Question

在Oracle中，有可能add a comment关于数据字典中的表，视图，物化视图或列，例如。

COMMENT ON COLUMN employees.job_id 
   IS 'abbreviated job title';

当我试图理解不一定可自行解释的名称背后的想法以及大型数据库（超过200个表）时，我发现这对测试人员特别有用。

Cassandra有这样的功能吗？

Answer 1

您可以使用'with comment'选项

cqlsh:d2> 
cqlsh:d2> create table employee (id int primary key, name text) with comment = 'Employee id and name';
cqlsh:d2> desc table employee;

CREATE TABLE d2.employee (
    id int PRIMARY KEY,
    name text
) WITH bloom_filter_fp_chance = 0.01
    AND caching = '{"keys":"ALL", "rows_per_partition":"NONE"}'
    AND comment = 'Employee id and name'
    AND compaction = {'min_threshold': '4', 'class': 'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy', 'max_threshold': '32'}
    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';

Cassandra documentation

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