我试图把方解石和Kafka结合起来,我引用了csvstreamable。
每个consumerrecord都使用fowlloing代码转换为对象[]:
static class ArrayRowConverter extends RowConverter<Object[]> {
private List<Schema.Field> fields;
public ArrayRowConverter(List<Schema.Field> fields) {
this.fields = fields;
}
@Override
Object[] convertRow(ConsumerRecord<String, GenericRecord> consumerRecord) {
Object[] objects = new Object[fields.size()+1];
int i = 0 ;
objects[i++] = consumerRecord.timestamp();
for(Schema.Field field : this.fields) {
Object obj = consumerRecord.value().get(field.name());
if( obj instanceof Utf8 ){
objects[i ++] = obj.toString();
}else {
objects[i ++] = obj;
}
}
return objects;
}
}
枚举器的实现如下,一个线程不断地轮询来自kafka的记录并将它们放入队列,getrecord()方法从该队列轮询:
public E current() {
return current;
}
public boolean moveNext() {
for(;;) {
if(cancelFlag.get()) {
return false;
}
ConsumerRecord<String, GenericRecord> record = getRecord();
if(record == null) {
try {
Thread.sleep(200L);
} catch (InterruptedException e) {
e.printStackTrace();
}
continue;
}
current = rowConvert.convertRow(record);
return true;
}
}
我测试过了 SELECT STREAM * FROM Kafka.clicks
,工作正常。rowtime是显式添加的第一列,其值是kafka的记录时间戳。
但当我试着
SELECT STREAM FLOOR(rowtime TO HOUR)
AS rowtime,ip,COUNT(*) AS c FROM KAFKA.clicks GROUP BY FLOOR(rowtime TO HOUR), ip
它引发了异常
java.sql.SQLException: Error while executing SQL "SELECT STREAM FLOOR(rowtime TO HOUR) AS rowtime,ip,COUNT(*) AS c FROM KAFKA.clicks GROUP BY FLOOR(rowtime TO HOUR), ip": From line 1, column 85 to line 1, column 119: Streaming aggregation requires at least one monotonic expression in GROUP BY clause
at org.apache.calcite.avatica.Helper.createException(Helper.java:56)
at org.apache.calcite.avatica.Helper.createException(Helper.java:41)
1条答案
按热度按时间ryhaxcpt1#
您需要声明“rowtime”列是单调的。在
MockCatalogReader
,注意“orders”和“shippings”流中“rowtime”是如何声明为单调的。这就是为什么有些查询SqlValidatorTest.testStreamGroupBy()
是有效的,其他的不是。验证器依赖的关键方法是SqlValidatorTable.getMonotonicity(String columnName)
.