[Cassandra] static column

最新推荐文章于 2024-09-17 19:55:46 发布

转载最新推荐文章于 2024-09-17 19:55:46 发布 · 194 阅读

0 ·

CC 4.0 BY-SA版权

原文链接：https://stackoverflow.com/questions/28767452/cassandra-static-column-design

database 专栏收录该内容

17 篇文章

订阅专栏

本文详细解析了Cassandra中如何存储带有静态列的表结构，通过实例展示了在磁盘上的存储形式，并讨论了其设计实施。重点介绍了静态列在分区中的特殊存储位置和命名规则，以及为何与其他列不同。

How are static columns stored internally in cassandra? Can someone please post an example discussing the design implementation of static column in cassandra?

Why don't we take a look at the structure of a table with static columns on disk and find out?

cqlsh:test> CREATE TABLE test (k int, v int, s int static, d int, PRIMARY KEY(k,v))

cqlsh:test> INSERT INTO test (k, v, s, d) VALUES ( 1, 1 ,20, 1 );
cqlsh:test> INSERT INTO test (k, v, s, d) VALUES ( 1, 3 ,21, 2 );
cqlsh:test> INSERT INTO test (k, v, s, d) VALUES ( 1, 2 ,21, 2 );

Exit out of cqlsh and run nodetool flush to make our sstables. Run sstable2json on the .db file that was created in the data directory.

[
{"key": "1", <--- K=1 Partition
 "cells": [[":s","21",1425050917842350], <---- Our Static Column
           ["1:","",1425050906896717], < --- v=1 row
           ["1:d","1",1425050906896717], < --- v=1, d=1 value
           ["2:","",1425050917842350], < --- v=2 row
           ["2:d","2",1425050917842350], < --- v=2, d=2 value
           ["3:","",1425050912874025], <--- v=3 Row
           ["3:d","2",1425050912874025]]} <--- v=3, d=2 Value
]

You can see that in Cassandra this static column is held in a cell with the title "Blank:ColumnName" at the very beginning of our partition. Unlike all the other cells there is no information about c(our clustering column) in the cell name, so all values of c will still modify the same static column s

Reference:

https://stackoverflow.com/questions/28767452/cassandra-static-column-design

http://www.datastax.com/dev/blog/cql-in-2-0-6