在pig0.11.0之后，引入了datetime基本变量类型进行处理。就我而言，我必须按日期和时间订货。我用这种方式

data = LOAD 'database_name.table_name' USING org.apache.hcatalog.pig.HCatLoader() AS (id:chararray,name:chararray,birth_date_time:chararray);

selected_data = FOREACH data GENERATE id, name,ToDate(birth_date_time,'yyyy-MM-dd HH:mm:ss') AS birth_date_time;

ordered_data = ORDER selected_data BY birth_date_time DESC;

DUMP ordered_data;

但我不工作。抛出此错误
org.apache.pig.impl.logicalayer.frontendexception:错误1066:无法打开别名cba的迭代器。后端错误：无法从备份的错误中重新创建异常：attemptid:attempt_1452577118821_0005_m_000000_3 info:error：org.joda.time.datetime.compareto（lorg/joda/time/readableinstant；）我在org.apache.pig.pigserver.openiterator（pigserver。java:872)位于org.apache.pig.tools.grunt.gruntparser.processdump（gruntparser。java:774)在org.apache.pig.tools.pigscript.parser.pigscriptparser.parse（pigscriptparser。java:372)在org.apache.pig.tools.grunt.gruntparser.parsestoponerror（gruntparser。java:198)在org.apache.pig.tools.grunt.gruntparser.parsestoponerror（gruntparser。java:173)在org.apache.pig.tools.grunt.grunt.exec（grunt。java:84)在org.apache.pig.main.run（main。java:607)在org.apache.pig.main.main（main。java:156)位于sun.reflect.nativemethodaccessorimpl.invoke0（本机方法）sun.reflect.nativemethodaccessorimpl.invoke（nativemethodaccessorimpl。java:57)在sun.reflect.delegatingmethodaccessorimpl.invoke（delegatingmethodaccessorimpl。java:43)在java.lang.reflect.method.invoke（方法。java:606)在org.apache.hadoop.util.runjar.main（runjar。java:212)原因：org.apache.pig.backend.executionengine.execute:错误2997:无法从备份的错误中重新创建异常：attemptid:attempt_1452577118821_0005_m_000000_3 info:error：org.joda.time.datetime.compareto（lorg/joda/time/readableinstant；）我在org.apache.pig.backend.hadoop.executionengine.mapreducelayer.launcher.geterrormessages（launcher。java:217)在org.apache.pig.backend.hadoop.executionengine.mapreducelayer.launcher.getstats（launcher。java:151)位于org.apache.pig.backend.hadoop.executionengine.mapreducelayer.mapreducelauncher.launchpig（mapreducelauncher）。java:429)在org.apache.pig.pigserver.launchplan（pigserver。java:1324)在org.apache.pig.pigserver.executecompiledlogicalplan（pigserver。java:1309)在org.apache.pig.pigserver.storeex（pigserver。java:980)在org.apache.pig.pigserver.store（pigserver。java:944)在org.apache.pig.pigserver.openiterator（pigserver。java:857) ... 12个以上
我们如何按日期和时间字段订购？