org.apache.iotdb.udf.UDTFExample Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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* http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.iotdb.udf;
import org.apache.iotdb.udf.api.UDTF;
import org.apache.iotdb.udf.api.access.Row;
import org.apache.iotdb.udf.api.collector.PointCollector;
import org.apache.iotdb.udf.api.customizer.config.UDTFConfigurations;
import org.apache.iotdb.udf.api.customizer.parameter.UDFParameterValidator;
import org.apache.iotdb.udf.api.customizer.parameter.UDFParameters;
import org.apache.iotdb.udf.api.customizer.strategy.RowByRowAccessStrategy;
import org.apache.iotdb.udf.api.type.Type;
import java.io.IOException;
import java.util.Map;
/** This is an internal example of the UDTF implementation. */
public class UDTFExample implements UDTF {
/**
* CREATE DATABASE root.sg1; CREATE TIMESERIES root.sg1.d1.s1 WITH DATATYPE=INT32, ENCODING=PLAIN;
* CREATE TIMESERIES root.sg1.d1.s2 WITH DATATYPE=INT32, ENCODING=PLAIN; INSERT INTO
* root.sg1.d1(timestamp, s1, s2) VALUES (0, -1, 1); INSERT INTO root.sg1.d1(timestamp, s1, s2)
* VALUES (1, -2, 2); INSERT INTO root.sg1.d1(timestamp, s1, s2) VALUES (2, -3, 3);
*
* CREATE FUNCTION example AS 'org.apache.iotdb.udf.UDTFExample'; SHOW FUNCTIONS; SELECT s1,
* example(s1), s2, example(s2) FROM root.sg1.d1;
*/
@Override
public void validate(UDFParameterValidator validator) throws Exception {
validator
// this udf only accepts 1 time series
.validateInputSeriesNumber(1)
// the data type of the first input time series should be INT32
.validateInputSeriesDataType(0, Type.INT32)
// this udf doesn't accept any extra parameters
// the validation rule is not required because extra parameters will be ignored
.validate(
attributes -> ((Map) attributes).isEmpty(),
"extra udf parameters are not allowed",
validator.getParameters().getAttributes());
}
@Override
public void beforeStart(UDFParameters parameters, UDTFConfigurations configurations) {
configurations.setAccessStrategy(new RowByRowAccessStrategy()).setOutputDataType(Type.INT32);
}
@Override
public void transform(Row row, PointCollector collector) throws IOException {
if (!row.isNull(0)) {
collector.putInt(row.getTime(), -row.getInt(0));
}
}
}