cassandra - cassandra中二级索引的范围查询

Question

我使用的是 cassandra 2.1.10。所以首先我要明确一点，我知道二级索引是 cassandra 中的反模式。但出于测试目的，我尝试执行以下操作:

CREATE TABLE test_topology1.tt (
    a text PRIMARY KEY,
    b timestamp
) WITH 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'}
    AND compression = {'sstable_compression': 'org.apache.cassandra.io.compress.LZ4Compressor'}
    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 = '99.0PERCENTILE';
CREATE INDEX idx_tt ON test_topology1.tt (b);

当我运行以下查询时，它给出了错误。

cqlsh:test_topology1> Select * from tt where b>='2016-04-29 18:00:00' ALLOW FILTERING;
InvalidRequest: code=2200 [Invalid query] message="No secondary indexes on the restricted columns support the provided operators: 'b >= <value>'"

而这个Blog说允许过滤可以用来查询二级索引。Cassandra 安装在 Windows 计算机上。

Answer 1

Cassandra 2.2.x 及之前版本不允许对二级索引列进行范围查询。然而，正如帖子 A deep look at the CQL WHERE clause 指出，如果允许过滤，则允许在非索引列上使用它们:

Direct queries on secondary indices support only =, CONTAINS orCONTAINS KEY restrictions.

[..]

Secondary index queries allow you to restrict the returned resultsusing the =, >, >=, <= and <, CONTAINS and CONTAINS KEY restrictionson non-indexed columns using filtering.

因此，给定表结构和索引

CREATE TABLE test_secondary_index (
     a text PRIMARY KEY,
     b timestamp,
     c timestamp 
);
CREATE INDEX idx_inequality_test ON test_secondary_index (b);

以下查询失败，因为不等式测试是在索引列上完成的:

SELECT * FROM  test_secondary_index WHERE b >= '2016-04-29 18:00:00' ALLOW FILTERING ;
InvalidRequest: code=2200 [Invalid query] message="No secondary indexes on the restricted columns support the provided operators: 'b >= <value>'"

但是以下方法有效，因为不等式测试是在非索引列上完成的:

SELECT * FROM  test_secondary_index WHERE b = '2016-04-29 18:00:00' AND c >= '2016-04-29 18:00:00' ALLOW FILTERING ;

 a | b | c
---+---+---

(0 rows)

如果您在列 c 上添加另一个索引，这仍然有效，但仍然需要 ALLOW FILTERING 术语，这对我来说意味着列 c 上的索引不是在这个场景中使用。