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 的新手，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.

我找到了 COPY 命令，但是(据我所知)它只允许您将已经存在的表复制到 csv 文件，而我想要的是直接复制我的标准输出查询 csv 文件.有没有办法用 COPY 命令或其他方法来做到这一点?

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 ?

我的命令是样式(select column1, column2 from table where condition = xy)，我使用的是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 cqlsh 上的标志.-e 标志允许您从命令提示符向 Cassandra 发送查询，您可以在其中重定向甚至在输出上执行 grep/awk/whatever.

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 没有 -e 标志.对于旧版本的 cqlsh，您可以将命令放入文件中，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，对 output.txt 执行 cat 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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