Hi,
I am trying to chart some large time/ data series from a mysql db using pchart linechart on a low power pc (guruplug). After a few teething problems I am now able to scrape together a basic chart but my main problem is once I go much over 100 data points I start to get timeout (30 sec) issues.

I am currently measuring the data every 6 seconds and would like to chart daily, weekly, monthly plots. Clearly I can do some data decimation work but I am wondring whether this will always be a 'lost cause' on such a low power pc?

Should I look for a client side (possibly javascript) charting app or do you have some advice that could help?

Thanks in advance.

Hi,

You can investigate in different directions :

1. Use the crontab to generate the charts (and use the set_time_limit() PHP function)
2. Disable AAliasing processing : http://wiki.pchart.net/doc.faq.antialiasing.html
3. Make use of the pCache library (maybe not relevant in your situation)
4. Go for a client side library (JS)

Kind regards,
JD.

JD,
Thanks for the reply. I turned off anti-aliasing and that certainly made a difference but still only allows a 'slightly' larger chart.

It appears that the timeout is coming from the class so would the set_time_limit() make a difference?



I would hate to have to go down the js path after getting into pChart.

Thanks again.

Yes it will! But the issue I see is that a web user will not wait 40s for an image to be displayed. For such kind of project, I prefer to go for an MRTG like solution where the collecting daemon also create the static image file so no rendering is done anymore for the web side. (This is what I've done here : http://wiki.pchart.net/doc.real.world.html)

JD.

Hum, just checked the line and it belongs to the drawScale() function which is quiet strange.

Can you please show me your code? I believe that it's a bug I've not experienced yet.

Thanks!
JD.

PM sent with code.

This thread's a bit old, but I doubt the problem is in pChart.

100 data-points is minuscule on today's machines.

As a point-of-reference, I can easily pull 100 OHLC data points into pChart's StockChart from a $300 32-bit Ubuntu machine I bought 3 years ago, running MySQL.
The png is drawn by pchart within a second.

If you are timing out with 30 seconds, you need to break it down - see how long the query takes in command-line mysql first: if that takes a while,
I suspect you are missing an index on a table. If it is fast, there's probably a bug in how you are using pChart.