORDER BY DESC(?reviewDate)
LIMIT 20
--------------------------------------- */
List<KeyValue> finalKeyValues = new ArrayList<KeyValue>();
// Find the keys for the vendor/publisher
KeyValue kv_reviewer = null;
for (KeyValueArrayWritable array : values) {
for (KeyValue kv : (KeyValue[]) array.toArray()) {
if (Arrays.equals(kv.getValue(), "rev_reviewer".getBytes())) {
kv_reviewer = kv;
finalKeyValues.add(kv);
} else {
finalKeyValues.add(kv);
}
}
}
// TP-07
Result reviewerResult = table.get(new Get(kv_reviewer.getQualifier()));
boolean foundReviewerName = false;
for (KeyValue kv : reviewerResult.list()) {
if (Arrays.equals(kv.getQualifier(), "foaf_name".getBytes())) {
finalKeyValues.add(kv);
foundReviewerName = true;
break;
}
}
if (foundReviewerName == false) {
return;
}
// Format and output the values
StringBuilder builder = new StringBuilder();
builder.append("\n");
for (KeyValue kv : finalKeyValues) {
String[] triple = null;
try {
triple = SharedServices.keyValueToTripleString(kv);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
builder.append(triple[0] + "\t" + triple[1] + "\t" + triple[2] + "\n");
}
context.write(new Text(key.getValue()), new Text(builder.toString()));
}
public void map(ImmutableBytesWritable row, Result value, Context context)
throws InterruptedException, IOException {
/* BERLIN SPARQL BENHCMARK QUERY 8
----------------------------------------
SELECT ?title ?text ?reviewDate ?reviewer ?reviewerName ?rating1 ?rating2 ?rating3 ?rating4
WHERE {
[TriplePattern-01] ?review bsbm:reviewFor %ProductXYZ% .
[TP-02] ?review dc:title ?title .
[TP-03] ?review rev:text ?text .
[TP-04] FILTER langMatches( lang(?text), "EN" )
[TP-05] ?review bsbm:reviewDate ?reviewDate .
[TP-06] ?review rev:reviewer ?reviewer .
[TP-07] ?reviewer foaf:name ?reviewerName .
[TP-08] OPTIONAL { ?review bsbm:rating1 ?rating1 . }
[TP-09] OPTIONAL { ?review bsbm:rating2 ?rating2 . }
[TP-10] OPTIONAL { ?review bsbm:rating3 ?rating3 . }
[TP-11] OPTIONAL { ?review bsbm:rating4 ?rating4 . }
}
ORDER BY DESC(?reviewDate)
LIMIT 20
---------------------------------------*/
String rowKey = new String(value.getRow());
ArrayList<KeyValue> keyValuesToTransmit = new ArrayList<KeyValue>();
List<KeyValue> reviewRow = value.list();
byte[] predicate = value.getValue(SharedServices.CF_AS_BYTES, ProductXYZ.getBytes());
if (!Arrays.equals(predicate, "bsbm-voc_reviewFor".getBytes())) {
return;
}
int requiredColumns = 0;
for (KeyValue kv : reviewRow) {
// TP-01
if (Arrays.equals(kv.getValue(), "bsbm-voc_reviewFor".getBytes())) {
keyValuesToTransmit.add(kv);
requiredColumns++;
}
// TP-02
else if (Arrays.equals(kv.getQualifier(), "dc_title".getBytes())) {
keyValuesToTransmit.add(kv);
requiredColumns++;
}
// TP-03
else if (Arrays.equals(kv.getQualifier(), "rev_text".getBytes())) {
keyValuesToTransmit.add(kv);
requiredColumns++;
}
// TP-04
else if (Arrays.equals(kv.getValue(), "rdfs_lang".getBytes())) {
if (!Arrays.equals(kv.getQualifier(), "@en".getBytes())) {
return;
}
keyValuesToTransmit.add(kv);
requiredColumns++;
}
// TP-05
else if (Arrays.equals(kv.getQualifier(), "bsbm-voc_reviewDate".getBytes())) {
keyValuesToTransmit.add(kv);
requiredColumns++;
}
// TP-06
else if (Arrays.equals(kv.getValue(), "rev_reviewer".getBytes())) {
keyValuesToTransmit.add(kv);
requiredColumns++;
}
// OPTIONAL TP-08, TP-09, TP-10, TP-11
else if (Arrays.equals(kv.getQualifier(), "bsbm-voc_rating1".getBytes())) {
keyValuesToTransmit.add(kv);
} else if (Arrays.equals(kv.getQualifier(), "bsbm-voc_rating2".getBytes())) {
keyValuesToTransmit.add(kv);
} else if (Arrays.equals(kv.getQualifier(), "bsbm-voc_rating3".getBytes())) {
keyValuesToTransmit.add(kv);
} else if (Arrays.equals(kv.getQualifier(), "bsbm-voc_rating4".getBytes())) {
keyValuesToTransmit.add(kv);
}
}
if (requiredColumns < 6) {
return;
}
context.write(
new CompositeKeyWritable(rowKey, 1),
new KeyValueArrayWritable(SharedServices.listToArray(keyValuesToTransmit)));
}
