将cassandra查询结果导出到csv文件 [英] Export cassandra query result to a csv file

问题描述

我是cassandra的新用户，我必须将特定查询的结果导出到csv文件。

I'm new in cassandra, and I have to export the result of a specific query to a csv file.

我发现 COPY 命令，但是（从我的理解）它允许你只将现有的表复制到csv文件，我想要的是直接复制我的查询的stdout到csv文件。有没有办法用 COPY 命令或用另一种方式？

I found the COPY command, but (from what I understand) it allows you only to copy an already existing table to a csv file, and what I want is to copy directly the stdout of my query to the csv file. is there any way to do it with COPY command or with another way ?

我的命令是style c $ c> select column1，column2 from table where condition = xy ）和我使用 cqlsh 。

My command is style (select column1, column2 from table where condition = xy) and I'm using cqlsh.

推荐答案

如果你不介意你的数据使用管道（'|'）作为分隔符，你可以尝试使用 -e 在cqlsh上的标志。 -e 标志允许您从命令提示符处向Cassandra发送查询，您可以在此输出重定向甚至执行grep / awk /任何操作。

If you don't mind your data using a pipe ('|') as a delimiter, you can try using the -e flag on cqlsh. The -e flag allows you to send a query to Cassandra from the command prompt, where you could redirect or even perform a grep/awk/whatever on your output.

$ bin/cqlsh -e'SELECT video_id,title FROM stackoverflow.videos' > output.txt
$ cat output.txt

 video_id                             | title
--------------------------------------+---------------------------
 2977b806-df76-4dd7-a57e-11d361e72ce1 |                 Star Wars
 ab696e1f-78c0-45e6-893f-430e88db7f46 | The Witches of Whitewater
 15e6bc0d-6195-4d8b-ad25-771966c780c8 |              Pulp Fiction

(3 rows)

旧版本的cqlsh具有 -e 标志。对于旧版本的cqlsh，您可以将命令放入一个文件，并使用 -f 标志。

Older versions of cqlsh don't have the -e flag. For older versions of cqlsh, you can put your command into a file, and use the -f flag.

$ echo "SELECT video_id,title FROM stackoverflow.videos;" > select.cql
$ bin/cqlsh -f select.cql > output.txt

从这里开始执行 cat on output.txt应该产生与上面相同的行。

From here, doing a cat on output.txt should yield the same rows as above.

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