/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.tajo.engine.function.builtin;
import org.apache.tajo.catalog.CatalogUtil;
import org.apache.tajo.catalog.Column;
import org.apache.tajo.common.TajoDataTypes.DataType;
import org.apache.tajo.common.TajoDataTypes.Type;
import org.apache.tajo.datum.Datum;
import org.apache.tajo.datum.DatumFactory;
import org.apache.tajo.datum.Float4Datum;
import org.apache.tajo.engine.function.AggFunction;
import org.apache.tajo.engine.function.FunctionContext;
import org.apache.tajo.engine.function.annotation.Description;
import org.apache.tajo.engine.function.annotation.ParamTypes;
import org.apache.tajo.storage.Tuple;
@Description(
functionName = "min",
description = "the minimum value of expr",
example = "> SELECT min(expr);",
returnType = Type.FLOAT4,
paramTypes = {@ParamTypes(paramTypes = {Type.FLOAT4})}
)
public class MinFloat extends AggFunction<Float4Datum> {
public MinFloat() {
super(new Column[] {
new Column("expr", Type.FLOAT4)
});
}
@Override
public FunctionContext newContext() {
return new MinContext();
}
@Override
public void eval(FunctionContext ctx, Tuple params) {
MinContext minCtx = (MinContext) ctx;
minCtx.min = Math.min(minCtx.min, params.get(0).asFloat4());
}
@Override
public Datum getPartialResult(FunctionContext ctx) {
return DatumFactory.createFloat4(((MinContext) ctx).min);
}
@Override
public DataType getPartialResultType() {
return CatalogUtil.newSimpleDataType(Type.FLOAT4);
}
@Override
public Float4Datum terminate(FunctionContext ctx) {
return DatumFactory.createFloat4(((MinContext) ctx).min);
}
private class MinContext implements FunctionContext {
float min = Float.MAX_VALUE;
}
}