我有存储在客户端浏览器内存中的数据。例如，假设数据集如下:

"name" (string),     "age" (int32),   "isAdult" (bool)
"Tom"          ,     29               1
"Tom"          ,     14               0
"Dina"         ,     20               1

我想在 javascript 中对此数据运行重要的 SQL 语句，例如:

SELECT name, GROUP_CONCAT(age ORDER BY age) ages
FROM arrowData a1 JOIN arrowData a2 USING (name)
WHERE a1.isAdult != a2.isAdult

我会得到:

"name" (string),      "ages" (string)
"Tom"                 "14,29"

我在 javascript 中拥有的数据存储在 apache Arrow 中(也与 Perspective 结合使用)，我也想对该 apache Arrow 数据执行 SQL。作为最后的手段，我认为可以使用 sqllite in wasm ，但我希望可能有一种更简单的方法，我可以直接查询 Arrow 数据，而不必将其全部移动到 sqllite 存储中以对其执行查询。

有没有办法做到这一点？

最佳答案

这是您正在寻找的好东西。 :) 遗憾的是，由于 ~2010 年的一些趋势，据我所知，没有为此积极维护和支持的 API。 但是……

如果你想拥有完整的ANSI SQL 在内存中的客户端，您愿意填充数据库，您可以运行提到的 SQLite .也许这是您唯一满意的选择(如果您不能留下一些要求)。

如果您允许奢侈地复制数据，您可以查看 AlaSQL project它确实支持join -s 和一些 ANSI SQL 特性，但它并不完整，它包含已知的 disruptive bugs :

Please be aware that AlaSQL has bugs. Beside having some bugs, there are a number of limitations:

AlaSQL has a (long) list of keywords that must be escaped if used for column names. When selecting a field named key please write SELECT key FROM ... instead. This is also the case for words like value, read, count, by, top, path, deleted, work and offset. Please consult the full list of keywords.

It is OK to SELECT 1000000 records or to JOIN two tables with 10000 records in each (You can use streaming functions to work with longer datasources - see test/test143.js) but be aware that the workload is multiplied so SELECTing from more than 8 tables with just 100 rows in each will show bad performance. This is one of our top priorities to make better.

Limited functionality for transactions (supports only for localStorage) - Sorry, transactions are limited, because AlaSQL switched to more complex approach for handling PRIMARY KEYs / FOREIGN KEYs. Transactions will be fully turned on again in a future version.

A (FULL) OUTER JOIN and RIGHT JOIN of more than 2 tables will not produce expected results. INNER JOIN and LEFT JOIN are OK.

Please use aliases when you want fields with the same name from different tables (SELECT a.id AS a_id, b.id AS b_id FROM ?).

At the moment AlaSQL does not work with JSZip 3.0.0 - please use version 2.x.

JOINing a sub-SELECT does not work. Please use a with structure (Example here) or fetch the sub-SELECT to a variable and pass it as an argument (Example here).

AlaSQL uses the FileSaver.js library for saving files locally from the browser. Please be aware that it does not save files in Safari 8.0.

There are probably many others. Please help us fix them by submitting an issue. Thank you!

我们计划在一个项目中使用它，但在将项目引入我们的堆栈时，问题多于解决方案(对我们而言)。所以我们退出了。所以我没有这 block 软件的生产经验……

以前我希望 Google Gears 将支持类似所需功能的功能，但部分已被 HTML5 取代客户端存储，遗憾的是项目得到了discontinued.

HTML5 WebSQL Database 对于您的用例来说是完美的，但遗憾的是 depricated 。大多数(？)浏览器在 2019 年仍然支持它。您可以查看一些示例 here .如果您可以允许自己在已弃用的 API 上进行构建，这可能是解决方案，但我真的不推荐它，因为它不能保证它会工作...

当我们的项目运行遇到同样的问题时，我们最终不得不使用 localStorage并手动对每个“SELECT”进行编程，这当然完全不像 ANSI SQL...

关于javascript - SQL 在浏览器中的 apache 箭头之上？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/56606447/