列数大于 1996099046，无法计算百分位数

Question

当我运行 Table直方图收到以下消息时：

NodeTool Table直方图键空间 Table名称

Column counts are larger than 1996099046, unable to calculate percentiles

Percentile  SSTables     Write Latency      Read Latency    Partition Size        Cell Count
                              (micros)          (micros)           (bytes)
50%             0.00              0.00              0.00         268650950               NaN
75%             0.00              0.00              0.00        3449259151               NaN
95%             0.00              0.00              0.00       25628284214               NaN
98%             0.00              0.00              0.00       44285675122               NaN
99%             0.00              0.00              0.00       44285675122               NaN
Min             0.00              0.00              0.00            105779                 0
Max             0.00              0.00              0.00       442856751229223372036854776000

Cassandra 版本：

[cqlsh 5.0.1 | Cassandra 3.11.2 | CQL spec 3.4.4 | Native protocol v4]
Use HELP for help.

Replication factor 3
4 node cluster
Getting the above message in one node only 
Tried repairing the table but failed with streaming error :

40328:ERROR [StreamReceiveTask:53] 2019-06-10 13:54:33,684 StreamSession.java:593 - [Stream #c9214180-8b82-11e9-90ce-399bac480141] Streaming error occurred on session with peer <IP ADDRESS>
40329-java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.IllegalStateException: Unable to compute ceiling for max when histogram overflowed
40330-  at org.apache.cassandra.utils.Throwables.maybeFail(Throwables.java:51) ~[apache-cassandra-3.11.2.jar:3.11.2]
40331-  at org.apache.cassandra.utils.FBUtilities.waitOnFutures(FBUtilities.java:373) ~[apache-cassandra-3.11.2.jar:3.11.2]
40332-  at org.apache.cassandra.index.SecondaryIndexManager.buildIndexesBlocking(SecondaryIndexManager.java:383) ~[apache-cassandra-3.11.2.jar:3.11.2]
40333-  at org.apache.cassandra.index.SecondaryIndexManager.buildAllIndexesBlocking(SecondaryIndexManager.java:270) ~[apache-cassandra-3.11.2.jar:3.11.2]
40334-  at org.apache.cassandra.streaming.StreamReceiveTask$OnCompletionRunnable.run(StreamReceiveTask.java:216) ~[apache-cassandra-3.11.2.jar:3.11.2]
40335-  at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [na:1.8.0_144]
40336-  at java.util.concurrent.FutureTask.run(FutureTask.java:266) [na:1.8.0_144]
40337-  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_144]
40338-  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_144]
--
0354:ERROR [Reference-Reaper:1] 2019-06-10 13:54:33,907 Ref.java:224 - LEAK DETECTED: a reference (org.apache.cassandra.utils.concurrent.Ref$State@7bd8303d) to class org.apache.cassandra.io.util.ChannelProxy$Cleanup@1084465868:PATH/talename-5b621cd0c53311e7a612ffada4e45177/mc-26405-big-Index.db was not released before the reference was garbage collected

Table 描述包括：

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 crc_check_chance = 1.0
    AND dclocal_read_repair_chance = 0.1
    AND default_time_to_live = 0
    AND gc_grace_seconds = 864000
    AND max_index_interval = 2048
    AND memtable_flush_period_in_ms = 0
    AND min_index_interval = 128
    AND read_repair_chance = 0.0
    AND speculative_retry = '99PERCENTILE';

知道为什么会这样吗？欢迎任何帮助或建议。

Answer 1

一个分区中不能有 20 亿个单元格。此外，由于多种原因，在具有 44gb 分区的 table 上设置二级索引也会出现问题。除了删除索引并构建要迁移到的新数据模型之外，您确实无能为力。您可以构建一个自定义版本的 Cassandra 来忽略该异常，但是当您处于理论上可能的极限时，很快就会出现其他问题。你已经超过了让我感到惊讶的一点运行。

如果流错误是由于修复引起的，您可以在修复数据模型时忽略它。如果它来自引导程序，我认为您将需要一个自定义版本的 Cassandra 以同时保持运行（或者可以忽略您要替换的故障节点）。请记住，节点故障现在对您来说是一个严重的威胁，因为引导程序可能无法正常工作。当您在单个分区中放置这么多内容时，它无法横向扩展，因此选项有限。

列数大于 1996099046，无法计算百分位数

Column counts are larger than 1996099046, unable to calculate percentiles

cassandra

cassandra-3.0