/**
* Get a Schema with fields represented with native Hive types
*/
public static Schema getSchema(BaseSemanticAnalyzer sem, HiveConf conf) {
Schema schema = null;
// If we have a plan, prefer its logical result schema if it's
// available; otherwise, try digging out a fetch task; failing that,
// give up.
if (sem == null) {
// can't get any info without a plan
} else if (sem.getResultSchema() != null) {
List<FieldSchema> lst = sem.getResultSchema();
schema = new Schema(lst, null);
} else if (sem.getFetchTask() != null) {
FetchTask ft = sem.getFetchTask();
TableDesc td = ft.getTblDesc();
// partitioned tables don't have tableDesc set on the FetchTask. Instead
// they have a list of PartitionDesc objects, each with a table desc.
// Let's
// try to fetch the desc for the first partition and use it's
// deserializer.
if (td == null && ft.getWork() != null && ft.getWork().getPartDesc() != null) {
if (ft.getWork().getPartDesc().size() > 0) {
td = ft.getWork().getPartDesc().get(0).getTableDesc();
}
}
if (td == null) {
LOG.info("No returning schema.");
} else {
String tableName = "result";
List<FieldSchema> lst = null;
try {
lst = MetaStoreUtils.getFieldsFromDeserializer(tableName, td.getDeserializer());
} catch (Exception e) {
LOG.warn("Error getting schema: "
+ org.apache.hadoop.util.StringUtils.stringifyException(e));
}
if (lst != null) {
schema = new Schema(lst, null);
}
}
}
if (schema == null) {
schema = new Schema();
}
LOG.info("Returning Hive schema: " + schema);
return schema;
}