I've googled some tutorials, browsed some SO answers, and was unable to find a recipe for my problem.
I'm writing a web site which is supposed to display almost realtime stock chart. Data is stored in constantly updating MySQL database, I wrote a find_by_sql query code which fetches all the data I need to get my chart drawn. Everything is ok, except performance - it takes from one second to one minute for different queries to fetch all the data from the database, this time includes necessary (My)SQL-server side calculations. This is simply unacceptable.
I got the following idea: if the data is queried from the MySQL server one point a time instead of entire dataset, it takes only about 1-100ms to get an individual point.
I imagine the data fetch process might be browser-driven. After the user presses the button in order to get a chart drawn, controller makes one request to the database and renders, say, a progress bar, say 1% ready. When the browser gets the response, it immediately makes an (ajax) request, and the server fetches the next piece of data and renders "2%".
And so on, until all the data is ready and the server displays the requested chart. Could this be implemented in rails+js, is there a tutorial for solving a similar problem on the Web? I suppose if the thing is feasible at all, somebody should have already done this before.
I have read several articles about ajax, I believe I do understand general principles, but never did nontrivial ajax programming m开发者_高级运维yself.
Thanks for your time!
You could load the page with a div that displays an animated gif (indicating "working"). Then, use body onload to launch your ajax request and replace the contents of that div.
<body onload="some function call to Ajax.Updater('chart')">
<div id="chart">
<img src="working.gif">
</div>
![Interactive visualization of a graph in python [closed]](https://www.devze.com/res/2023/04-10/09/92d32fe8c0d22fb96bd6f6e8b7d1f457.gif)
加载中,请稍侯......
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