org.apache.hadoop.hive.ql.udf.generic.UDFCurrentDB Maven / Gradle / Ivy
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package org.apache.hadoop.hive.ql.udf.generic;
import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.MapredContext;
import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.session.SessionState;
import org.apache.hadoop.hive.ql.udf.UDFType;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.typeinfo.TypeInfoFactory;
import org.apache.hadoop.io.Text;
// This function is not a deterministic function, but a runtime constant.
// The return value is constant within a query but can be different between queries.
@UDFType(deterministic = false, runtimeConstant = true)
@Description(name = "current_database",
value = "_FUNC_() - returns currently using database name")
@NDV(maxNdv = 1)
public class UDFCurrentDB extends GenericUDF {
private MapredContext context;
@Override
public void configure(MapredContext context) {
this.context = context;
}
@Override
public ObjectInspector initialize(ObjectInspector[] arguments) throws UDFArgumentException {
String database;
if (context != null) {
database = context.getJobConf().get("hive.current.database");
} else {
database = SessionState.get().getCurrentDatabase();
}
return PrimitiveObjectInspectorFactory.getPrimitiveWritableConstantObjectInspector(
TypeInfoFactory.stringTypeInfo, new Text(database));
}
@Override
public Object evaluate(DeferredObject[] arguments) throws HiveException {
return SessionState.get().getCurrentDatabase();
}
@Override
public String getDisplayString(String[] children) {
return "current_database()";
}
}