How can I change the sample size to speed up report loading?


Available from 16.33.0

In Piwik PRO, you can change the sample size for your reports to customize their accuracy and speed. A smaller sample size will generate reports faster, while a larger sample size may take more time to process but will bring more accurate results. The default sample size is 100%, which means that Piwik PRO uses all collected data to calculate your report.

Before you start

Here are some things to know before you change the sample size:

  • Sampling lets you use a subset of sessions to calculate metrics for all sessions. For example, if you use a sample size of 50% from 10 000 sessions, you’ll still see 10 000 sessions in your reports.
  • For small data sets, use a sample size of 100% for the most accurate results. Anything smaller can lead to inaccurate results.
  • If your reports take a long time to load or you have trouble with “memory limit” or “timeout” errors, try using a sample size below 50%. This will help your reports load much faster.
  • Once you set a sample size, it will stay that way until you change it. So if you change the date range and your data set becomes smaller, the results of your report may not be as accurate.

Change the sample size for a report

To change the sample size for a report, follow these steps:

  1. Go to Menu > Analytics.
  2. Navigate to Dashboards, Reports, Custom reports, Goals, Ecommerce or SharePoint.
  3. Click on the sampling icon at the top of the tab. The default value is 100%.
    Sampling in Piwik PRO
  4. Pick the sample size that you want. Example: 50%.
    Sampling in Piwik PRO
  5. Done! All your reports will use that sample size from now on.

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