cassandra - Cassandra 的“system.size_estimates”没有显示大小

Question

我在 Cassandra 中有一个表，其中包含超过 20 亿条记录（最大 int 值），但分区不充分。认为：

> create table if not exists bar (
 bar_id bigint,
 col_a text,
 col_b text,
 col_c int,
 col_d text,
 primary key (bar_id, col_a, col_b, col_c))

我已经刷新了大小估计，nodetool refreshsizeestimates我可以看到数据很好，但所有行都在同一个标​​记下：

> select col_a, col_b, col_c from foo.bar where bar_id = 1;

 col_a  | col_b |  col_c
--------+-------+--------
 aaaaaa | b     |      0
 aaaaaa | bb    |      1
 aaaaaa | bb    |      2
 aaaaaa | bbb   |      1

> select col_a, col_b, col_c
 from foo.bar
 where bar_id = 1
 and token(crawl_id) < 6121040252107678107 
 and token(crawl_id) > 6121040252107678107;

 col_a  | col_b |  col_c
--------+-------+--------

(0 rows)

然而，分区大小显示为零：

> select * from system.size_estimates 
 where keyspace_name = 'foo' and table_name = 'bar';


 keyspace_name | table_name  | range_start         | range_end           | mean_partition_size | partitions_count
---------------+-------------+---------------------+---------------------+---------------------+------------------
 foo           | bar         | 6038186684182191258 | 6054588198651336225 |                   0 |                0
 foo           | bar         | 6892562529594743760 | 6908565156302797782 |                   0 |                0
 foo           | bar         | 6944218160728667924 | 6944876930711291150 |                   0 |                0
 ...

密钥空间复制设置为 1。

> create keyspace foo 
 with replication = {'class': 'NetworkTopologyStrategy', 'south': '1'} and durable_writes = true;

如何获得整个或每个分区的正确大小或有关令牌/数据的任何信息？

---

$ nodetool tablehistograms -- foo bar
foo/bar histograms
Percentile  SSTables     Write Latency      Read Latency    Partition Size        Cell Count
                              (micros)          (micros)           (bytes)
50%            20.00              0.00         155469.30        8582860529         129557750
75%            20.00              0.00         186563.16      158683580810         268650950
95%            20.00              0.00         186563.16      568591960032        1996099046
98%            20.00              0.00         186563.16      568591960032        1996099046
99%            20.00              0.00         186563.16      568591960032        1996099046
Min            18.00              0.00         129557.75         268650951                 0
Max            20.00              0.00         186563.16      568591960032        1996099046

---

卡桑德拉版本3.11.2。

标签： cassandrapartitioningcql