[英]Cassandra column family for Composite Columns?
I am designing the Column Family for our use case in Cassandra. 我正在为Cassandra中的用例设计Column Family。 I am planning to go with Dynamic Column Structure. 我打算使用动态列结构。
Below is my requirement per our use case- 以下是根据我们的用例我的要求-
user-id column1 column2 column3
123 (Column1-Value Column1-SchemaName LMD) (Column2-Value Column2-SchemaName LMD) (Column3-Value Column3-SchemaName LMD)
For each user-id, we will be storing column1 and its value and that value will store these three things always- 对于每个用户ID,我们将存储column1及其值,并且该值将始终存储这三件事-
(Column1-Value Column1-SchemaName LMD)
In my above example, I have show only three columns but it might have more columns. 在上面的示例中,我只显示了三列,但可能有更多列。
Now I am not sure, how to store these three thing always at a column value level? 现在我不确定,如何始终将这三件事存储在列值级别? Should I use composite columns at a column level? 我应该在列级别使用复合列吗? if yes, then I am not sure how to make a column family like this in Cassandra. 如果是,那么我不确定如何在Cassandra中创建这样的列族。
Column1-value will be in binary, Column1-SchemaName will be String, LMD will be DateType.
This is what I have so far- 这就是我到目前为止
create column family USER_DATA
with key_validation_class = 'UTF8Type'
and comparator = 'UTF8Type'
and default_validation_class = 'UTF8Type'
and gc_grace = 86400
and column_metadata = [ {column_name : 'lmd', validation_class : DateType}];
Can anyone help me in designing the column family for this? 有人可以帮助我为此设计色谱柱系列吗?
@TechGeeky @TechGeeky
Change the comparator to : 将比较器更改为:
comparator = 'CompositeType(ByteType,UTF8Type,DateType)'
ByteType for Column-Value 列值的ByteType
UTF8Type for Column-SChemaName 列SChemaName的UTF8Type
DateType for LMD LMD的DateType
Be careful though, with this design, querying your data other than by user-id would be hard. 但是请注意,使用这种设计,很难查询用户ID以外的数据。 Especially you would be able to get slices of columns by providing column data (in bytes), if you know them before hand... 特别是,如果您事先知道列数据,则可以通过提供列数据(以字节为单位)来获取列切片...
I would suggest you use CQL3. 我建议您使用CQL3。 If you use Cassandra 1.2+ and CQL3, the following table will result in the partition (row) layout you describe. 如果使用Cassandra 1.2+和CQL3,则下表将导致您描述的分区(行)布局。
CREATE TABLE user_data (
userid text,
data bytes,
schema_name string,
lmd timestamp,
PRIMARY KEY (userid, data, schema_name, lmd)
)
You can see the following article for more information on how CQL3 ends up as composite columns under the hood, and makes them much easier to use: 您可以查看以下文章,详细了解CQL3如何最终成为引擎盖下的复合柱,并使它们更易于使用:
http://www.datastax.com/dev/blog/cql3-for-cassandra-experts http://www.datastax.com/dev/blog/cql3-for-cassandra-experts
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