THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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共进行三种查询:带值过滤的原始数据查询;带值过滤的聚合查询(Count和Max_Value两种),带值过滤的group by查询(Count和Max_Value两种+10-1000不同粒度)
实验结果
如上表所示,可以发现,在进行原始数据查询和聚合查询时,当选择率较低的场景下,查询执行时间有明显的提升,选择率大于50%以后与原有时间持平。
实验代码
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language | java |
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以在集种分布下选择率为0的查询为例:
select s0 from root.sg1.d1 where s0<0
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select s0 from root.sg1.d1 where s0<0
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select max_value(s0) from root.sg1.d1 where s0<0
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select count(s0) from root.sg1.d1 where s0<0 group by ([1, 10000000), 10ms)
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select max_value(s0) from root.sg1.d1 where s0<0 group by ([1, 10000000), 10ms)
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select count(s0) from root.sg1.d1 where s0<0 group by ([1, 10000000), 100ms)
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select max_value(s0) from root.sg1.d1 where s0<0 group by ([1, 10000000), 100ms)
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select count(s0) from root.sg1.d1 where s0<0 group by ([1, 10000000), 1000ms)
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select max_value(s0) from root.sg1.d1 where s0<0 group by ([1, 10000000), 1000ms)
实验结果
如上表所示,可以发现,在进行原始数据查询和聚合查询时,当选择率较低的场景下,查询执行时间有明显的提升,选择率大于50%以及groupby查询的场景下与原有时间持平。
实验代码
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import org.apache.iotdb.jdbc.IoTDBSQLException; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; public class JDBCQuery {", "select max_value(s0) from root.sg1.d1 where s0<=1000000 group by ([1, 10000000), 1000ms)", "select max_value(s0) from root.sg1.d1 where s0<=1000000&s1=1 group by ([1, 10000000), 1000ms)", "select max_value(s0) from root.sg1.d1 where s0<=10000000 group by ([1, 10000000), 1000ms)", "select max_value(s1) from root.sg1.d1 where s1=1 group by ([1, 10000000), 1000ms)", "select max_value(s0) from root.sg1.d1 where s0<=50000000 group by ([1, 10000000), 1000ms)", "select max_value(s1) from root.sg1.d1 where s1<=5 group by ([1, 10000000), 1000ms)", "select max_value(s0) from root.sg1.d1 where s0>0 group by ([1, 10000000), 1000ms)" }; public static void main(String[] args) throws ClassNotFoundException, SQLException { Class.forName("org.apache.iotdb.jdbc.IoTDBDriver"); try (Connection connection = DriverManager.getConnection("jdbc:iotdb://127.0.0.1:6667/", "root", "root"); Statement statement = connection.createStatement()) { //String setsql JDBC= fetchSize "select s0 statement.setFetchSize(10000); String sql = sqls[0]from root.sg1.d1 where s0<0"; System.out.println(sql); long startTime=System.currentTimeMillis(); ResultSet resultSet = statement.executeQuery(sql); outputResult(resultSet); long endTime=System.currentTimeMillis(); System.out.println("time: "+(endTime-startTime)+"ms"); } catch (IoTDBSQLException e) { System.out.println(e.getMessage()); } } private static void outputResult(ResultSet resultSet) throws SQLException { if (resultSet != null) { System.out.println("--------------------------"); System.out.println(); while (resultSet.next()) { } } System.out.println("--------------------------\n"); } } |
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