cassandra中二级索引的范围查询

Question

我正在使用 cassandra 2.1.10。所以首先我要明确我知道二级索引在 cassandra.But 中是反模式的，出于测试目的我正在尝试以下操作：

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);

当我运行查询后出现错误。

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>'"

虽然这个Blog说允许过滤可以用来查询二级索引。 Cassandra 安装在 windows 机器上。

Answer 1

这会让您得到想要的结果。使用 b 作为聚类列。

创建 TABLE test_topology1.tt ( 一段文字， b 时间戳，主键 (a, b) )

select * from tt where b>='2016-04-29 18:00:00' 允许过滤；

Answer 2

范围查询确实使用ALLOW FILTERING

与二级索引一起工作

cqlsh:spark_demo> create table tt (
              ...     a text PRIMARY KEY,
              ...     b timestamp
              ... );
cqlsh:spark_demo> CREATE INDEX ON tt(b);
cqlsh:spark_demo> SELECT * FROM tt WHERE b >= '2016-03-01 12:00:00+0000';
InvalidRequest: code=2200 [Invalid query] message="No supported secondary index found for the non primary key columns restrictions"
cqlsh:spark_demo> SELECT * FROM tt WHERE b >= '2016-03-01 12:00:00+0000' ALLOW FILTERING;

 a | b
---+---

(0 rows)
cqlsh:spark_demo>

Answer 3

在 2.2.x 之前的 Cassandra 中，不允许对二级索引列进行范围查询。但是，正如 post A deep look at the CQL WHERE clause 指出的那样，如果全部过滤，则允许在非索引列上使用它们：

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

[..]

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

因此，给定 table 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>'"

但以下内容有效，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 c 列上添加另一个索引，这仍然有效，但仍然需要 ALLOW FILTERING 项，这对我来说意味着在这种情况下不使用 c 列上的索引。

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