Alfonso Nishikawa created GORA-514:
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Summary: Scan of a single key with a limit clears the persistent
instance when iterating results
Key: GORA-514
URL: https://issues.apache.org/jira/browse/GORA-514
Project: Apache Gora
Issue Type: Bug
Components: gora-accumulo, gora-cassandra, gora-core, gora-hbase,
gora-jcache, gora-mongodb, gora-solr
Affects Versions: 0.7, 0.8
Reporter: Alfonso Nishikawa
Priority: Minor
To put in context, I am just doing a scan where the start key, end key and
limit are configurable:
{code:java}
Query<String,Persistent> dataQuery = dataStore.newQuery() ;
if (startKey != null && !startKey.equals("")) {
dataQuery.setStartKey(startKey);
}
if (endKey != null && !endKey.equals("")) {
dataQuery.setEndKey(endKey);
}
dataQuery.setLimit(limit);
Result<?,Persistent> result = dataQuery.execute();
while (result.next()) {
results.put(result.getKey(), result.get()) ;
}
{code}
When the start key is equal to end key, and the limit is configured to a value
>= (the default value is -1), the second call to result.next() in the while
bucle clears the instance previously returned by result.get().
We could think that this would be an expected behaviour since result.get()
-especifically for HBase- is a reusable instance when performing a Get
operation, but this clashes with the actual expected general behaviour in the
usual Scan operation shown in the former code example.
This is: next() and get() when performing a scan should behave the same no
matter what initial/end keys you configure, and what maximum number of results
you want.
I implemented a test than shows the issue affecting Accumulo, Cassandra, HBase,
JCache, MongoDB and Solr, probably because it is some issue in the core.
To see the error, you can apply the attached patch with the tests example and
execute:
{code:sh}
mvn -Dtest=#testScanSingleResultWithLimit -fn -DfailIfNoTests=false test
{code}
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