要将Apache Arrow适配器与Apache Calcite集成,您需要遵循以下步骤:
首先,确保您已经安装了Apache Arrow和Apache Calcite的依赖项。
创建一个新的Java项目,并将以下依赖项添加到您的项目的pom.xml文件中:
org.apache.arrow
arrow-vector
${arrow.version}
org.apache.arrow
arrow-memory
${arrow.version}
org.apache.arrow
arrow-flight
${arrow.version}
org.apache.calcite
calcite-core
${calcite.version}
org.apache.calcite
calcite-avatica
${calcite.version}
请确保将${arrow.version}
和${calcite.version}
替换为您所使用的Apache Arrow和Apache Calcite版本。
import org.apache.arrow.memory.RootAllocator;
import org.apache.arrow.vector.VarCharVector;
import org.apache.calcite.DataContext;
import org.apache.calcite.adapter.java.AbstractQueryableTable;
import org.apache.calcite.linq4j.AbstractEnumerable;
import org.apache.calcite.linq4j.EnumerableDefaults;
import org.apache.calcite.linq4j.QueryProvider;
import org.apache.calcite.linq4j.Queryable;
import org.apache.calcite.linq4j.tree.Expression;
import org.apache.calcite.linq4j.tree.Expressions;
import org.apache.calcite.rel.type.RelDataType;
import org.apache.calcite.rel.type.RelDataTypeFactory;
import org.apache.calcite.rel.type.RelProtoDataType;
import org.apache.calcite.schema.SchemaPlus;
import org.apache.calcite.schema.impl.AbstractSchema;
import org.apache.calcite.schema.impl.TableMacroImpl;
import org.apache.calcite.schema.impl.ViewTableMacroImpl;
import org.apache.calcite.schema.impl.ViewTableImpl;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
public class ArrowAdapterIntegrationExample {
public static void main(String[] args) {
// Create a new schema
SchemaPlus schema = Frameworks.createRootSchema(true);
// Register the Arrow adapter with Calcite
schema.add("arrow", new ArrowSchema());
// Create a new Calcite connection
Properties info = new Properties();
info.setProperty("model", ArrowAdapterIntegrationExample.class.getResource("/model.json").getPath());
Connection connection = DriverManager.getConnection("jdbc:calcite:", info);
// Use the Calcite connection to execute a query
Statement statement = connection.createStatement();
ResultSet resultSet = statement.executeQuery("SELECT * FROM arrow.test");
// Process the query result
while (resultSet.next()) {
System.out.println(resultSet.getString(1));
}
// Close the resources
resultSet.close();
statement.close();
connection.close();
}
public static class ArrowSchema extends AbstractSchema {
@Override
protected Map getTableMap() {
Map tableMap = new HashMap<>();
// Create a new Arrow table
Table table = new AbstractQueryableTable(ArrowAdapterIntegrationExample.ArrowTable.class) {
@Override
public RelDataType getRowType(RelDataTypeFactory typeFactory) {
List types = Arrays.asList(
typeFactory.createJavaType(String.class)
);
List fieldNames = Collections.singletonList("name");
return typeFactory.createStructType(types, fieldNames);
}
@Override
public Queryable asQueryable(QueryProvider queryProvider, SchemaPlus schema, String tableName) {
return new AbstractEnumerable() {
@Override
public Enumerator enumerator() {
return (Enumerator) new ArrowEnumerator();
}
};
}
};
tableMap.put("test", table);
return tableMap;
}
}
public static class ArrowTable {
public String name;
}
public static class ArrowEnumerator implements Enumerator