讲故事的变量与次级指数是否会降低卡桑德拉的性能？

发布于 2025-02-06 10:40:30 字数 826 浏览 2 评论 0原文

我想建立一个系统，以报告在具有反变量的活动期间参加课程的人数。主要键是事件ID，辅助键将是舞台的名称。以科技公司的领域为例。

CREATE TABLE event (
    event_id text,
    stand text,
    nb counter,
    PRIMARY KEY(event_id, stand)
)

INSERT INTO event(event_id, stand, nb) VALUES (2, "appel", 0);
INSERT INTO event(event_id, stand, nb) VALUES (2, "google", 0);
INSERT INTO event(event_id, stand, nb) VALUES (2, "amazon", 0);

我的问题是，在Cassandra文档中，建议将尽可能少的索引放在柜台表上。最好的是创建一个带有两个索引的单个表或为每种类型的Stand创建一个表（这将不需要更多命令来恢复信息）

CREATE TABLE stand_name (
    event_id text,
    nb counter,
    PRIMARY KEY (event_id)
)

INSERT INTO google(event_id, nb) VALUES (2, "appel", 0);
INSERT INTO amazon(event_id, nb) VALUES (2, "google", 0);
INSERT INTO apple(event_id, nb) VALUES (2, "amazon", 0);

原文

I would like to make a system to report the number of people who went to a course during an event with a counter variable. The primary key would be the event id and the secondary key would be the name of the stage.
Take, for example, an area where there are tech companies.

CREATE TABLE event (
    event_id text,
    stand text,
    nb counter,
    PRIMARY KEY(event_id, stand)
)

INSERT INTO event(event_id, stand, nb) VALUES (2, "appel", 0);
INSERT INTO event(event_id, stand, nb) VALUES (2, "google", 0);
INSERT INTO event(event_id, stand, nb) VALUES (2, "amazon", 0);

My problem is that in the cassandra documentation it is advised to put as few indexes as possible on the counter tables. The best is to create a single table with two indexes or to create a table for each type of stande (which will not require more command to recover the information)

CREATE TABLE stand_name (
    event_id text,
    nb counter,
    PRIMARY KEY (event_id)
)

INSERT INTO google(event_id, nb) VALUES (2, "appel", 0);
INSERT INTO amazon(event_id, nb) VALUES (2, "google", 0);
INSERT INTO apple(event_id, nb) VALUES (2, "amazon", 0);

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帥小哥 2025-02-13 10:40:30

我必须承认，我对您的问题感到困惑，并且不太了解索引如何发挥作用。

使用柜台表，您只能拥有：

构成主键的列，而
计数列本身

要检索计数器值，您必须提供主键：

SELECT counter_col FROM counter_tbl WHERE pk = ?

在表上创建辅助索引没有任何好处，因为确实存在ISN任何要索引的东西 - 除计数器本身以外，没有其他列存储在柜台表中。干杯!

I have to admit that I'm confused by your question and don't quite understand how indexing comes into play.

With counter tables, you can only have:

the columns which form the primary key, and
the counter column itself

To retrieve the counter value, you must provide the primary key:

SELECT counter_col FROM counter_tbl WHERE pk = ?

There is no benefit in creating secondary indexes on the table because there really isn't anything to index -- there are no other columns stored in a counter table other than the counter itself. Cheers!

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