如何让cassandra正确过滤？

Question

我是cassandra的新手，目前正在尝试datastax的温度范例。 在这个例子中，我创建具有以下DDL的表：包含以下数据

CREATE TABLE mykeyspace.temperature (
    weatherstation_id text, 
    event_time timestamp, 
    temperature text, 
    PRIMARY KEY (weatherstation_id, event_time) 
) WITH read_repair_chance = 0.0 
    AND dclocal_read_repair_chance = 0.1 
    AND gc_grace_seconds = 864000 
    AND bloom_filter_fp_chance = 0.01 
    AND caching = { 'keys' : 'ALL', 'rows_per_partition' : 'NONE' } 
    AND comment = '' 
    AND compaction = { 'class' : 'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy', 'max_threshold' : 32, 'min_threshold' : 4 } 
    AND compression = { 'chunk_length_in_kb' : 64, 'class' : 'org.apache.cassandra.io.compress.LZ4Compressor' } 
    AND default_time_to_live = 0 
    AND speculative_retry = '99PERCENTILE' 
    AND min_index_interval = 128 
    AND max_index_interval = 2048 
    AND crc_check_chance = 1.0; 

：

cqlsh> use mykeyspace; 
cqlsh:mykeyspace> select * from temperature where weatherstation_id='1234ABCD' 
       ... ; 

weatherstation_id | event_time    | temperature 
-------------------+--------------------------+------------- 
      1234ABCD | 2013-04-03 06:01:00+0000 |   72F 
      1234ABCD | 2013-04-03 06:02:00+0000 |   73F 
      1234ABCD | 2013-04-03 06:03:00+0000 |   73F 
      1234ABCD | 2013-04-03 06:04:00+0000 |   74F 
      1234ABCD | 2013-04-03 06:05:00+0000 |   72F 
      1234ABCD | 2013-04-03 07:01:00+0000 |   72F 

然而，过滤不工作，还是回到了全套当我运行以下CQL：

select * from temperature where weatherstation_id='1234ABCD' and event_time > '2013-04-03 06:05:00'; 

我是否了解病情错了吗？

Answer 1

不，你理解正确的条件。但是，在使用时间戳时，Cassandra会假设您正在使用本地GMT偏移量。当我运行最后一个查询时，我根本没有得到任何行。但是当我指定GMT偏移量为+0000时，我得到一行。

aploetz@cqlsh:stackoverflow> SELECT * FROM temperature 
    WHERE weatherstation_id='1234ABCD' AND event_time > '2013-04-03 06:05:00+0000'; 

weatherstation_id | event_time    | temperature 
-------------------+--------------------------+------------- 
      1234ABCD | 2013-04-03 07:01:00+0000 |   72F 

(1 rows) 

改变你eventime >部分以包含GMT的偏移+0000我有，你应该看到预期的结果。